Enzymatic activity of bone markers on Lithobates catesbeianus (Shaw, 1802) growth during the ossification process / Atividade enzimática de marcadores ósseos no crescimento de Lithobates catesbeianus (Shaw, 1802) durante o processo de ossificação

Abstract In order to better understand the ossification processes in anurans our study was carried out on tadpoles and adults of Lithobates catesbeianus. In this sense, we characterized the kinetic properties of alkaline phosphatase with p-nitrophenylphosphatase (pNPP) and pyrophosphate (PPi) and evaluated the activities of tartrate-resistant acid phosphatase and acid phosphatase. The enzyme extracts were obtained from tadpoles and adult femurs, which were divided into epiphysis and diaphysis. After homogenization, the samples were submitted to differential centrifugation to obtain cell membranes and, further, to phospholipase C (PIPLC) treatment, to remove membrane-bound proteins anchored by phosphatidylinositol. The average of specific activity for pNPP hydrolysis (at pH 10.5) by alkaline phosphatase released by phosphatidylinositol-specific phospholipase C (PIPLC) from Bacillus cereus among different bone regions at different animal ages was 1,142.57 U.mg-1, while for PPi hydrolysis (at pH 8.0), it was 1,433.82 U.mg-1. Among the compounds tested for enzymatic activity, the one that influenced the most was EDTA, with approximately 67% of inhibition for pNPPase activity and 77% for PPase activity. In the case of kinetic parameters, the enzyme showed a "Michaelian" behavior for pNPP and PPi hydrolysis. The Km value was around 0.6mM for pNPPase activity and ranged from 0.01 to 0.11mM for PPase activity, indicating that the enzyme has a higher affinity for this substrate. The study of pNPP and PPi hydrolysis by the enzyme revealed that the optimum pH of actuation for pNPP was 10.5, while for PPi, which is considered the true substrate of alkaline phosphatase, was 8.0, close to the physiological value. The results show that regardless of the ossification type that occurs, the same enzyme or isoenzymes act on the different bone regions and different life stages of anurans. The similarity of the results of studies with other vertebrates shows that anurans can be considered excellent animal models for the study of biological calcification.

Resumo Para melhor compreender o processo de ossificação em anuros, nosso estudo foi conduzido em girinos e adultos de Lithobates catesbeianus. Nesse sentido, as propriedades cinéticas da fosfatase alcalina com p-nitrofenilfosfato (pNPP) e pirofosfato (PPi) foram caracterizadas, e as atividades enzimáticas das fosfatases ácida e ácida tartarato resistente foram avaliadas. Os extratos enzimáticos foram obtidos de fêmur de girinos e adultos, divididos em epífise e diáfise. Após a homogeneização as amostras foram submetidas à centrifugação diferencial para obter membrana celular e, em seguida, ao tratamento com fosfolipase C (PIPLC), para remover as proteínas de membrana ancoradas por fosfatidilinositol. A média da atividade específica da fosfatase alcalina, liberada pela PIPLC de Bacillus cereus, para a hidrólise de pNPP (pH 10,5) nas diferentes regiões do fêmur e idades dos animais foi de 1.142,57 U.mg-1, enquanto para a hidrólise do PPi (pH 8,0) foi de 1.433,82 U.mg-1. Entre os compostos testados para a atividade enzimática, o de maior influência foi o EDTA, inibindo aproximadamente 67% e 77% das atividades de pNPPase e PPase, respectivamente. Quanto aos parâmetros cinéticos, a enzima apresentou comportamento Michaeliano para a hidrólise dos dois substratos. O valor de Km foi de 0,6 mM para a atividade de pNPPase e variou de 0,01 a 0,11 para a atividade de PPase, indicando uma maior afinidade por esse substrato. O estudo da hidrólise de pNPP e PPi revelou que o pH ótimo aparente de atuação foi de 10,5 para o pNPP e 8,0 para o PPi, próximo ao fisiológico, sendo que esse é considerado o substrato natural da fosfatase alcalina. Os resultados demonstram que, apesar do tipo de ossificação que ocorre, a mesma enzima ou isoenzimas, atuam nos diferentes locais do osso e estágios de vida dos anuros. A similaridade dos estudos com os realizados com outros vertebrados apontam que os anuros podem ser considerados excelentes modelos animais para o estudo da calcificação biológica.

The Influence of Morphological Characteristics on the Ball Throwing Velocity in the Professional Handball Players / Influencia de las Características Morfológicas en la Velocidad de Lanzamiento del Balón en los Jugadores Profesionales de Balonmano

SUMMARY: The aim of this study was to determine influence of upper limbs on the ball throwing velocity. A total of 10 professional handball players (25.74±4.84 years) participated in this study. All of them were playing in the top Montenegrin professional handball league. The results obtained in this study shows that upper limbs have high influence on ball throwing velocity. This study provides normative data and performance standards for professional handball. Coaches can use this information to determine the type of anthropometric characteristics that are needed for handball. Anthropometric parameters such as arm length, wrist diameter, hand length and arm span are the most relevant aspects related to ball throwing speed, given that these parameters cannot be changed through training, they should be taken into account when discovering talents.

El objetivo de este estudio fue determinar la influencia de los miembros superiores sobre la velocidad de lanzamiento de la pelota. En el estudio participaron un total de 10 jugadores profesionales de balonmano (25,74±4,84 años). Todos ellos jugaban en la principal liga profesional de balonmano de Montenegro. Los resultados obtenidos mostraron que los miembros superiores tienen una alta influencia en la velocidad de lanzamiento de la pelota. Este estudio proporciona datos normativos y estándares de rendimiento para el balonmano profesional. Los entrenadores pueden utilizar esta información para determinar el tipo de características antropométricas necesarias para el balonmano. Los parámetros antropométricos como la longitud del brazo, el diámetro de la muñeca, la longitud de la mano y la envergadura del brazo son los aspectos más relevantes relacionados con la velocidad de lanzamiento de la pelota, dado que estos parámetros no se pueden cambiar mediante el entrenamiento, deben tenerse en consideración a la hora de descubrir talentos.

