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STUDIES ON THE RELATIONSHIP BETWEEN THE PATHOGENICITY OF PARACOCCIDIOIDES-BRASILIENSIS IN MICE AND ITS GROWTH-RATE UNDER DIFFERENT OXYGEN ATMOSPHERES

Sano, A.; Miyaji, M.; Nishimura, K.; Defranco, M. F.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica Formato: 93-101
ENG
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65.88%
We performed comparative studies of the pathogenicity of six strains of Paracoccidioides brasiliensis (Bt-9, Bt-4, Pb-9, Pb-18, Bt-7 and B-1183) for young adult male ddY mice and growth rate of each strain under different oxygen atmospheres (aerobic, micro-aerobic and anaerobic atmospheres) at 37-degrees-C. 10(6) units of yeast cells were intravenously injected into each mouse. The pathogenicity of each isolate was determined by a scoring system based on organ culture and histopathological findings. The growth rates under different oxygen atmospheres were determined by a scoring system in which 300 fungal units per strain were counted. The strain Bt-9 showed the greatest pathogenicity, followed by Bt-4. Pb-9 and Pb-18 had on intermediate rank of pathogenicity. Bt-7 and B-1183 were the least pathogenic of the strains tested. Except for strain Bt-7 all strains showed an excellent growth under an aerobic atmosphere. Bt-4 and Bt-9 also showed excellent growth under a micro-aerobic atmosphere, followed by Pb-9, whereas the growth of Pb-18, Bt-7 and B-1183 was limited. There was a correlation between the growth rate under a micro-aerobic atmosphere and the pathogenicity of a strain. The growth rate of P. brasiliensis under a micro-aerobic atmosphere strongly correlated to its pathogenicity.

Growth rate of the mounds of Nasutitermes sp. (Isoptera: Termitidae)

Buschini, M. L T; Leonardo, A. M C
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 525-531
ENG
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The growth rate of mounds of Nasutitermes sp. was evaluated by taking monthly measurements of the diameter and the height of ten mounds during twelve months. Through these data, the monthly volumes were calculated for each of them and, later, a dispersion diagram between the volume of each mound and the number of days from the first observation was obtained. From this diagram, it was observed that during the 335 days of observation, the rate of growth of these mounds was null.

Specific growth rate regulation in a simulated fed-batch E. coli fermentation

Rocha, I.; Ferreira, E. C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2006 ENG
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65.88%
The specific growth rate is one of the most important process variables characterizing the state of microorganisms during fermentations mainly because the biosynthesis of many products of interest is often related with the values assumed by this parameter. In the particular case of the fed-batch operation of Escherichia coli for the production of recombinant proteins, it is often argued that both pre- and the post-induction specific growth rates should be closely controlled in order to achieve maximum productivities on the desired recombinant protein. In this work a feedforward-feedback controller was developed with the purpose of regulating the global specific growth rate during a fed-batch fermentation of E. coli. The developed algorithm allows to maintain the cells in two different metabolic regimens (simultaneous oxidative and fermentative growth on glucose or oxidative growth on glucose), depending on the selected setpoint for the controlled variable. The pure open-loop version of the controller revealed a relatively poor performance when dealing with process noise. However, the introduction of on-line measurements of fermenter weight and biomass estimation obtained from asymptotic observers allowed a better approximation between the desired setpoints and the simulated values of the specific growth rates. Finally...

Growth rate variation of the stalked barnacle Pollicipes pollicipes (Crustacea: Cirripedia) using calcein as a chemical marker; Variación de la tasa de crecimiento del percebe Pollicipes pollicipes (Crustacea: Cirripedia) utilizando calceína como marcador químico

