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Growth Curves (growth + curve)
Terms modified by Growth Curves Selected AbstractsVarying Coefficient Model with Unknown Within-Subject Covariance for Analysis of Tumor Growth CurvesBIOMETRICS, Issue 4 2008Robert T. Krafty Summary In this article we develop a nonparametric estimation procedure for the varying coefficient model when the within-subject covariance is unknown. Extending the idea of iterative reweighted least squares to the functional setting, we iterate between estimating the coefficients conditional on the covariance and estimating the functional covariance conditional on the coefficients. Smoothing splines for correlated errors are used to estimate the functional coefficients with smoothing parameters selected via the generalized maximum likelihood. The covariance is nonparametrically estimated using a penalized estimator with smoothing parameters chosen via a Kullback,Leibler criterion. Empirical properties of the proposed method are demonstrated in simulations and the method is applied to the data collected from an ovarian tumor study in mice to analyze the effects of different chemotherapy treatments on the volumes of two classes of tumors. [source] Molt and growth of an estuarine crab, Chasmagnathus granulatus (Brachyura: Varunidae), in Mar Chiquita coastal lagoon, ArgentinaJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2004T. A. Luppi Summary Juvenile and adult growth of Chasmagnathus granulatus was studied in the laboratory in terms of molt increment in size (MI) and the intermolt period (IP), comparing data obtained from short-term (STE) and long-term (LTE) laboratory experiments. Crabs in a pre-molt condition were collected for STE, including the entire size range of the species. Larger crabs remained in the laboratory no more than 14 days; the average time to molt was 5.8 ± 3.1 days. We registered the molt of 94 females, 64 males and 34 undifferentiated juveniles and calculated their MI. Moreover, 24 males and four females were reared in the laboratory over 3 years (LTE). Hiatt diagrams did not show sex-specific differences between juveniles of both sexes, but revealed differences between juveniles and adults in each sex as well as between adults of both sexes. The MI decreased gradually with size; this pattern was described with a quadratic model. The IP increased exponentially with size. The presence of regenerating limbs diminished the MI. The abdomen of females reached its final shape and maximum relative width at functional maturity. Growth curves for both sexes were calculated using the von Bertalanffy model, but this model yielded an underestimation of the actual maximum size of this crab. [source] Modelling and predicting the effect of temperature, water activity and pH on growth of Streptococcus iniae in TilapiaJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008K. Zhou Abstract Aims:, To evaluate and model the growth of Streptococcus iniae affect by temperatures (10,45°C), water activity (Aw; 0·995,0·957), and pH (5,8). Methods and Results:, Temperatures, Aw, and pH were adjusted. The behaviour of S. iniae was studied and modelled. Growth curves were fitted by using logistic, Gompertz, and Baranyi models. The maximum growth rates obtained from the primary model were then modelled as a function of temperature, Aw, and pH using the Belehradek-type models for secondary model. The optimum values for growth were found to be in the range of 35,40°C, Aw 0.995,1, and pH 6,7. The statistical characteristics of the models were validated by r2, mean square error, bias, and accuracy factors. The results of validation indicated that Baranyi model performed the best. Conclusions:, The effect of temperature, Aw/NaCl, pH control of S. iniae in tilapia could be satisfactorily predicted under current experimental conditions, and the proposed models could serve as a tool for this purpose. Significance and Impact of the Study:, The suggested predictive model can be used for risk assessment concerning S. iniae in tilapia. [source] Ectoines as compatible solutes and carbon and energy sources for the halophilic bacterium Chromohalobacter salexigensJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006C. Vargas Abstract Aims:, To investigate the catabolism of ectoine and hydroxyectoine, which are the major compatible solutes synthesized by Chromohalobacter salexigens. Methods and Results:, Growth curves performed in M63 minimal medium with low (0·75 mol l,1 NaCl), optimal (1·5 mol l,1 NaCl) or high (2·5 mol l,1 NaCl) salinity revealed that betaine and ectoines were used as substrate for growth at optimal and high salt. Ectoine transport was maximal at optimal salinity, and showed 3- and 1·5-fold lower values at low and high salinity respectively. The salt-sensitive ectA mutant CHR62 showed an ectoine transport rate 6·8-fold higher than that of the wild type. Incubation of C. salexigens in a mixture of glucose and ectoine resulted in a biphasic growth pattern. However, CO2 production due to ectoine catabolism was lower, but not completely abolished, in the presence of glucose. When used as the sole carbon source, glycine betaine effectively inhibited ectoine and hydroxyectoine synthesis at any salinity. Conclusions:, The catabolic pathways for ectoine and hydroxyectoine in C. salexigens operate at optimal and high (although less efficiently) salinity. Endogenous ectoine(s) may repress its own transport. Ectoine utilization was only partially repressed by glucose. Betaine, when used as carbon source, suppresses synthesis of ectoines even under high osmolarity conditions. Significance and Impact of the Study:, This study is a previous step to the subsequent isolation and manipulation of the catabolic genes, so as to generate strains with enhanced production of ectoine and hydroxyectoine. [source] Retinoic acid induces expression of the interleukin-1, gene in