Analysis of drying kinetic of brewer ́s spent grains: effect of the temperature on the physical properties and the content of bioactive compounds / Análisis de la cinética de secado del bagazo residual de malta: efecto de la temperatura sobre las propiedades físicas y el contenido de compuestos bioactivos

Background: Brewer ́s spent grain (BSG) is a biomass by-product generated in large volumes during industrial beer production. BSG has become a growing environmental problem, as most breweries discard it inappropriately, negatively impacting the environment. Alternatives for the exploitation of this by-product have consisted of elaborating food supplements for farm animals, obtaining biofuels, developing adsorbents, and obtaining substances for the food industry. However, the high moisture content in BSG (approximately 70%), poses a significant challenge in exploring various reuse alternatives. Therefore, the implementation of a pre-drying process becomes essential. Objective: This study aimed to analyze the BSG drying kinetics at different temperatures and the effect of the drying temperature on the physical properties and the content of bioactive compounds. Methods: BSG samples were dried at different temperatures (50, 60, 70, 80, 90, and 105°C) and analyzed for their moisture ratio, water activity, total polyphenol content (TPC), and DPPH (1,1-diphenyl-2-picrylhydrazil) radical scavenging activity. Also, four kinetics models were fitted to the drying data. Results:It was determined that the effective diffusivity was between 5.23x10

Antecedentes: El Bagazo residual de malta (BSG por sus siglas en inglés) es un subproducto biomásico generado en grandes volúmenes durante la producción industrial de cerveza. El BSG se ha convertido en un creciente problema para el medio ambiente, debido a que la mayoría de las cervecerías descartan inapropiadamente este residuo generando un impacto negativo al ambiente. Las alternativas para el aprovechamiento de este subproducto han consistido especialmente en la elaboración de suplementos alimenticios para animales de granja, obtención de biocombustibles, desarrollo de adsorbentes y obtención de productos para la industria alimentaria. Sin embargo, el alto contenido de humedad (~70%) del BSG representa un reto para el desarrollo de diferentes alternativas de reutilización, por lo que se hace necesario un proceso de secado previo. Objetivos: En este estudio se analizó la cinética de secado del BSG a diferentes temperaturas y el efecto de la temperatura de secado sobre sus propiedades físicas y contenido de compuestos bioactivos. Métodos: Las muestras de BSG fueron secadas a diferentes temperaturas (50, 60, 70, 80, 90 y 105°C) y analizadas en términos de razón de humedad, actividad acuosa, contenido de polifenoles totales (TPC) y actividad secuestradora del radical DPPH. Además, se ajustaron 4 modelos cinéticos a los datos de secado. Resultados: Se determinó que la difusividad efectiva del BSG varió entre 5.23x10

Fabrication of 1,4-alpha-D-glucan glucanohydrolase holding Gel-Scaffolds using Agar-Agar, a natural polysaccharide and Polyacrylamide, a synthetic organic polymer for continuous liquefaction of starch

1,4-alpha-D-glucan glucanohydrolase is among the most widely used commercial hydrolytic enzymes acting randomly on the glycosidic linkages of starch resulting in its saccharification and liquefaction. Its applicability in different industries can be improved by enhancing its stability and reusability. Therefore, in the present study attempts have been made to enhance the industrial applicability of 1,4-alpha-D-glucan glucanohydrolase from Bacillus subtilis KIBGE-HAR by adapting immobilization technology. The study developed mechanically stable, enzyme containing gel-frameworks using two support matrices including agar-agar, a natural polysaccharide and polyacrylamide gel, a synthetic organic polymer. These catalytic gel-scaffolds were compared with each other in terms of kinetics and stability of entrapped 1,4-α-D-glucan glucanohydrolase. In case of polyacrylamide gel, Km value for immobilized enzyme increased to 7.95 mg/mL, while immobilization in agar-agar resulted in decreased Km value i.e 0.277 mg/mL as compared to free enzyme. It was found that immobilized enzyme showed maximum activity at 70 °C in both the supports as compared to free enzyme having maximum activity at 60 °C. Immobilized 1,4-α-D-glucan glucanohydrolase exhibited no change in optimal pH 7.0 before and after entrapment in polyacrylamide gel and agar-agar. The enzyme containing gel-scaffold was found suitable for repeated batches of starch liquefaction in industrial processes. Agar-agar entrapped 1,4-α-D-glucanglucanohydrolase was capable to degrade starch up to seven repeated operational cycles whereas polyacrylamide entrapped enzyme conserved its activity up to sixth operational cycle.

Análise cinética e cinemática da saída de bloco em natação de atletas deficientes visuais / Kinetic and kinemaic analysis of block start in swimming in visually impaired athletes

Objetivos: investigar e correlacionar a cinética e cinemática da saída de bloco em natação de atletas deficientes visuais e normovisuais. Métodos: foram comparados parâmetros de desempenho entre os nadadores de ambos os sexos. A amostra contou com 16 nadadores, sendo 4 cegos, 2 baixa visão e 10 normovisuais. Análise inferencial com teste Shapiro-Wilk, estatística inferencial teste T e, para correlação entre variáveis, o teste de Pearson, com nível de significância em 5%. Correlacionamos a variável dinamométrica, nas fases de tempo de bloco, tempo em 5 metros e tempo em 16 metros. Resultados: foram percebidas diferenças significativas de (0,030, 0,029 e 0,001), respetivamente, pois foram menores para os nadadores normovisuais. Na variável cinética, o pico de força resultante dos nadadores normovisuais foi, significativamente, maior (0,024). O ângulo de saída dos nadadores normovisuais foi também, significativamente, maior (0,030). Nas fases de tempo de reação, tempo de voo, força horizontal e vertical, ângulo de entrada e distância de voo, não apresentaram diferenças significativas. Observou-se uma correlação expressiva, entre as variáveis tempo de bloco e tempo em 5 metros (0,688); tempo de bloco e tempo em 16 metros (0,689); tempo em 5 metros e tempo em 16 metros (0,928); e o tempo de voo e ângulo de saída (0,941). O pico de força apresentou uma correlação significativa na maioria das variáveis do estudo com exceção do tempo de reação e o ângulo entrada. Conclusão: a ausência da visão acarreta na defasagem da performance e nos resultados em provas de natação de alto rendimento para deficientes visuais.

Objectives: to investigate and correlate the kinetics and kinematics of the starting block in swimming of visually impaired and visually impaired athletes. Methods: The method used was to compare performance parameters between swimmers of both sexes. The sample had 16 swimmers being 4 blind, 2 low vision and, 10 normovisuals. Inferential analysis with Shapiro-Wilk test, inferential statistics T-test, and for correlation between variables the Pearson's test, with a significance level of 5%. We correlated the dynamometric variable, in the phases of block time, time in 5 meters and time in 16 meters. Results: Resulting in significant differences of (0.030, 0.029, and 0.001, block time, 5 and 16 meters respectively) lower for the normovisual swimmers. In the kinetic variable, the peak force resulting from normal-vision swimmers was significantly higher (0.024). The departure angle of normal-vision swimmers was also significantly higher (0.030). In the phases of reaction time, flight time, horizontal and vertical force, entry angle and flight distance, there were no significant differences. An expressive correlation was observed between the variables block time and time in 5 meters (0.688); block time and time on 16 meters (0.689); time on 5 meters and time on 16 meters (0.928); and flight time and departure angle (0.941). The force peak showed a significant correlation in most of the variables under study except for the reaction time and the imput angle. Conclusion: the absence of vision leads to a lack of performance and results in high-performance swimming tests.