Jacinto, D.; Penteado, Nélia; Pereira, Diana; Sousa, Alina; Cruz, Teresa
Fonte: CSIC Publicador: CSIC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
65.88%
This study describes the use of calcein as a chemical tagging methodology to estimate growth rate variation of the stalked barnacle Pollicipes pollicipes, an ecologically important intertidal species and economic resource, in SW Portugal. Calcein tagging had a high success rate (94%) in marking both juvenile and adult barnacles for a period of 2.5 months, pro- viding a valuable method for obtaining reliable data in growth studies of P. pollicipes. Growth rate decreased with barnacle size and was highly variable amongst individuals, particularly in smaller barnacles. No effect of shore level on barnacle growth was detected. Growth rates were higher in smaller juvenile barnacles, peaking at a 1.1-mm monthly increment in rostro-carinal length (RC) for individuals with RC=5 mm, and decreased with barnacle size (monthly growth rates of 0.5 mm for adult barnacles with RC~12.5 mm). Growth rates observed in adults with commercial interest (RC≥18 mm) was <0.25 mm per month. The advantages of tagging P. pollicipes with calcein were the possibility of mass marking individual barna- cles of different size cohorts within a short period (less than 1 day of manipulation); and reduced time of fieldwork, which is very important because this species inhabits very exposed rocky shores.

Growth rate of a terra firme rain forest in Brazilian Amazonia over an eight-year period in response to logging

Carvalho,João Olegário Pereira de; Silva,José Natalino Macedo; Lopes,José do Carmo Alves
Fonte: Instituto Nacional de Pesquisas da Amazônia Publicador: Instituto Nacional de Pesquisas da Amazônia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2004 EN
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This paper deals with growth rates of trees > 5cm dbh over an eight-year period from 257 species at the Tapajós National Forest. The discussion is centred on the behaviour of the forest after logging. Permanent sample plots were established in 1981 and measured at the first time. The area was logged in 1982. Measurements after logging occurred in 1983, 1987 and 1989. Considering all species together, diameter increment was similar for both intensities of logging until five years after logging. Light-demanding species showed significantly higher growth rates than shade-tolerant species in the logged forest, with greater increment in the heavier treatment intensity. Commercial species also had higher growth rates in the heavier logged area, although those were significantly different only in the period from one to five years after logging. In the undisturbed forest, growth rates increased with increasing dbh size. At species level, growth rate varied between and within treatments, as well as between trees within species, depending mainly on degree of canopy opening. The logging favoured the growth of commercial species, chiefly the light-demanders. Therefore, if the same growth conditions continue being given, for example by silvicultural treatments...

Effect of food on immature development, consumption rate, and relative growth rate of Toxorhynchites splendens (Diptera: Culicidae), a predator of container breeding mosquitoes

Dominic Amalraj,D; Sivagnaname,N; Das,PK
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2005 EN
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65.82%
Food utilization by the larvae of Toxorhynchites splendens (Wiedemann) was studied in the laboratory by offering larvae of Aedes aegypti Linnaeus, Anopheles stephensi (Liston), and Culex quinquefasciatus (Say). Quantitative analyses of data indicated that immature development was significantly faster with increase in food availability. The regression analysis showed that the degrees of the relationship between immature duration (Id) and food availability were higher when offered early instars of prey (first and second instars) than late instars. Consumption rate (Cr) of the predator increased with increase in food availability and this relationship was highly significant when larvae of An. stephensi were offered as food. Consumption rate to food level decreased with increase in the age class of the prey. There was a significant negative correlation between Id and Cr. This aspect helps to increase population turnover of T. splendens in a shorter period when the prey is abundant. Conversely, the predator compensated the loss in daily food intake at low food level by extending Id thereby attains the minimum threshold pupal weight for adult emergence. There was an increase in the relative growth rate (RGR) of the predator when An. stephensi was offered as prey and this was related to the high protein content of the prey per body weight. There was a positive correlation between Cr and RGR. This adaptive life characteristic strategy of this predator is useful for mass-rearing for large scale field release programmes in the control of container breeding mosquitoes is discussed.