cultured normal human mammary epithelial cells and in human breast carcinoma linesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2002Limin Liu Retinoic acid (RA) and its derivatives inhibit the proliferation of normal human mammary epithelial cells (HMEC) and some breast carcinoma lines by mechanisms which are not fully understood. To identify genes that mediate RA-induced cell growth arrest, an HMEC cDNA library was synthesized and subtractive screening was performed. We identified the interleukin-1, (IL-1,) gene as an RA induced gene in HMEC. Northern blot analyses showed that the IL-1, gene was up-regulated as early as 2 h after RA treatment. Results from the treatment of HMEC with cycloheximide and actinomycin D indicated that the regulation of the IL-1, gene by RA occurred at the transcriptional level and that the IL-1, gene is a direct, downstream target gene of RA. To evaluate the effects of IL-1, on cell proliferation, the proliferation of HMEC was measured in the presence of RA or IL-1,, or both. Either RA or IL-1, could significantly inhibit the proliferation of HMEC. However, the addition of soluble IL-1 receptor antagonist (sIL-1ra) to the cell culture medium did not block RA-induced HMEC growth inhibition, whereas sIL-1ra did block the growth inhibition of HMEC by IL-1,. IL-1, expression was not observed in the three carcinoma cell lines, MCF-7, MDA-MB-231, and MDA-MB-468, as compared to the HMEC. Growth curves of the breast carcinoma cell lines showed strong inhibitory effects of RA and IL-1, on the growth of the estrogen receptor (ER) positive MCF-7 cell line, but only a small effect on the ER negative MDA-MB-231 cells. The expression of the IL-1, gene was also transcriptionally activated by RA in normal epithelial cells of prostate and oral cavity. Our results suggest that: (a) the IL-1, gene is a primary target of RA receptors in HMEC; (b) the enhanced expression of the IL-1, gene does not mediate the RA-induced growth arrest of HMEC; and (c) the expression of the IL-1, gene is low or absent in all three human breast carcinoma cell lines examined, but the defect in the IL-1, signaling pathway may be different in ER positive versus ER negative carcinoma cells. © 2002 Wiley-Liss, Inc. [source] VARIATION OF LAG TIME AND SPECIFIC GROWTH RATE AMONG 11 STRAINS OF SALMONELLA INOCULATED ONTO STERILE GROUND CHICKEN BREAST BURGERS AND INCUBATED AT 25C,JOURNAL OF FOOD SAFETY, Issue 4 2000THOMAS P. OSCAR ABSTRACT One strain of 11 serotypes or 11 strains of Salmonella, which were isolated from the ceca of broilers, were surveyed for their growth kinetics on sterile ground chicken breast burgers incubated at 25C to determine the variation of lag time and specific growth rate. Growth curves, four per strain, were fit to a two-phase linear model to determine lag time (h) and specific growth rate (log10/h). Repeatability of growth kinetics measurements for individual strains had a mean coefficient of variation of 11.7% for lag time (range: 5.8 to 17.3%) and a mean coefficient of variation of 6.7% for specific growth rate (range: 2.7 to 13.3%). Lag time among strains ranged from 2.2 to 3.1 h with a mean of 2.8 h for all strains, whereas specific growth rate among strains ranged from 0.3 to 0.38 log10 per h with a mean of 0.35 log10per h for all strains. One-way analysis of variance indicated that lag time (P =0.029) and specific growth rate (P =0.025) differed slightly among strains. S. Haardt had a shorter (P < 0.05) lag time than S. Agona and S. Brandenburg, whereas the specific growth rate of S. Enteritidis was less than (P < 0.05) the specific growth rates of S. Typhimurium and S. Brandenburg. All other strains had similar lag times and specific growth rates. The coefficient of variation among strains was 9.4% for lag time and 5.7% for specific growth rate. These results indicate that there were only minor differences in the lag times and specific growth rates among the strains of Salmonella surveyed. Thus, the growth kinetic values obtained with one strain of Salmonella may be useful for predicting the growth of other strains of Salmonella for which data do not currently exist. [source] Peptone preparation from fishing by-productsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2005Gustavo HF Vieira Abstract Panulirus argus and P laevicauda lobster carapace meat, lobster tail parings, whole shrimp tails from Cinnamon shrimp, (Macrobachium amazonicum) and scraps left over from filleting Piaui croaker (Plagioscion squamosissimus) were separated, hydrolysed and then lyophilised and used as individual sources of peptone in media for the cultivation of Escherichia coli. The composition of the test media was: 0.3% meat extract, 0.5% peptone and 0.1% lactose. These new sources of peptone were compared with commercially obtained peptone (OXOID), commonly used in laboratory media, and which served as the control. E coli growth curves for each source of peptone were evaluated using the turbidimetry method and biomass quantification was determined by the dry curve method in order to obtain the respective growth rates for these media. E coli grew faster and for longer using alternative sources of peptone than with the control. The peptone yield from lobster carapace meat was 17.6%, from lobster tail parings 10.2%, from Piaui croaker fish scraps 23% and from whole Ciannamon shrimp tails 12.9%. Growth curves and the biomass figures indicate the feasibility of using these fishery by-products as raw materials for peptone production for microbial media. Copyright © 2005 Society of Chemical Industry [source] Force impairment in calpain 3,deficient mice is not correlated with mechanical disruptionMUSCLE AND NERVE, Issue 5 2003Françoise Fougerousse MD Abstract Defects in human calpain 3 are responsible for limb-girdle muscular dystrophy type 2A, an autosomal-recessive disorder characterized mainly by late-onset proximal muscular atrophy. A