Thin-layer drying characteristics, modeling and quality attributes of tomato slices dried with infrared radiation heating

An Infrared dryer was used to examine the drying of tomato slices. In this investigation, the influence of infrared radiation (IR) on the rate of drying, physical quality, energy combustion of tomato was estimated at three different levels of intensity at 0.15, 0.20, and 0.35 W/cm² under different air flows of 0.5, 1, and 1.5 m/s. Tomato slices were dried with an initial moisture content of 19.7 to 0.17 g water/g dry solids by infrared drying. The moisture content and drying rates are found to be dramatically affected by infrared density. An increase in the drying rate and a decrease in the drying period occurred with increasing infrared intensity. A decrease in energy consumption was detected with the increase of radiation intensity. The results clarified that the shrinkage ratio increased with increasing infrared intensity. The rehydration ratio raised with the increase in radiation intensity. The change in the colour difference of dried slices increased with an increase in radiation intensity. The models were in comparison using (R²) coefficient of determination, modelling efficiency (EF), and (χ²) reduced chi-square. Midilli model was fit for simulation of all drying conditions and could be used to estimate tomato moisture content at any time during the infrared drying process.

Blood glucose kinetics during concentric and eccentric muscle contractions

Studies comparing the two classes of stimuli (concentric and eccentric) have shown differences in the improvement of cardiovascular, metabolic, and muscle strength gain. This is an experimental, quantitative, and prospective study that aimed to verify the effect of eccentric exercise on glycolytic consumption and kinetics. The blood glucose kinetics of 17 male subjects was evaluated during a treadmill exercise with a 10% declined floor and velocity that required a 60% metabolic activity of VO2max, for 30 minutes. Seventy-two hours later, the same subjects exercised on the treadmill with a 10% inclined floor and 60% VO2max, for 30 minutes. To quantify glucose, blood samples were collected before the exercise, every three minutes along the 30 minutes of physical activity, and five and 10 minutes after finishing the exercise. For the downward slope, there was a homogeneous group behavior for blood glucose dynamics during the exercise, which was characterized by a monotonic decrease of glucose levels until reaching a minimum value at experimental times between 20 and 30 min, followed by a progressive recovery toward initial values. For the acclivity condition, blood glucose dynamics did not follow such a homogeneous behavior. A set of different types of dynamics could be identified. Experimental data showed that the type of dynamics could be predicted, to some extent, by the basal blood glucose level of subjects. The type of floor slope (upward or downward) directly affected glycolytic consumption and kinetics for the individuals analyzed.

Cooling Kinetic Characteristics of Temperature Difference between Cadaver Temperature and Ambient Temperature / 法医学杂志

OBJECTIVES@#To study the cooling reaction kinetic characteristics of the temperature difference between cadaver temperature and ambient temperature (hereinafter referred to as "cadaver temperature difference") according to the reaction kinetics method.@*METHODS@#Thirty rabbits were randomly divided into 5 groups with 6 rabbits in each group. The rabbits were injected with 10% potassium chloride solution intravenously. After death, the rabbits were placed at 5 ℃, 10 ℃, 15 ℃, 20 ℃ and 25 ℃ environment condition, respectively, and the rectal temperature was measured every minute for 20 hours. The measured cadaver temperature was subtracted from ambient temperature, and the cadaver temperature difference data was calculated using the reaction kinetics formula. The linear regression equation was fitted for analysis, and the experimental results were applied to the temperature difference data of human body after death for verification.@*RESULTS@#Under different environmental conditions, the linear coefficient determination of temperature difference -ln(C/C0) in rabbits was 0.99, showing a good linear relationship with time t. The application of human body temperature data after death was consistent with the results of animal experiments.@*CONCLUSIONS@#Under stable conditions, the temperature difference cooling process after death in rabbits is a first-order kinetic response. The method can also be used to study the temperature difference in human body after death.

Kinetics of MDSC in Patients Treated Steroids-Ruxolitinib as the First Line Therapy for aGVHD / 中国实验血液学杂志

OBJECTIVE@#To analyze the kinetic characteristics of lymphocyte subsets and myeloid-derived suppressor cell (MDSC) in patients who newly diagnosed intermediate- to high-risk aGVHD and treated with steroids-ruxolitinib as the first line therapy from a single-arm, open clinical trial (NCT04061876).@*METHODS@#We prospectively observed the efficacy of 23 patients having intermediate- to high-risk aGVHD and treated with steroids-ruxolitinib as the first line therapy. The kinetic characteristics of lymphocyte subsets and MDSC were monitored, and then we compared them in steroids-ruxolitinib group (n=23), free-aGVHD group (n=20) and steroids group (n=23).@*RESULTS@#Of the 23 patients, the CR rate was 78.26% (18/23) on day 28 after first-line treatment with steroids-ruxolitinib. On day 28 after treatment, patients had lower level of CD4+CD29+ T cells (P=0.08) than that of pre-treatment, whereas levels of other lymphocyte subsets in this study were higher than that of pre-treatment; CD4+CD29+ T cells in CR patients decreased, compared with refractory aGVHD patients. On day 28 of treatment, CD8+CD28- T cells (P=0.03) significantly increased in patients with aGVHD than that in patients without aGVHD, so did CD8+CD28- T / CD8+CD28+ T cell ratio (P=0.03). Compared with patients without aGVHD, patients with aGVHD had lower level of G-MDSC, especially on day 14 after allo-HSCT (P=0.04). Compared with pre-treatment, M-MDSC was higher in CR patients on day 3 and 7 post-treatment (P3=0.01, P7=0.03), e-MDSC was higher on day 28 post-treatment (P=0.01). Moreover, compared with CR patients, M-MDSC was lower in refractory aGVHD patients on day 3 post-treatment (P=0.01) and e-MDSC was lower on day 28 post-treatment (P=0.01). Compared with steroids group, MDSC in steroids-ruxolitinib group was higher, with the most significant difference in M-MDSC (P3=0.0351; P7=0.0142; P14=0.0369).@*CONCLUSION@#We found that patients newly diagnosed intermediate- to high-risk aGVHD receiving first-line therapy with steroids-ruxolitinib achieved high response rate. Moreover, the novel first-line therapy has a small impact on the immune reconstitution of patients after allo-HSCT. Elevated MDSC might predict a better response in aGVHD patients receiving this novel first-line therapy. M-MDSC responded earlier to steroids-ruxolitinib than e-MDSC, G-MDSC.