Artificial family selection based on growth rate in cultivated lines of Litopenaeus vannamei (Decapoda, Penaeidae) from Venezuela

De Donato,Marcos; Ramirez,Raúl; Howell,Chris; Verginelli,Roberto; Orta,Tomás; Cabrera,Saúl; Mata,Enrique; Manrique,Ramón
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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65.94%
We investigated the effects of family selection on the growth rates of four genetic lines of Litopenaeus vannamei, the Pacific white shrimp, from Venezuela. The mean family weight at selection was 16.79 g and the mean growth rate was 0.169 g d-1 at a mean age of 138 days. The mean growth rates per generation were 0.141 g d-1 for the parental generation (P0), 0.173 g d-1 for the F1 and 0.191 g d-1 for the F2. Survival varied from 83.3% to 94.4%. There were statistically significant differences between lines, with lines B and C, growing at higher temperatures and lower salinities, showing the fastest growth. Regression analysis between growth rate and age for each genetic line showed high r² values, but smaller than those shown between growth rate and generation. The mean heritability (h²) estimated for growth rate was 0.25 ± 0.04, with line per generation values ranging from 0.18 to 0.38. The mean heritability for growth rate per line showed some variation but there was no correlation between heritability and growth rate. Females showed a greater gain in growth rate per generation than males due to their faster growth when they were older. This study shows the high potential of these L. vannamei populations for the future of shrimp culture in the Americas.

Saving and Growth in Egypt

Hevia, Constantino; Loayza, Norman
Fonte: Banco Mundial Publicador: Banco Mundial
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55.98%
This study illustrates the mechanisms linking national saving and economic growth, with the purpose of understanding the possibilities and limits of a saving-based growth agenda in the context of the Egyptian economy. This is done through a simple theoretical model, calibrated to fit the Egyptian economy, and simulated to explore different potential scenarios. The main conclusion is that if the Egyptian economy does not experience progress in productivity -- stemming from technological innovation, improved public management, and private-sector reforms -- then a high rate of economic growth is not feasible at current rates of national saving and would require a saving effort that is highly unrealistic. For instance, financing a constant 4 percent growth rate of gross domestic product per capita with no improvement in total factor productivity would require a national saving rate of around 50 percent in the first decade and 80 percent in 25 years. However, if productivity rises, sustaining and improving high rates of economic growth becomes viable. Following the previous example...

Measuring Pro-Poor Growth

Ravallion, Martin; Chen, Shaohua
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
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55.96%
It is important to know how aggregate economic growth or contraction was distributed according to initial levels of living. In particular, to what extent can it be said that growth was "pro-poor?" There are problems with past methods of addressing this question, notably that the measures used are inconsistent with the properties that are considered desirable for a measure of the level of poverty. The authors provide some new tools for assessing to what extent the aggregate growth process in an economy is pro-poor. The key measurement tools is the "growth incidence curve," which gives growth rates by quantiles (such as percentiles) ranked by income. Taking the area under this curve up to the headcount index of poverty gives a measure of the rate of pro-poor growth consistent with the Watts index for the level of poverty. The authors give examples using survey data for China during the 1990s. Over 1990-99, the ordinary growth rate of household income per capita in China was 7 percent a year. The growth rate by quantile varied from 3 percent for the poorest percentile to 11 percent for the richest...

Saving and Growth in Sri Lanka

Hevia, Constantino; Loayza, Norman
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
55.98%
In the aftermath of its long-standing civil war, Sri Lanka is keen to reap the social and economic benefits of peace. Even in the middle of civil conflict, the country was able to grow at rates that surpassed those of its neighbors and most developing countries. It is argued, then, that the peace dividend may bring about even higher rates of economic growth. Is this possible? And if so, under what conditions? To be sure, Sri Lanka's high growth rate in the past three decades did not come for free. It took an increasing effort of resource mobilization in the country, with a rise in national saving from 15 percent of gross domestic product in the mid-1970s to 25 percent in 2010. This rise in national saving was fundamentally fueled and sustained by the private sector. In the future, however, the private saving rate is likely to decline because the demographic transition experienced in the country is bound to produce higher old dependency rates in the next two decades. However, the public sector has much room for reducing its deficits and increasing public investment. Similarly...