corresponding murine model has previously been generated by gene targeting. In this report, muscular activity of calpain 3,deficient (capn3,/,) mice was evaluated at different ages. Growth curves showed a progressive global muscular atrophy. Histological examination throughout the lifespan of mice confirmed the dystrophic lesions. Whole animal tests showed only a mild significant impairment of the forelimbs. Studies of the mechanical properties of selected isolated fast- and slow-twitch muscles demonstrated that slow-twitch muscles were significantly weaker in capn3,/, mice than in wild-type mice. Three different tests showed that there was no membrane disruption, suggesting a nonmechanical etiology of capn3,/, mice dystrophy. These findings are consistent with a mechanism involving signaling systems. Muscle Nerve 27: 616,623, 2003 [source] Temperature constraints on the growth and functioning of root organ cultures with arbuscular mycorrhizal fungiNEW PHYTOLOGIST, Issue 1 2005Mayra E. Gavito Summary ,,In this study we investigated the effects of temperature on fungal growth and tested whether the differences in fungal growth were related to the effects of temperature on carbon movement to, or within, the fungus. ,,Growth curves and C uptake-transfer-translocation measurements were obtained for three arbuscular mycorrhizal fungi (AMF) isolates cultured within a 6,30°C temperature range. A series of experiments with a model fungal isolate, Glomus intraradices, was used to examine the effects of temperature on lipid body and 33P movement, and to investigate the role of acclimation and incubation time. ,,Temperature effects on AMF growth were both direct and indirect because, despite clear independent root and AMF growth responses in some cases, the uptake and translocation of 13C was also affected within the temperature range tested. Root C uptake and, to a lesser extent, C translocation in the fungus, were reduced by low temperatures (< 18°C). Uptake and translocation of 33P by fungal hyphae were, by contrast, similar between 10 and 25°C. ,,We conclude that temperature, between 6 and 18°C, reduces AMF growth, and that C movement to the fungus is involved in this response. [source] Analysis of facial growth in subjects with syndromic ectodermal dysplasia: a longitudinal analysisORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2 2002N Bondarets Structured Abstract Authors, Bondarets N, Jones RM, McDonald F. Objective, To examine the craniofacial growth pattern of patients diagnosed with syndromic ectodermal dysplasia. >Design, Mixed longitudinal analysis of lateral cephalograms. Setting, The data were analysed using a multilevel modelling technique with the MLwiN application software and the results presented numerically and graphically. Sample Population, All 61 subjects had severe hypodontia with the number of absent teeth (excluding third molars) ranging from 6 to 28 (mean=15.4). At presentation the subjects had a mean age of 133 months and were followed longitudinally for between one and five subsequent occasions (mean 2.66 occasions; mean age at completion of observation 207 months). Outcome Measures, Lateral cephalograms taken at each visit. Experimental Variables, Analysis of four angular measurements and four linear measurements, together with one calculated ratio. Results, Growth curves are presented showing the trends of craniofacial growth. Conclusions, The most significant findings were for a universal tendency for the individuals to undergo a change in sagittal relationship of the jaws, becoming markedly more Class III with time. We have also demonstrated a significant difference in growth between the anterior and posterior face heights indicating that the subjects have a tendency to an anterior growth rotation. [source] Growth curves of pediatric patients with biliary atresia following living donor liver transplantation: Factors that influence post-transplantation growthPEDIATRIC TRANSPLANTATION, Issue 7 2007Takeshi Saito Abstract:, We evaluated the growth curves of children with BA after LDLT, and identified factors influencing growth velocity one-yr after LDLT (,Z). The clinical data of 51 children with BA, who had an LDLT at our center from 2001 to 2005, were retrospectively reviewed. The Z scores for height and weight, and ,Z were studied. The correlation between ,Z and various clinical factors was evaluated statistically. Multivariate stepwise analyses were performed for ,Z. The average height and weight Z scores at the time of LDLT were ,1.34 ± 1.36 (±s.d.) and ,0.78 ± 1.15, respectively. Among 30 BA recipients with stable liver function after transplant, weight returned to normal one-yr post-transplantation. However, height did not return to normal even by the third post-transplantation year. On multivariate analyses, 73% of the variance in height ,Z could be accounted for by factors such as standardized height at the time of LDLT (proportion of variance: 38%), number of steroid pulse treatments (17%), donor age (10%), and the presence of HVS (9%). Fifty-four percentage of the variance in weight ,Z could be accounted for by factors such as standardized weight at the time of LDLT (37%) and the total steroid dose given (17%). Height and weight status at the time of LDLT likely have the strongest impact on ,Z. Additional factors include steroid exposure, age of the living donor, and presence of HVS, all of which should be considered to improve post-transplantation growth. [source] Aging Adversely Impacts Biological Properties of Human Bone Marrow-derived Mesenchymal Stem Cells: Implications for Tissue Engineering Heart Valve ConstructionARTIFICIAL ORGANS, Issue 3 2010Yuan Xin Abstract Our aim was to study the aging effects on the in vitro biological properties of bone marrow-derived mesenchymal stem cells (BMSCs) for construction of tissue-engineered heart valves. BMSCs were taken from teenagers with congenital