Water migration and kinetics of Arecae Semen during moistening process / 中国中药杂志

In this study, low-field nuclear magnetic resonance(LF-NMR) and magnetic resonance imaging(MRI) were employed to analyze the water distribution, status, and migration in the moistening process of Arecae Semen. Peleg model was adopted to study the water absorption kinetics of Arecae Semen moistened at different water temperatures(10, 30, and 50 ℃). The Arecae Semen samples soaked at different water temperatures all contained four water states: binding water T_(21), non-flowing water T_(22), free water T_(23), and unbound water T_(24). Non-flowing water had the largest increase in peak area during the moistening process, followed by free water. The peak areas of non-flowing water, free water, and total water were correlated with the water content(P<0.01). Therefore, LF-NMR can quickly and non-destructively predict the water content of Arecae Semen during moistening. The peak area of non-flowing water and the content of free water were correlated with the content of arecoline in the soaking solution(P<0.01), which indicated that the faster flow of non-flowing water and more free water corresponded to more arecoline dissolved. The MRI images showed that the water migration pathway varied at different soaking temperatures, and the moistening degree obtained by this means was consistent with that obtained based on traditional experience. The rate constant K_1 fitted by Peleg model decreased with the increase in water temperature, while the capacity constant K_2 showed an opposite trend. The Arrhenius equation fitting of K_1 with temperature showed that the activation energy of Arecae Semen in the moistening process was 32.98 kJ·mol~(-1). LF-NMR/MRI can be used to analyze the water status and content and determine the end moisturing point of Arecae Semen. Peleg model can accurately describe the water absorption properties of Arecae Semen in the moistening process. The findings of this study can guide the moistening optimization and mechanism research of other seed Chinese medicinal materials.

Kinetics and variation of volatile components of Atractylodis Macrocephalae Rhizoma during hot-air drying / 中国中药杂志

The present study explored the kinetics and variation of volatile components of Atractylodis Macrocephalae Rhizoma during the hot-air drying process to obtain the optimal process parameters under multiple goals such as drying efficiency and drying quality. The dry basis moisture content and drying rate curves along with the change of drying time of Atractylodis Macrocephalae Rhizoma were investigated at five levels of drying air temperatures(30, 40, 50, 60, and 70 ℃). The relationship between moisture ratio and time in the drying process of Atractylodis Macrocephalae Rhizoma was fitted and verified by Midilli model, Page model, Overhults model, Modified Page model, Logaritmic model, Two terms Exponential model, and Newton model. Meanwhile, the effective diffusion coefficient of moisture(D_(eff)) and activation energy(E_a) in Atractylodis Macrocephalae Rhizoma were calculated under different drying air temperatures. GC-MS was used to determine the volatile components and content changes of the fresh Atractylodis Macrocephalae Rhizoma and dried products at different temperatures. The dry basis moisture content and drying rate of Atractylodis Macrocephalae Rhizoma were closely related to the temperature of the drying medium, and the moisture of the Atractylodis Macrocephalae Rhizoma decreased with the prolonged drying time. As revealed by the drying rate curve, the drying rate increased with the increase in hot air temperature, and the migration of moisture was accelerated. The comparison of the correlation coefficient(R~2), chi-square(χ~2), and root mean standard error(RMSE) of each model indicated that the parameter average of the Midilli model had the highest degree of fit, with R~2=0.999 2, χ~2=8.78×10~(-5), and RMSE=8.20×10~(-3). Besides, the D_(eff) at 30-70 ℃ was in the range of 1.04×10~(-9)-6.28×10~(-9) m~2·s~(-1), and E_a was 37.47 kJ·mol~(-1). The volatile components of fresh Atractylodis Macrocephalae Rhizoma and dried products at different temperatures were determined by GC-MS, and 18, 18, 18, 17, 17, and 18 compounds were identified respectively, which accounted for more than 84.76% of the volatile components. In conclusion, the hot-air drying of Atractylodis Macrocephalae Rhizoma can be model-fitted and verified and the variation law of the moisture and volatile components of Atractylodis Macrocephalae Rhizoma with temperature is obtained. This study is expected to provide new ideas for exploring the drying characteristics and quality of aromatic Chinese medicine.

Engineering the 182 site of cyclodextrin glucosyltransferase for glycosylated genistein synthesis / 生物工程学报

Genistein and its monoglucoside derivatives play important roles in food and pharmaceuticals fields, whereas their applications are limited by the low water solubility. Glycosylation is regarded as one of the effective approaches to improve water solubility. In this paper, the glycosylation of sophoricoside (genistein monoglucoside) was investigated using a cyclodextrin glucosyltransferase from Penibacillus macerans (PmCGTase). Saturation mutagenesis of D182 from PmCGTase was carried out. Compared with the wild-type (WT), the variant D182C showed a 13.42% higher conversion ratio. Moreover, the main products sophoricoside monoglucoside, sophoricoside diglucoside, and sophoricoside triglucoside of the variant D182C increased by 39.35%, 56.05% and 64.81% compared with that of the WT, respectively. Enzymatic characterization showed that the enzyme activities (cyclization, hydrolysis, disproportionation) of the variant D182C were higher than that of the WT, and the optimal pH and temperature of the variant D182C were 6 and 40℃, respectively. Kinetics analysis showed the variant D182C has a lower Km value and a higher kcat/Km value than that of the WT, indicating the variant D182C has enhanced affinity to substrate. Structure modeling and docking analysis demonstrated that the improved glycosylation efficiency of the variant D182C may be attributed to the increased interactions between residues and substrate.

Inhibition of Escherichia coli nitroreductase by the constituents in Syzygium aromaticum / 中国天然药物

Gut bacterial nitroreductases play an important role in reduction of various nitroaromatic compounds to the corresponding N-nitroso compounds, hydroxylamines or aromatic amines, most of which are carcinogenic and mutagenic agents. Inhibition of gut nitroreductases has been recognized as an attractive approach for reducing mutagen metabolites in the colon, so as to prevent colon diseases. In this study, the inhibitory effects of 55 herbal medicines against Escherichia coli(E. coli) nitroreductase (EcNfsA) were examined. Compared with other herbal extracts, Syzygium aromaticum extract showed superior inhibitory potency toward EcNfsA mediated nitrofurazone reduction. Then, the inhibitory effects of 22 major constituents in Syzygium aromaticum against EcNfsA were evaluted. Compared with other tested natural compounds, ellagic acid, corilagin, betulinic acid, oleanic acid, ursolic acid, urolithin M5 and isorhamnetin were found with strong to moderate inhibitory effect against EcNfsA, with IC50 values ranging from 0.67 to 28.98 mol·L-1. Furthermore, the inhibition kinetic analysis and docking simulation demonstrated that ellagic acid and betulinic acid potently inhibited EcNfsA (Ki < 2 μmol·L -1) in a competitively inhibitory manner, which created strong interactions with the catalytic triad of EcNfsA. In summary, our findings provide new scientific basis for explaining the anti-mutagenic activity of Syzygium aromaticum, where some newly identified EcNfsA inhibitors can be used for developing novel agents to reduce the toxicity induced by bacterial nitroreductase.