Reflexo da taxa de crescimento e do peso corporal em leitoas sobre o desempenho reprodutivo e longevidade da matriz; Influence of gilt growth rate and body weight on reproductive performance and sow longevity

Amaral Filha, Wald'ma Sobrinho
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
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65.96%
As leitoas são consideradas a categoria de matrizes que deve ter uma atenção especial na preparação para a vida produtiva, pois a introdução no momento certo no rebanho de produção é crucial para o desempenho e longevidade desta futura matriz. Todo período experimental deste trabalho foi realizado em uma granja produtora de leitões, localizada no Centro-Oeste do país, com capacidade de alojar 2400 fêmeas (Camborough 22®). O primeiro estudo teve como objetivo determinar se leitoas com maiores taxas de crescimento, em diferentes categorias de idade no início do estímulo à puberdade, apresentam o primeiro estro em idade mais precoce. As leitoas foram avaliadas de acordo com dois grupos de idade à exposição ao cachaço (A= 130-149 d, n= 751 e B= 150-170 d, n= 735) e de acordo com três classes de taxa de crescimento (TC) do nascimento ao início do estímulo (I = 550-649 g/d, n= 371; II= 650-725 g/d, n= 749 e III= 726- 830 g/d, n= 366). A idade no momento da exposição ao cachaço para as leitoas dos Grupos A e B foram 142,6 ± 4,9 e 157,0 ± 5,1 dias, respectivamente. No geral, em 40 dias de estimulação, 85% das leitoas foram púberes. No grupo A, leitoas da classe TCIII manifestaram maior percentual cumulativo de fêmeas em estro dentro de 10 dias (38...

Effect of starvation on growth rate, muscle growth and energy density of puyen, Galaxias maculatus

Boy, Claudia Clementina; Vanella, Fabián Alberto; Lattuca, María Eugenia; Ceballos, Santiago Guillermo; Aureliano, Daniel; Rimbau, Sonia; Gutiérrez, M.; Fernandez, Daniel Alfredo
Fonte: Wiley Blackwell Publishing, Inc Publicador: Wiley Blackwell Publishing, Inc
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
65.89%
Seasonal growth of G. maculatus in Tierra del Fuego, at the southern limit of its distribution, would be explained by the variation of extrinsic factors, and experiments of fasting under summer conditions would allow researchers to potentially focus on feeding/fasting conditions independent of other seasonal cues, and thus discriminate the effect of fasting from other winter factors that influence fish growth. The current study presents information about muscle growth of Galaxias maculatus and the results of an experiment evaluating the effect of fasting on growth rate, total muscle growth and energy density in this species, under summer-like conditions. Uniform pattern of muscle fibers suggest the absence of mosaic hyperplastic growth in G. maculatus. Hyperplasic growth was over before puyen reached 65 mm total length, and hyperplasia cessation was correlated to the transition from juvenile to adult stage. In the experimental animals, where hypertrophic growth was the unique process responsible for adult muscle growth, fasting decreased mass, condition and energy density of experimental individuals, and stopped the hypertrophic growth. These results proof that reduced food consumption in southerly puyen populations during winter might contribute to the seasonality of growth previously reported for this species. A provisional summer growth rate of 2?3 mm/month is suggested for populations inhabiting the southern limits of this species? distribution. We propose G. maculatus as a useful model species to study hypertrophic muscle growth.; Fil: Boy...

Calculating effective growth rate from a random Leslie model: Application to incidental mortality analysis

Caceres Garcia Faure, Manuel Osvaldo; Cáceres Saez, Iris
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
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Demographic models are commonly used to study cetacean population dynamics and are characterized by a wide range of age classes. The primary building blocks are age-specific survival or mortality and birth rates, which can be combined using a Leslie matrix protocol to provide estimates of maximum possible rates of increase for population size. In this context, specific mortality data are valuable for modeling the viability of threatened species. Depletion of prey, pollution, and other anthropogenic disturbances are believed to have contributed to the decline of populations, but the evidence is less conclusive for these factors than for bycatch. In an attempt to estimate a population growth rate that incorporates uncertainties in vital parameters, we apply a random Leslie analysis to calculate effective growth rate for the time-dependent mean-value population. Here we provide the algorithm to implement it for a general 13×13 random survival model. An effective growth rate can be characterized by studying the time evolution of the mean-value population vector state (in an age-structured description). We show that the asymptotic behavior of the mean-value vector state, which characterizes the population growth rate when the model has random vital parameters...