heart diseases, and middle-aged and elderly patients with valvular diseases. Proliferative abilities were compared among the three groups by using colony-forming unit counting and growth curves (5-bromo-2,-deoxyuridine assay). Cell differentiation, vascular endothelial growth factor (VEGF) release under hypoxic condition, and migratory abilities were compared as well. Colony-forming units in the teenage group were significantly greater than those in the other two groups (P < 0.05), and significantly higher counts were observed in the middle age group than in the aged group (P < 0.05). Growth curves presented similar trends in which cells' proliferative abilities in the aged group decreased significantly (P < 0.05), while no differences were noted between the two nonaged groups. The differentiation potential to endothelial cells, osteoblasts and adipocytes, VEGF releases, and migratory abilities differed significantly between the aged group and nonaged groups (P < 0.05). However, no differences were noted between the two nonaged groups. BMSCs from older patients with heart valve diseases could be harvested and expanded successfully, and the phenotype and morphology were uniform as nonaged groups. However, the proliferative and differentiation properties of aged cells, as well as cytokine release and migratory abilities, are significantly impaired. [source] The upper arm muscle and fat area of Santal children: an evaluation of nutritional statusACTA PAEDIATRICA, Issue 1 2009Sutanu Dutta Chowdhury Abstract Aims: The purpose of this study is to determine the growth pattern of upper arm muscle area (UAMA), upper arm fat area (UAFA) and upper arm muscle area by height (UAMAH) and assessment of magnitude of undernutrition on the basis of these parameters in Santal children. Methods: UAMA and UAFA of 890 (473 boys and 417 girls) Santal children aged 5,12 years were calculated from mid-upper arm circumference and triceps skinfold. Results: Growth curves of UAFA-for-age and UAMA by height in Santal boys and girls are placed at lower level of reference curve indicating severe undernutrition. The growth curves of UAMA-for-age in Santal children of both sexes do not indicate severe undermutrition. 17.13% Santal boys and 20.63% girls were truly undernourished on the basis of three Z-scores of height-for-age, weight-for-height and UAMAH of each subject. Santal children have more UAMA and less UAFA compared to similar undernourished children of Sugalis. Conclusion: Growth curves of UAFA-for-age and UAMA by height are good indicators of nutritional status in Santal children. UAMA and UAFA may not be similarly affected in undernourished children of every community. A comprehensive approach to identify the truly undernourished child has been suggested from this study. [source] Kinetic studies on the influence of temperature and growth rate history on crystal growthCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008P. M. Martins Abstract Crystallization experiments of sucrose were performed in a batch crystallizer to study the effect of temperature and growth rate history on the crystal growth kinetics. In one of the growth methods adopted, the isothermal volumetric growth rate (RV) is determined as a function of supersaturation (S) at 35, 40 and 45 ºC. In the other, crystals are allowed to grow at constant supersaturation by automatically controlling the solution temperature as the solute concentration decreased. Using the latter method RV is calculated as the solution is cooled. The obtained results are interpreted using empirical, engineering and fundamental perspectives of crystal growth. Firstly, the overall activation energy (EA) is determined from the empirical growth constants obtained in the isothermal method. The concept of falsified kinetics, widely used in chemical reaction engineering, is then extended to the crystal growth of sucrose in order to estimate the true activation energy (ET) from the diffusion-affected constant, EA. The differences found in the isothermal and constant supersaturation methods are explained from the viewpoint of the spiral nucleation mechanism, taking into account different crystal surface properties caused by the growth rate history in each method. Finally, the crystal growth curve obtained in the batch crystallizer at 40 ºC is compared with the one obtained in a fluidized bed crystallizer at the same temperature. Apparently divergent results are explained by the effects of crystal size, hydrodynamic conditions and growth rate history on the crystallization kinetics of sucrose. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A regional frequency analysis of United Kingdom extreme rainfall from 1961 to 2000INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2003H. J. Fowler Abstract Multi-day rainfall events are an important cause of recent severe flooding in the UK, and any change in the magnitude of such events may have severe impacts upon urban structures such as dams, urban drainage systems and flood defences and cause failures to occur. Regional pooling of 1-, 2-, 5- and 10-day annual maxima for 1961 to 2000 from 204 sites across the UK is used in a standard regional frequency analysis to produce generalized extreme value growth curves for long return-period rainfall events for each of nine defined climatological regions. Temporal changes in 1-, 2-, 5- and 10-day annual maxima are examined with L-moments using both a 10 year moving window and the fixed decades of 1961,70, 1971,80, 1981,90 and 1991,2000. A bootstrap technique is then used to assess uncertainty in the fitted decadal growth curves and to identify significant trends in both distribution parameters and quantile estimates. There has been a two-part change in extreme rainfall event occurrence across the UK from 1961 to 2000. Little change is observed at 1 and 2 days duration, but significant decadal-level changes are seen in 5- and 