Expression and characterization of a bifunctional thermal β-glucosidase IuBgl3 from thermophilic archaeon Infirmifilum uzonense / 生物工程学报

β-glucosidase has important applications in food, medicine, biomass conversion and other fields. Therefore, exploring β-glucosidase with strong stability and excellent properties is a research hotspot. In this study, a GH3 family β-glucosidase gene named Iubgl3 was successfully cloned from Infirmifilum uzonense. Sequence analysis showed that the full length of Iubgl3 was 2 106 bp, encoding 702 amino acids, with a theoretical molecular weight of 77.0 kDa. The gene was cloned and expressed in E. coli and the enzymatic properties of purified IuBgl3 were studied. The results showed that the optimal pH and temperature for pNPG hydrolysis were 5.0 and 85 ℃, respectively. The enzyme has good thermal stability, and more than 85% of enzyme activity can be retained after being treated at 80 ℃ for2 h. This enzyme has good pH stability and more than 85% of its activity can be retained after being treated at pH 4.0-11.0 for 1 h. It was found that the enzyme had high hydrolysis ability to p-nitrophenyl β-d-glucoside (pNPG) and p-nitrophenyl β-d-xylopyranoside (pNPX). When pNPG was used as the substrate, the kinetic parameters Km and Vmax were 0.38 mmol and 248.55 μmol/(mg·min), respectively, and the catalytic efficiency kcat/Km was 6 149.20 s-1mmol-1. Most metal ions had no significant effect on the enzyme activity of IuBgl3. SDS completely inactivated the enzyme, while EDTA increased the enzyme activity by 30%. This study expanded the β-glucosidase gene diversity of the thermophilic archaea GH3 family and obtained a thermostable acid bifunctional enzyme with good industrial application potential.

Studies on the enzymatic specificity of diguanylate cyclases domains and the production of new second messengers / Estudos na especificidade enzimática de diguanilato ciclases e na produção de novos segundos mensageiros

In the first chapter, studies on substrate recognition and enzymatic activity of GGDEF domains are presented. Many proteins containing GGDEF domains are diguanylate cyclases (DGCs, EC 2.7.7.65), enzymes that catalyze the conversion of 2 GTP molecules into the second messenger c-di-GMP in prokaryotes. This molecule is primarily implicated in the transition between motile and sessile lifestyles, as well several other phenotypes. Redundancy and diversity of GGDEF domain sequences in many bacterial genomes raises the possibility that other enzymatic functions may yet be discovered. To test this hypothesis, i) the effect of point mutations on the structure and enzymatic activity of GGDEF domains is analyzed, ii) the enzymatic specificity of wild-type GGDEF domains from different proteins is also tested, and iii) when non-canonical products are detected, enzymatic models are studied to understand its preferential production. The principal results obtained from these studies are as follows. Seven mutants of the DGC PleD (a GGDEF containing-protein from Caulobacter crescentus) were constructed and the crystallographic structure of two of them was solved, showing that they are unlikely to bind the guanine moiety in its active site. Additionally, five mutants of XAC0610, another DGC from Xanthomonas citr, were constructed and their substrate specificities were evaluated. None of those mutants were able to use ATP as a substrate. Finally, seven different GGDEF domain-containing DGCs from different sources were expressed and purified and their enzymatic specificities were tested with several nucleotide triphosphates. One enzyme, GSU1658 from Geobacter sulfurreducens was particularly promiscuous and shown to produce c-di-GMP, c-di-AMP, c-di-IMP, c-di-2´dGMP, cGAMP, c-GIMP, and c-AIMP. Interestingly, XAC0610 was able to recognize 2´dGTP as substrate. Analysis of enzyme kinetics of XAC0610 in presence of 2´dGTP and/or GTP showed the preferential formation of the hybrid linear product pppGp2´dG. The second chapter present studies on cyanide metabolism in Bacillus with focus on the cyanide dihydratase of Bacillus safensis. Cyanide is widely used in industries due to its high affinity for metals. This same ability confers potent toxicity to this compound. Thus, industries must reduce the cyanide concentration from wastewater before its final disposal. Physical, chemical, and biological methods have been developed to achieve this goal, but knowledge about metabolic pathways and the biology of enzymes involved in cyanide degradation is still scarce. Here, the isolation of a Bacillus safensis strain from mine tailings in Peru is described. Classification of this strain was done through a comparative analysis of 132 core genomes of strains from the Bacillus pumilus group. Sequence analysis determined that a cyanide dihydratase (CynD, EC 3.5.5.1)) encoded in the genome of the isolated strain was likely the enzyme responsible for cyanide degradation. Confirmation of the cyanide degrading activity of CynD from this strain was achieved by cloning, expression and purification of the enzyme and its enzymatic characterization. CynD from this strain was active up to pH 9 and oligomerization patterns analyzed by SEC-MALS and electron microscopy showed that the enzyme forms large helical structures at pH 8 and smaller structures at higher pHs. Finally, we show that CynD expression is strongly induced in the presence of cyanide. The last two years of graduate studies were carried out in the context of the COVID-19 pandemic. Thanks to the large amount of publicly available genomic data, we were able to carry out studies on the worldwide dynamics of the spread of SARS-CoV-2 mutants forms. In the first year of the pandemic, genomic classification of 171,461 genomes showed the presence of five major haplotypes based on nine mutations. The worldwide distribution and the temporal evolution of frequency of these haplotypes was carefully analyzed. All the haplotypes were identified in the six regions analyzed (South America, North America, Europe, Asia, Africa, and Oceania); however, the frequency of each of them was different in each of these regions. As of September 30, 2020, haplotype 3 (or operational taxonomic unit 3, OTU_3) was the most prevalent in four regions (South America, Asia, Africa, and Oceania). OTU_5 was the most prevalent in North America and OTU_2 in Europe. Temporal dynamics of the haplotypes showed that OTU_1 became nearly extinct after 8 months of pandemic (November 2020). Other OTUs are still present in different frequencies all around the world, while currently generating new variants. Based on their temporal dynamics, a classification scheme of 115 SARS-CoV-2 mutations identified from 1,058,020 SARS-COV-2 genomes was also performed. Three types of temporal dynamics of mutations were identified: i) High-Frequency mutations are characterized by a rapid increase in frequency upon its appearance, ii) medium and iii) low-frequency mutations maintain mid or low-frequencies for several months and can be region-specific. Finally, we performed a correlation analysis of the effective reproduction number (Rt) of SARS-CoV-2 harboring the high-frequency mutation N501Y with the level of control measures adopted in specific jurisdictions. We show that Rt is negatively correlated with the level of control measures in eight of the nine countries analyzed. This negative correlation was similar when we analyzed the Rt of SARS-CoV-2 not-harboring N501Y. Thus, the control measures likely diminish the Rt of both SARSCoV-2 wild-type and N501Y