The impact of disease on the survival and population growth rate of the Tasmanian devil

Lachish, Shelly; Jones, Menna E; McCallum, Hamish
Fonte: British Ecological Society Publicador: British Ecological Society
Tipo: Artigo de Revista Científica
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65.8%
1. We investigated the impact of a recently emerged disease, Devil Facial Tumour Disease (DFTD), on the survival and population growth rate of a population of Tasmanian devils, Sarcophilus harrisii, on the Freycinet Peninsula in eastern Tasmania. 2. Corma

Testing the Growth Rate vs. Geochemical Hypothesis for latitudinal variation in plant nutrients

Lovelock, Catherine; Feller, Ilka C; Ball, Marilyn; Ellis, J; Sorrell, B
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.77%
Two hypotheses have been proposed to explain increases in plant nitrogen (N) and phosphorus (P) concentrations with latitude: (i) geochemical limitation to P availability in the tropics and (ii) temperature driven variation in growth rate, where greater g

Relative contributions of leaf area ratio and net assimilation rate to change in growth rate depend on growth temperature: comparative analysis of subantarctic and alpine grasses

Medek, Danielle; Ball, Marilyn; Schortemeyer, Marcus
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.87%
• The present study shows that the relative contributions of leaf area ratio (LAR) and net assimilation rate (NAR) to variation among species in relative growth rate (RGR) depend on growth temperature. • We grew three subantarctic and three alpine Poa

Efecto del tipo de cereal (cebada vs maíz) sobre la ingestión, la ganancia de peso y las características de la canal de corderos alimentados con pienso y paja o sólo con pienso; Effect of cereal type (barley vs maize) on feed intake, growth rate and carcass characteristics of lambs fed mixed or all-concentrate diets

Landa, Roberto; Mantecón, Ángel R.; Frutos, Pilar; Rodríguez, Ana Belén; Giráldez, Francisco Javier
Fonte: Asociación Interprofesional para el Desarrollo Agrario Publicador: Asociación Interprofesional para el Desarrollo Agrario
Tipo: Artículo Formato: 8046499 bytes; application/pdf
SPA
Relevância na Pesquisa
65.8%
13 páginas, 3 figuras, 5 tablas.; [ES] Se utilizaron 32 corderos recién destetados de raza Merina para estudiar e1 efecto de dos tipos de pienso, elaborados con cereales sin procesar (Pienso C: 75% cebada, 20% torta de soja, 2% melazas y 3% vitaminas y minerales; Pienso M: 75% maíz, 20% torta de soja,2% melazas y 3% vitaminas y minerales), y de la suplementación con paja de cereal sobre la ingestión, la ganancia diaria de peso y las características de la canal (peso, morfología, pérdidas por oreo y pH de la canal, rendimiento comercial y color de la carne y de la grasa). El efecto de la interacción entre los factores estudiados y de la suplementación con paja no fue en ningún caso estadísticamente significativo (P > 0,05). Tampoco el tipo de cereal empleado en los piensos afectó significativamente (P > 0,05) a los parámetros analizados, con excepción (P < 0,05) del peso de la canal caliente, el rendimiento comercial y el índice de compacidad de la canal. Los mayores valores correspondieron a los corderos que consumieron el pienso M (peso de la canal caliente: 12,4 vs 12,6 kg; rendimiento comercial: 46,2 vs 47,6%; índice de compacidad: 252 vs 262 g/cm) y fueron, probablemente, consecuencia de un mayor engrasamiento de la canal causado por la diferente relación proteína/energía de los piensos utilizados. Los resultados obtenidos sugieren que no es necesario administrar paja a los corderos cuando se administra el cereal en grano. Ahora bien...