10-day events in many regions. In the south of the UK, growth curves have flattened and 5- and 10-day annual maxima have decreased during the 1990s. However, in the north, the 10-day growth curve has steepened and annual maxima have risen during the 1990s. This is particularly evident in Scotland. The 50 year event in Scotland during 1961,90 has become an 8-year, 11-year and 25-year event in the East, South and North Scotland pooling regions respectively during the 1990s. In northern England the average recurrence interval has also halved. This may have severe implications for design and planning practices in flood control. Copyright © 2003 Royal Meteorological Society [source] Assessing the longitudinal course of depression and economic integration of south-east Asian refugees: an application of latent growth curve analysisINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 4 2002K.A.S. Wickrama Abstract This paper has both methodological and substantive application for mental-health researchers. Methodologically, it presents the latent growth curve (LGC) technique within a structural equation modelling (SEM) framework as a powerful tool to analyse change in depressive symptoms and potential correlates of such changes. The rationale for LGC analysis and subsequent elaboration of this statistical approach are presented. The limitations of traditional analytical methods are also addressed. Substantively, the paper considers socio-contextual factors as correlates of change in symptoms, and examines the dynamic systematic relationship with the degree of economic integration of south-east Asian immigrants in Canada over time. Using the LGC technique, this study also investigated how the longitudinal course of sub-clinical depression places individuals at risk for developing full-blown major depression. The LGC results provided strong evidence for the reciprocal influence between economic integration and subclinical depression of immigrants. The initial level of economic integration negatively influenced the rate of change in subclinical depression whereas the initial level of sub-clinical depression negatively influenced the rate of change in economic integration. Both initial level and the rate of change in subclinical depression placed individuals at risk for full-blown major depression. However, traditional auto-regressive models were not capable of revealing these dynamic associations. Thus, an investigation of within-individual change in symptoms and potential correlates of such changes is necessary to understand the process that results in full-blown mental disorder. Copyright © 2002 Whurr Publishers Ltd. [source] Use of serial pig body weights for genetic evaluation of daily gainJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010B. Zumbach Summary This study examined the utility of serial weights from FIRE (Feed Intake Recording Equipment, Osborne Industries, Inc., Osborne, KS, USA) stations for an analysis of daily gain. Data included 884 132 body weight records from 3888 purebred Duroc pigs. Pigs entered the feeder station at age 77,149 days and left at age 95,184 days. A substantial number of records were abnormal, showing body weight close to 0 or up to twice the average weight. Plots of body weights for some animals indicated two parallel growth curves. Initial editing used a robust regression, which was a two-step procedure. In the first step, a quadratic growth curve was estimated assuming small or 0 weights for points far away from the curve; the process is iterative. In the second step, weights more than 1.5 SD from the estimated growth curve were treated as outliers. The retained body weight records (607 597) were averaged to create average daily weight (170 443) and then used to calculate daily gains (152 636). Additional editing steps included retaining only animals with ,50 body weight records and SD of the daily gain ,2 kg, followed by removing records outside 3 SD from the mean for given age, across all the animals , the resulting data set included 69 068 records of daily gain from 1921 animals. Daily gain based on daily, weekly and bi-weekly intervals was analysed using repeatability models. Heritability estimates were 0.04, 6 and 9%, respectively. The last two estimates correspond to heritability of 28% for a 12 week interval. For daily gain averaged weekly, the estimate of heritability obtained with a random regression model varied from 0.07 to 0.10. After extensive editing, body weight records from automatic feeding stations are useful for genetic analyses of daily gain from weekly or bi-weekly but not daily intervals. [source] Quantitative relation between shear history and rheological properties of LDPEADVANCES IN POLYMER TECHNOLOGY, Issue 4 2001Masayuki Yamaguchi The role of the applied processing equipment shear history on the rheological properties of low-density polyethylene was studied in detail. It was found that the shear history depresses the melt strength and the oscillatory shear modulus, especially the storage modulus in low frequency region. This phenomenon is not caused by lowering of the molecular weight, which remained the same as the original, for all shear history samples, indicating absence of mechanical/thermal degradation during processing. Furthermore, annealing the melt processed samples enhances both the melt strength and the oscillatory modulus to the values of the original, unsheared sample. Finally we applied shear history in a cone-and-plate rheometer and found that the growth curve of the storage modulus, which can be expressed by a simple equation, is determined by both the duration of the flow and the magnitude of the applied shear stress. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 261,269, 2001 [source] Telomerase upregulation is a postcrisis event during senescence bypass and immortalization of two Nijmegen breakage syndrome T cell culturesAGING CELL, Issue 2 2010Sofie Degerman Summary Our knowledge on immortalization and telomere biology is mainly based on genetically manipulated cells analyzed before and many population doublings post growth crisis. The general view is that growth crisis is telomere length (TL) dependent and that escape from crisis is coupled to increased expression of the telomerase reverse transcriptase (hTERT) gene, telomerase activity upregulation and TL stabilization. Here we have analyzed the process of spontaneous immortalization of human T cells, regarding pathways involved in senescence and telomerase regulation. Two Nijmegen breakage syndrome (NBS) T cell cultures (S3R and S4) showed gradual telomere attrition until a period of growth crisis followed by the outgrowth of immortalized cells. Whole genome expression analysis indicated differences between pre-, early post- and late postcrisis cells. Early postcrisis cells demonstrated a logarithmic growth curve, very short telomeres and, notably, no increase in hTERT or telomerase activity despite downregulation of several negative hTERT regulators (e.g. FOS, JUN D, SMAD3, RUNX2, TNF-, and TGF,-R2). Thereafter, cMYC mRNA increased in parallel with increased hTERT expression, telomerase activity and elongation of short telomeres, indicating a step-wise activation of hTERT transcription involving reduction of negative regulators followed by activation of positive regulator(s). Gene expression analysis indicated that cells escaped growth crisis by deregulated DNA damage response and senescence controlling genes, including downregulation of ATM, CDKN1B (p27), CDKN2D (p19) and ASF1A and upregulation of CDK4, TWIST1, TP73L (p63) and SYK. Telomerase upregulation was thus found to be uncoupled to escape of growth crisis but rather a later event in the immortalization process of NBS T cell cultures. [source] GROWTH KINETICS OF CLOSTRIDIUM PERFRINGENS IN COOKED BEEF,JOURNAL OF FOOD SAFETY, Issue 2 2003LIHAN HUANG ABSTRACT The objective of this work was to investigate the growth kinetics of a three-strain cocktail of Clostridium perfringens in cooked beef. The study was conducted by growing the heat-activated spores in ground beef under isothermal conditions between 17,50C. A four-parameter Gompertz equation was used as a primary model to fit the growth curves along with a modified Ratkowsky model to analyze the temperature dependence of the bacterial growth. Results indicated that the Gompertz model could accurately describe the growth of C. perfringens in cooked beef. The estimated theoretical minimum, optimum, and maximum growth temperatures of this organism in cooked beef were 9.8, 47.1, and 50.8C, respectively. A linear relationship between the durations of the lag and exponential phases of growth curves was observed in this study. Such a linear relationship can be used to generate a linear isothermal growth curve complete with the lag, exponential, and stationary phases without complex mathematical computation. The kinetic models and growth parameters obtained from this study potentially can be applied to the food industry to design appropriate cooling schedules and estimate the growth of C. perfringens in thermally processed beef products under temperature abuse conditions. [source] Prenatal diagnosis and postnatal follow-up of a child with mosaic trisomy 22 with several levels of mosaicism in different tissuesJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2010Vincenzo Mazza Abstract We report on the case of a patient with mosaic trisomy 22, who was diagnosed prenatally by amniocentesis during the 16th week of pregnancy. In the foetus, three trisomic clones were found out of the nine that were analyzed (the other six clones had a 46,XY karyotype). Cytogenetic analysis of cord blood during the 20th week of pregnancy showed a normal male karyotype; however, a placental biopsy that was performed at the same time showed 100% and 95% trisomic cells in the chromosomal analysis of direct and long-term cultures, respectively. A follow-up ultrasonographic examination excluded major congenital malformations and the abdominal and cranial circumferences were normal until the 24th week of pregnancy. At this point, a deflection of the growth curve occurred and the values were persistently below the 3rd centile until birth. After birth, karyotypic and fluorescent in situ hybridisation analyses performed on the fibroblasts of the neonate showed that 3,4% of the cell lines were trisomic, and studies using microsatellite markers showed normal allelic segregation, which excluded uniparental disomy. The period of postnatal follow-up was characterised by a significant growth deficit (height and head circumference were less than the 3rd centile) and by mental retardation. The present case is compatible with other earlier reports that showed that the levels of trisomy 22 are tissue-specific and are of little help in establishing the prognosis of the chromosomal abnormality. [source] Variety-specific Epidemiology of Cercospora beticola Sacc. and Consequences for Threshold-based Timing of Fungicide Application in Sugar BeetJOURNAL OF PHYTOPATHOLOGY, Issue 4 2010Ulrike Kaiser Abstract In Central Europe, fungicides to control leaf spot disease in sugar beet caused by Cercospora beticola are applied based on thresholds of disease incidence (DI, per cent of infected plants). As variety-specific fungicide application was not analyzed to date, the epidemiology of C. beticola and its effect on white sugar yield (WSY) in varieties with different susceptibility were investigated at seven sites in Germany and Austria in 2004 and 2005. All varieties reached the summary thresholds 5 / 15 / 45% DI in all environments. Fitting a logistic growth curve to DI revealed significant differences among varieties. At high disease pressure, susceptible varieties reached a considerably higher disease severity (DS, per cent of infected leaf area) at harvest and