O presente trabalho está dividido em três capítulos sobre linhas de pesquisa diferentes desenvolvidas pelo autor durante o período de doutorado No primeiro capítulo, são apresentados estudos relacionados ao reconhecimento estrutural de substratos e análise enzimática de domínios GGDEF com atividade diguanilato ciclase (EC 2.7.7.65). As proteínas contendo domínios GGDEF estão relacionados à produção enzimática do segundo mensageiro c-di-GMP, a partir de duas moléculas de GTP, em procariotos. Esta molécula está principalmente envolvida na transição entre os estilos de vida móveis e sésseis, bem como vários outros fenótipos. Redundância e diversidade de sequências de domínio GGDEF aumentam a possibilidade de que outras funções enzimáticas ainda possam ser descobertas. Para testar esta hipótese, i) o efeito de mutações pontuais na estrutura e atividade enzimática dos domínios GGDEF é analisado, ii) a especificidade enzimática de domínios GGDEF de enzimas diferentes também é testada e iii) quando produtos não canônicos são detectados, modelos enzimáticos são estudados para entender sua produção preferencial. Como resultados mais importantes, sete mutantes do PleD (uma proteína contendo GGDEF) foram construídos e a estrutura cristalográfica de dois delas foi resolvida, mostrando que é improvável que eles liguem à porção guanina em seu sítio ativo. Além disso, cinco mutantes da proteína XAC0610 de Xanthomonas citri foram construídos e sua capacidade de usar ATP ou GTP como substrato foi avaliada. Nenhum desses mutantes foi capaz de usar ATP como substrato. Finalmente, sete outras proteínas contendo GGDEF foram purificadas e sua especificidade enzimática foi avaliada com vários trifosfatos de nucleotídeos. Uma enzima promíscua chamada GSU1658 mostrou produzir c-di-GMP, c-di-AMP, c-di-IMP, c-di-2´dGMP, c-GAMP, cGIMP e c-AIMP. Curiosamente, o XAC0610 foi capaz de reconhecer 2´dGTP como substrato. A análise da cinética enzimática de XAC0610 na presença de 2´dGTP e GTP mostrou a formação preferencial do produto linear híbrido pppGp2´dG. O segundo capítulo aborda estudos sobre o metabolismo do cianeto em Bacillus com foco na cianeto dihidratase de Bacillus safensis. O cianeto é amplamente utilizado nas indústrias devido à sua alta afinidade com os metais. Esta mesma capacidade confere toxicidade potente a este composto. Assim, as indústrias têm que reduzir a concentração de cianeto das águas residuais antes de sua disposição final. Métodos físicos, químicos e biológicos têm sido desenvolvidos para atingir esse objetivo, mas o conhecimento sobre as vias metabólicas e a biologia das enzimas envolvidas na degradação do cianeto ainda é escasso. Aqui, é descrito o isolamento de uma cepa de Bacillus safensis de rejeitos de minas no Peru. A classificação desta cepa foi feita através de uma análise comparativa de 132 core genomes de cepas do grupo de Bacillus pumilus. Em seguida, determinamos que uma cianeto dihidratase (CynD, EC 3.5.5.1) codificada no genoma da cepa isolada era provavelmente a enzima responsável pela degradação do cianeto. A confirmação da atividade degradante de cianeto de CynD desta cepa foi feita por clonagem, expressão e purificação da enzima e realização de caracterização enzimática. O CynD desta cepa é ativo até pH 9 e os padrões de oligomerização analisados por SEC-MALS mostraram que a enzima forma longas estruturas helicoidais em pH 8 e estruturas menores enquanto o pH aumenta. Finalmente, foi demonstrado que a expressão de CynD é fortemente induzida na presença de cianeto. Os últimos dois anos do doutorado foram realizados no contexto da pandemia COVID- 19. Vários laboratórios se dedicaram a gerar conhecimento para ajudar no combate à pandemia. Nesta situação e graças à grande quantidade de dados genômicos disponíveis publicamente, estudos sobre a dinâmica das mutações do SARS-CoV-2 foram realizados. No primeiro ano da pandemia, a classificação genômica de 171.461 genomas mostrou a presença de cinco haplótipos principais com base em nove mutações. A distribuição mundial e a mudança de frequência desses haplótipos foram analisadas cuidadosamente. Todos os haplótipos foram identificados nas seis regiões analisadas (América do Sul, América do Norte, Europa, Ásia, África e Oceania); no entanto, a frequência de cada um deles foi diferente em cada uma dessas regiões. Em 30 de setembro de 2020, o haplótipo 3 (ou unidade taxonômica operacional 3, OTU_3) era o mais prevalente em quatro regiões (América do Sul, Ásia, África e Oceania). OTU_5 foi o mais prevalente na América do Norte e OTU_2 na Europa. A dinâmica temporal dos haplótipos mostrou que OTU_1 parece perto da extinção após 8 meses de pandemia (novembro de 2020). Outros OTUs ainda estão presentes em diferentes frequências em todo o mundo, mesmo atualmente gerando novas variantes. Com base em sua dinâmica temporal, um esquema de classificação de 115 mutações SARS-CoV-2 identificadas a partir de 1.058.020 genomas SARS-COV-2 também foi feito. Três tipos de dinâmica temporal de mutações foram identificados: i) Mutações de alta frequência, ii) mutações de média frequência e iii) mutações de baixa frequência. Finalmente, foi analisada a correlação do número de reprodução efetiva (Rt) do SARS-CoV-2 que contém a mutação de alta frequência N501Y com o nível de medidas de controle, mostrando que seu Rt está negativamente correlacionado com o nível de medidas de controle em oito dos nove países analisados. Esta correlação negativa foi semelhante quando foi analisado o Rt de SARS-CoV-2 sem a mutação N501Y. Assim, as medidas de controle provavelmente diminuirão o Rt de SARS-CoV-2 tipo selvagem e N501Y

The influence of subtalar axis orientation on the foot posture of older adults in a closed kinetic chain / A influência da orientação do eixo subtalar na postura do pé de idosos em cadeia cinética fechada

Objectives: This study compared the influence of subtalar axis position on foot behavior in a closed kinetic chain in older and younger adults. Methods: The sample included 50 older adults and a control group of 50 younger adults. The variables were initially analyzed for both feet together, and were later analyzed separately, comparing each foot (right and left) between groups. Range of motion was assessed by validated goniometric procedures: the position of subtalar axis was evaluated by the palpation technique, while the Foot Posture Index was used to assess behavior in a closed kinetic chain. Student's t-test / Mann-Whitney test compared the main variables according to sample distribution, while Student's t-test / Wilcoxon test was used for paired samples. A standardized Haberman residuals test was also used to determine the connection between the position of subtalar joint axis and the Foot Posture Index. Results: Data from the right and left feet were similar for all variables. The older group had reduced mobility in the ankle and first metatarsophalangeal joint (5.42º [SD (Standard Deviation), 4.49] and 76.12º [SD, 19.24], respectively) with statistically significant values, (p <0.001), as measured by the Mann-Whitney test for the ankle joint and the t-Sutdent test for the first metatarsophalangeal joint, while the younger group had normal values (11.46º [SD, 6.49] and 97.17º [SD, 13.65], respectively)(p < 0.001). The difference in subtalar axis position was not significant (p = 0.788), with more internal deviations in both groups. There was a significant difference in Foot Posture Index (p = 0.006, by applying the chi-square test), with the normal position more prevalent in the older group and the prone position more prevalent in the younger group. Conclusions: Regarding internal deviations in the subtalar joint axis, the older group had a higher frequency of feet in the normal position, while the younger group had a higher frequency of feet in the prone position which, in this case, agrees with the rotational balance theory. For the normal axis position, a higher frequency of normal position was found in both groups. Regarding external deviations of the subtalar joint axis, neither group followed the pattern expected in rotational balance theory. The most consistent connection in the older group was between external axis position and supine foot position, whereas in the younger group it was between normal axis position and normal foot position.