Water relations and leaf growth rate of three agropyron genotypes under water stress

García,María G.; Busso,Carlos A.; Polci,Pablo; García Girou,Norberto L.; Echenique,Vivivan
Fonte: Biocell Publicador: Biocell
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2002 EN
Relevância na Pesquisa
65.79%
The effects of water stress on leaf water relations and growth are reported for three perennial tussock grass genotypes under glasshouse conditions. Studies were performed in genotypes El Palmar INTA and Selección Anguil of Agropyron scabrifolium (Döell) Parodi, and El Vizcachero of A. elongatum (Host) Beauv. Agropyron scabrifolium El Palmar INTA is native to a region with warm-temperate and humid climate without a dry season, and an average annual precipitation of 900 mm. Agropyron scabrifolium Selección Anguil comes from a region with a sub-humid, dry to semiarid climate and a mean annual precipitation of 600 mm. Agropyron elongatum is a widespread forage in semiarid Argentina with well-known water stress resistance. A mild water stress treatment was imposed slowly; plants reached a minimum pre-dawn leaf water potential of about -1.83 MPa by day 21 after watering was withheld. In all genotypes, water stress led to a reduction of leaf growth. There was a tendency for a greater epicuticular wax accumulation on water-stressed plants of A. scabrifolium Selección Anguil and A. elongatum than on those of A. scabrifolium El Palmar INTA. This may have contributed to obtain greater turgor pressures and relative water contents in the first two than in the later genotype. In turn...

Effect of the dose of oral Hydrocortisone on growth rate during long-term treatment of children with salt losing congenital adrenal hyperplasia

Ciaccio,M.; Montiveros,C.; Rivarola,M. A.; Belgorosky,A.
Fonte: Medicina (Buenos Aires) Publicador: Medicina (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2002 EN
Relevância na Pesquisa
65.87%
The effect of the dose of oral hydrocortisone on stature growth rate of patients with the salt losing form of congenital adrenal hyperplasia and adequate electrolyte balance was here assessed. Thirty patients (21 girls and 9 boys) were followed longitudinally for 0.52 to 8.64 years, between chronological ages 0.35 and 8.64 years. Nine consecutive periods (Ps) of follow up were defined in order to compare two auxological parameters, height (H) at the end of a follow up P and DH standard deviation score (SDS). According to growth rate during a particular P, two types of Ps were defined: Ps with DH SDS > -0.5 (Group 1, satisfactory growth rate) and Ps with DH SDS = or < -0.5 (Group 2, poor growth rate). A cut off value of 18.5 mg/m²/day of oral hydrocortisone (95% CI upper limit of group 1) was defined to separate acceptable from excessive doses. In P2, mean (± SD) H SDS (-1.81 ± 1.15) was significantly lower than in any of the other Ps (p < 0.001). In P1 and in P2, DH SDS was negative, but it was positive in P3 and in P4. Hydrocortisone dose in P1 and in P2 was significantly higher than in the rest of the Ps. All patients in P1 and most patients in P2 , but not in other Ps, received excessive doses. Predicted adult H, calculated in 9 patients was not statistically different from their respective target H. It is concluded that...

Morphometric parameters, zeta potential and growth rate of Lactobacillus casei Shirota by effect of different bile salts

González-Vázquez,R.; Gutiérrez-López,G.F.; Arellano-Cárdenas,S.; López-Villegas,E. O.; Téllez-Medina,D. I.; Rivera-Espinoza,Y.
Fonte: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería Publicador: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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65.82%
Effects of primary and secondary bile salts, conjugated to glycine [glycocholic (GCA) and glycodeoxycholic acid (GDCA)], taurine [taurocholic acid (TCA), taurodeoxycholic acid (TDCA)] on morphometry and growth rate of Lactobacillus casei Shirota were studied. Images obtained by scanning electron microscopy showed modification (p < 0.05) in cell minor axis and aspect ratio. The former was modified by GCA while the second by all the bile salts used. The growth rate (µ) values were: 1.95, 0.66, 0.32, 1.89 and 1.86 h−1 in MRS medium without salts and with GCA, GDCA, TCA and TDCA, respectively. Estimated doubling time was: 0.35, 0.36 and 0.37 h for MRS medium without salts, and with TCA and TDCA, respectively. For GCA and GDCA, a decrease in growth was observed from 4 h and 2 h of incubation, respectively. Bile salt hydrolase activity was determined qualitatively and quantitatively. L. casei Shirota showed activity on taurine-conjugated bile salts. The zeta potential was determined by using the same conditions as those for quantification of bile salt hydrolase activity and different potentials for each dispersion system were found; the zeta potential values were related to the metabolism of L. casei Shirota.