a larger area under disease progress curve (AUDPC) than resistant varieties. Fitting a logistic growth curve to DS showed an increasing differentiation among varieties with time. The growth rate estimated based on the logistic growth curve was the only variable that performed equally well in differentiating varieties under low and high disease pressure. With increasing disease pressure, varieties differed considerably in WSY, but differences between susceptible and resistant varieties were significant only in some environments. The disease-loss relation between AUDPC and relative WSY was variety-specific. Resistant varieties had an approximately identical WSY with and without infection and compensated for negative infection effects even at higher AUDPC. Therefore, at high disease pressure, resistant varieties had a higher relative yield compared to susceptible ones. However, our results indicate that there is no need to develop variety-specific thresholds, but resistant varieties reach the established thresholds later than susceptible ones. Consequently, the time of fungicide application can be delayed in resistant varieties. This will help to reduce the use of fungicides to the bare essentials as requested for the integrated crop protection management. [source] Rhizocarpon calibration curve for the Aoraki/Mount Cook area of New Zealand,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2005Thomas V. Lowell Abstract Development of Rhizocarpon growth curve from the Aoraki/Mount Cook area of New Zealand provides a means to assess Little Ice Age glacier behaviour and suggests approaches that have wider application. Employing a sampling strategy based on large populations affords the opportunity to assess which of various metrics (e.g. single largest, average of five largest, mean of an entire population) best characterise Rhizocarpon growth patterns. The 98% quantile from each population fitted with a quadric curve forms a reliable representation of the growth pattern. Since this metric does not depend on the original sample size, comparisons are valid where sample strategy must be adapted to local situations or where the original sample size differs. For the Aoraki/Mount Cook area a surface 100 years old will have a 98% quantile lichen diameter of 34.3,mm, whereas a 200-year-old surface will have a lichen diameter of 73.7,mm. In the Southern Alps, constraints from the age range of calibration points, the flattening of the quadric calibration curve and ecological factors limit the useful age range to approximately 250 years. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fetal growth and neonatal mortality in KoreaPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 5 2007Jae S. Hong Summary The fetal growth curve and neonatal mortality rate, based on gestational age and birthweight, are important for identifying groups of high-risk neonates and developing appropriate medical services and health-care programmes. The purpose of this study was to develop a national fetal growth curve for neonates in Korea, and examine the Korean national references for fetal growth and death according to their characteristics. Data of Korean vital statistics linked National Infant Mortality Survey conducted on births in 1999 were used in this study. The total livebirths were 621 764 in 1999, which were grouped into singletons (n = 609 643) and twins (n = 9805) for analysis. Birthweight/gestational age-specific fetal growth curves and neonatal mortality rates were based on 250 g of birthweight and weekly gestational age intervals for each characteristic of the birth. The features of high-risk neonates such as small-for-gestational-age and the limit of viability in Korea were different from those of Western countries. Difference in fetal growth and death was also detected in other characteristics of the fetus (gender and plurality of birth) besides race. The fetal growth curve of males was higher than that of females, and was higher in singleton than in twins. The neonatal mortality rate was higher in males (singleton, 2.6; twin, 23.5) than females (singleton, 2.1; twin, 15.9), and higher in twins (19.8/1000) than in singletons (2.4/1000). However, in neonates with gestational age >29 weeks and birthweight >1000 g, the neonatal mortality rate was lower in twins than in singletons. The limit of viability was gestational age 27 weeks and birthweight 1000 g, which was similar in singletons and twins regardless of gender. To improve the health of neonates in a country, it is imperative to investigate the characteristics of fetal growth and death under the particular circumstances of the country. When risk is defined for neonates account must be taken of differences in race, gender and plurality of birth, as the neonatal mortality rate varies depending on those factors. [source] Effect of Boron Neutron Capture Therapy for Melanotic and Amelanotic Melanoma Transplanted into Mouse BrainPIGMENT CELL & MELANOMA RESEARCH, Issue 1 2002Masaki Iwakura In order to develop a protocol to treat brain metastatic melanoma using our 10B- p -boronophenylalanine (BPA) boron neutron capture therapy (BNCT), we initiated the following studies (i), Comparative analyses of boron biodistribution between melanoma proliferating in the brain and skin among melanotic and amelanotic types, and (ii) Therapeutic evaluation of BPA,BNCT for brain melanoma models of both types, using survival times. Our present data have revealed that boron concentration in melanoma proliferating in the brain, the major prerequisite for successful BNCT, showed a positive correlation to melanin synthesizing activity in the same way as melanoma proliferating in skin. Further, the boron concentration ratio of melanoma to normal surrounding tissue for brain melanoma models was considerably higher than that for subcutaneous (s.c.) ones because of the existence of the blood,brain barrier (BBB). Additionally, from