Objetivos: Este estudo comparou a influência da posição do eixo subtalar no comportamento do pé em cadeia cinética fechada em idosos e adultos jovens. Metodologia: O grupo amostral incluiu 50 idosos e o grupo controle, 50 adultos jovens. As variáveis foram estudadas inicialmente para ambos os pés e comparadas entre os grupos, sendo posteriormente analisadas separadamente, comparando-se cada pé (direito e esquerdo) entre os grupos. A amplitude de movimento articular foi avaliada por procedimentos goniométricos validados; a posição do eixo subtalar foi avaliada pela técnica de palpação; o Foot Posture Index foi utilizado para avaliar o comportamento do pé em uma cadeia cinética fechada. O teste t de Student/teste de Mann-Whitney comparou as principais variáveis de acordo com a distribuição amostral, enquanto o teste t de Student/teste de Wilcoxon foi utilizado para amostras emparelhadas. O teste de resíduais ajustados de Haberman padronizado foi usado para a relação entre a posição do eixo da subtalar e o Foot Posture Index. Resultados: Os dados dos pés direito e esquerdo foram semelhantes para todas as variáveis. O grupo mais velho apresentou mobilidade reduzida no tornozelo e na primeira articulação metatarsofalângica (5,42 [desvio padrão ­ DP, 4,49] e 76,12 [DP, 19,24] graus, respectivamente), enquanto o grupo mais jovem apresentou valores normais (11,46 [DP, 6,49] e 97,17 [DP, 13,65], respetivamente) com valores estatisticamente significativos, (p <0,001), aferidos pelo teste de Mann-Whitney para a articulação do tornozelo e pelo teste t-Sutdent para a primeira articulação metatarsofalângica. A diferença na posição do eixo subtalar não foi significativa (p = 0,788, pela aplicação do teste de Qui-quadrado), com mais desvios internos em ambos os grupos. O Foot Posture Index diferiu significativamente entre os grupos (p = 0,006 pela aplicação do teste de Qui-quadrado), sendo a postura normal mais prevalente no grupo mais velho e a postura pronada mais prevalente no grupo mais jovem. Conclusões: Em relação aos desvios internos do eixo da articulação subtalar, o grupo mais velho apresentou maior frequência de pés na postura normal, enquanto o mais jovem apresentou maior frequência de pés pronados, o que, neste caso, corrobora a teoria do equilíbrio rotacional. Na posição normal do eixo, foi encontrada maior frequência de pés com postura normal em ambos os grupos. Em relação aos desvios externos do eixo da articulação subtalar, nenhum dos grupos seguiu o padrão esperado na teoria do equilíbrio rotacional. A relação mais consistente no grupo mais velho foi entre a posição do eixo externo e a posutra supinada do pé, enquanto no grupo mais jovem se deu entre a posição normal do eixo e a postura normal do pé

Formulation of stomach-specific floating microparticles of nizatidine and their radiographic evaluation

Nizatidine is an anti-secretogogue and a gastroprotective drug with a half-life of 1-2 h and is well absorbed in the stomach. This study aimed to optimize the process and develop floating microparticles of nizatidine that are based on low methoxyl pectin. Oil-in-oil dispersion method and Taguchi orthogonal array design were employed, and the prolonged residence time of the microparticles in the stomach was demonstrated. The constraints for independent variables, viz. A-polymer, B-internal solvent volume, C-surfactant, D-stirring rate and E-stirring time were set to generate the experimental runs. Particle size, percentage yield, micromeritic properties, entrapment efficiency, in vitro buoyancy and in vitro release were characterized. Surface morphology, zeta potential, in vitro release kinetics and in vivo floating performance of the optimized formulation was examined. The microparticles were free-flowing, irregular in shape and had a mean particle size distribution of 73-187 µ. Low methoxyl pectin played a predominant role in achieving buoyancy and optimum gastric retention for the modified release of the drug, suggesting Korsmeyer-Peppas model as the possible release mechanism. In vivo radiographic study in rabbits revealed that the drug was retained in the stomach for a period of 6 h. These results indicate that nizatidine floating microparticulate system provides modified drug release for the effective treatment of gastric ulcer

Optimization of Diltiazem hydrochloride osmotic formulation using QBD approach

Abstract Diltiazem hydrochloride (DLH) is a calcium channel blocker useful for the treatment of angina pectoris, arrhythmia, and hypertension. DLH having a short half-life needs frequent administration for successful treatment but this poses a problem of poor patient compliance. These requirements are served by elementary osmotic pump tablets (EOP) based controlled-release (CR) systems. Quality by design (QbD) approach assists in screening various factors with subsequent assessment of critical parameters that can have a major impact on the scalability of EOP. Tablets were formulated using wet granulation method followed by osmotic coating. Factorial design based QbD strategy aided in defining the risk assessment of influential variables such as hydrophilic polymers and osmotic coat component on the in-vitro release kinetics of the designed EOP tablets. These formulated EOP systems followed zero-order kinetics, a characteristic feature of EOPs. EOP tablets were formulated applying a systematic QbD statistical approach. The formulated DLH EOP systems with improved concentration-independent behavior helped to address the challenges of IR formulation. Application of QbD strategy in ascertaining the scalability of DLH EOP formulation would help pharmaceutical industries in the translation of EOP based drug delivery systems from R&D to market.

Momento aductor de la cadera durante la marcha en adultos mayores asintomáticos / Hip adductor moment during gait in asymptomatic older adults

Resumen Introducción: El momento articular durante la marcha se ha relacionado con diferentes procesos clínicos en la población adulto mayor, en Colombia no se cuentan con reportes propios. Objetivo: Analizar el momento aductor de la cadera durante la marcha de adultos mayores asintomáticos. Materiales y métodos: Se evaluó a 110 participantes siguiendo las referencias del software VICON NEXUS 2.8.1 modelo Full Body, se utilizó 2 plataformas de fuerza y el volumen de captura estuvo delimitado por 8 cámaras opto eléctricas Bonita 10. Se incluyó variables antropométricas, sociodemográficas, espaciotemporales y cinéticas durante la fase de apoyo, resaltando los dos picos máximos del momento aductor. Resultados: Las cifras del Pico Momento Aductor 1 y 2 (PMA1 y PMA2) fueron de 0,76 y 0,70 Nm/Kg respectivamente, estos picos se relacionaron con masa, talla e índice de masa corporal. Se construyó así una referencia para el análisis de adultos mayores asintomáticos. Conclusiones: La gráfica del momento aductor de la cadera es similar a la descrita por otros investigadores, pero en menor magnitud que en la población sintomática de coxartrosis.

Abstract Introduction: Although joint moment during waking has been associated with different clinical processes in the elderly population, there is a lack of reports in Colombia. Objective: To analyze the hip adductor moment during gait in asymptomatic older adults. Materials and methods: 110 participants were assessed using the VICON NEXUS 2.8.1. Full Body model software. 2 force platforms were used and the capture volume was delimited through 8 Bonita-10 optoelectronic cameras. Anthropometric, sociodemographic, spatiotemporal, and kinetic variables were included during the support phase, highlighting the two maximum peaks of the adductor moment. Results: The figures for Adductor Moment Peaks 1 and 2 (AMP1 and AMP2) were 0.76 and 0.70 Nm/Kg, respectively, which were related to mass, height and body mass index. Thus, a reference for the analysis of asymptomatic older adults was developed. Conclusion: The hip adductor moment graph is similar to that described by other researchers, but to a lesser extent than the values seen in coxarthrosis symptomatic population.

Scientific training of sports medicine for balance of knee joint muscle strength of athletes / Treinamento científico de medicina esportiva para equilíbrio da força muscular da articulação do joelho de atletas / Entrenamiento científico de la medicina deportiva para el equilibrio de la fuerza muscular de la articulación de la rodilla de los atletas

ABSTRACT Introduction: As skiers need to complete their movements in high mountains and snow, the athlete's landing's stability is directly related to the movement's success. The stable landing action wins high scores for the athletes' participating actions and protects their safety. Objective: This article analyzes the characteristics of lower limb muscle strength and static balance ability of female freestyle skiing aerials athletes to provide athletes with targeted strength training, evaluation of muscle effects after training, and athlete selection to provide a scientific basis valuable Theoretical reference. Methods: The paper uses isokinetic testing and balance testing methods to study the characteristics of the hip and knee flexor and extensor strengths of the Chinese great female freestyle skiing aerials athletes and the static balance characteristics in four standing positions. Results: The right flexor-extensor force, flexor-extensor force ratio, and average power value of the right hip joint were slightly greater than the left flexor power. The left and right knee joint extensor unit peak weight moments and the left and right average power values were all four indicators. Greater than the flexor, at different test speeds of 60°/s (slow speed) and 240°/s (fast), the peak flexion and extension torque per unit weight, the average power of flexion and extension, the force of flexion and extension, and the average power appear with the increase of the test speed as a significant difference. Conclusions: The research in the thesis recommends reasonable weight control and balanced training of muscle strength, using the condition of moderately increasing exercise speed, to strengthen the training of lower limb extensor strength, provide targeted strength training for athletes, evaluate the muscle effect after training and providing the scientific basis and valuable theoretical reference. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Introdução: Como os esquiadores precisam completar seus movimentos em altas montanhas e neve, a estabilidade de pouso do atleta está diretamente relacionada ao sucesso do movimento. A ação de pouso constante ganha altas pontuações para os participantes e protege sua segurança. Objetivo: este artigo discute as características da força muscular das extremidades inferiores e habilidade de equilíbrio estático de atletas de esqui estilo livre para fornecer aos atletas treinamento de força específico e avaliação pós-treino dos efeitos musculares em atletas selecionados para fornecer uma base científica de referência teórica valiosa. Métodos: O artigo usa testes isocinéticos e métodos de teste de equilíbrio para estudar as características de força dos flexores e extensores de quadril e joelho de grandes atletas chinesas de esqui estilo livre e as características de equilíbrio estático em quatro posições de pé. Resultados: A força flexor-extensora direita, a relação da força flexor-extensora e o valor médio da potência da articulação do quadril direito foram ligeiramente maiores do que a potência do flexor esquerdo. Os momentos máximos de peso da unidade extensora da articulação do joelho esquerdo e direito e os valores médios das potências esquerda e direita foram os quatro indicadores. Maior que o flexor, em diferentes velocidades de teste de 60 ° / s (velocidade lenta) e 240 ° / s (rápido), o torque máximo de flexão e extensão por unidade de peso, a força média de flexão e extensão, a força de flexão e extensão, e a potência média aparece com o aumento da velocidade de teste como uma diferença significativa. Conclusões: A pesquisa na tese recomenda o controle de peso razoável e o treinamento de força muscular balanceado, utilizando a condição de aumentar moderadamente a velocidade do exercício, para fortalecer o treinamento de força extensora de membros inferiores, fornecer treinamento de força específico para atletas, avaliando o efeito muscular após formar e fornecer a base científica e um valioso referencial teórico. Nível de evidência II; Estudos terapêuticos- investigação dos resultados do tratamento.

RESUMEN Introducción: Como los esquiadores necesitan completar sus movimientos en alta montaña y nieve, la estabilidad del aterrizaje del atleta está directamente relacionada con el éxito del movimiento. La acción de aterrizaje estable gana puntuaciones altas para las participantes y protege su seguridad. Objetivo: Este artículo analiza las características de la fuerza muscular de las extremidades inferiores y la capacidad de equilibrio estático de las atletas de esquí de estilo libre para proporcionar a los atletas un entrenamiento de fuerza específico y una evaluación de los efectos musculares después del entrenamiento en atletas seleccionados para proporcionar una base científica de referencia teórica valiosa. Métodos: El artículo utiliza pruebas isocinéticas y métodos de prueba de equilibrio para estudiar las características de la fuerza de los flexores y extensores de cadera y rodilla de las grandes atletas chinas de esquí de estilo libre femenino y las características del equilibrio estático en cuatro posiciones de pie. Resultados: La fuerza flexora-extensora derecha, la relación de fuerza flexora-extensora y el valor de potencia promedio de la articulación de la cadera derecha fueron ligeramente mayores que la potencia del flexor izquierdo. Los momentos de peso máximo de la unidad extensora de la articulación de la rodilla izquierda y derecha y los valores de potencia promedio izquierda y derecha fueron los cuatro indicadores. Mayor que el flexor, a diferentes velocidades de prueba de 60 ° / s (velocidad lenta) y 240 ° / s (rápido), el par máximo de flexión y extensión por unidad de peso, la potencia promedio de flexión y extensión, la fuerza de flexión y extensión, y la potencia media aparecen con el aumento de la velocidad de prueba como una diferencia significativa. Conclusiones: La investigación en la tesis recomienda un control de peso razonable y un entrenamiento equilibrado de la fuerza muscular, utilizando la condición de aumentar moderadamente la velocidad del ejercicio, para fortalecer el entrenamiento de la fuerza extensora de las extremidades inferiores, proporcionar entrenamiento de fuerza específico para los atletas, evaluar el efecto muscular después del entrenamiento y proporcionar la base científica y una valiosa referencia teórica. Nivel de evidencia II; Estudios terapéuticos- investigación de los resultados del tratamiento.