analyses of median and mean survival times following BNCT using low, middle, and high neutron doses, the therapeutic effect of BNCT for the amelanotic A1059 melanoma appeared at first glance to be higher than that for the highly BPA attracting and highly relative biological effect equivalent dose obtaining B15b melanoma. As the survival time was dependent on both regression and regrowth curves, and because the brain melanoma model in small animals made it difficult to evaluate these curves separately, we further examined the in vivo growth curve of both types of melanomas following implantation in s.c. tissue. The melanotic B15b melanoma was indeed found to possess much higher growth rate as compared with that of the amelanotic A1059 melanoma. The significance of boron biodistribution studies and BNCT survival curve analyses in forming an effective clinical protocol for individual human cases of melanoma brain metastasis is discussed. [source] Early vocabulary development in deaf native signers: a British Sign Language adaptation of the communicative development inventoriesTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 3 2010Tyron Woolfe Background:, There is a dearth of assessments of sign language development in young deaf children. This study gathered age-related scores from a sample of deaf native signing children using an adapted version of the MacArthur-Bates CDI (Fenson et al., 1994). Method:, Parental reports on children's receptive and expressive signing were collected longitudinally on 29 deaf native British Sign Language (BSL) users, aged 8,36 months, yielding 146 datasets. Results:, A smooth upward growth curve was obtained for early vocabulary development and percentile scores were derived. In the main, receptive scores were in advance of expressive scores. No gender bias was observed. Correlational analysis identified factors associated with vocabulary development, including parental education and mothers' training in BSL. Individual children's profiles showed a range of development and some evidence of a growth spurt. Clinical and research issues relating to the measure are discussed. Conclusions:, The study has developed a valid, reliable measure of vocabulary development in BSL. Further research is needed to investigate the relationship between vocabulary acquisition in native and non-native signers. [source] Anatomy and physiology of the gastro-intestinal tract and growth curves of the ostrich (Struthio camelus)ANIMAL SCIENCE JOURNAL, Issue 6 2004Ross G. COOPER ABSTRACT The ostrich is an important animal in many livestock industries and in the developing world. The digestive system of the ostrich differs considerably from that of non-ruminant animals or poultry. The genetic potential of an ostrich can be described by its characteristic growth curve. This present paper presents an account of the rearing, anatomy of the gastro-intestinal tract, and growth curves of this bird. [source] Determination of diauxic lag in continuous cultureBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2008Dong-Uk Lee Abstract A procedure was developed to characterize diauxic lag of bacteria switching between electron acceptors in continuous culture. In this procedure, a virtual batch growth curve is developed by integrating the time-dependent net specific growth rates of bacteria observed under continuous flow conditions. The length of diauxic lag and the highest net specific growth rate following lag are conveniently estimated from the virtual batch curve. The procedure was found to give reproducible diauxic lag lengths and highest net specific growth rates when applied to experimental data from replicate continuous culture trials. Biotechnol. Bioeng. 2008;101: 642,646. © 2008 Wiley Periodicals, Inc. [source] Virus-like particle production at low multiplicities of infection with the baculovirus insect cell systemBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003Luis Maranga Abstract The baculovirus insect cell expression system (BEVS) was used for the production of self-forming Porcine parvovirus -like particles (VLPs) in serum-free medium. A low multiplicity of infection (MOI) strategy was used to overcome an extra virus amplification step, undesirable in industrial production, and to minimize the virus passage effect. It was confirmed that the time of infection (TOI) and MOI are dependent variables. Higher cell densities were obtained at low MOIs, keeping a constant TOI; however, both volumetric and specific productivities were lower. In synchronous infection, at high MOI, the specific productivity decreased when the cells were infected in the late phase of growth. Product degradation due to cell lysis strongly influenced the optimal time of harvest (TOH). Time of harvest was found to be highly dependent on the MOI, and a direct relationship with the cell yield was obtained. Analysis of the culture medium reveals that glutamine depletion occurs in the late phase of the growth. Supplementation of glutamine to uninfected cell cultures resulted in an increased cell yield. Its addition to cultures infected in the middle phase of the growth curve was also able to restore the productivity levels, but addition to cells in their stationary phase caused no observable effect on product expression. The study clearly shows that for a specific TOI it is not obvious what the correct MOI should be to obtain the best volumetric productivity. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 245,253, 2003. [source] Cross-sectional analysis of the association between age and corpus callosum size in chimpanzees (Pan troglodytes)DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2010William D. Hopkins Abstract The CC is the major white matter tract connecting the cerebral hemispheres and provides for interhemispheric integration of sensory, motor and higher-order cognitive information. The midsagittal area of the CC has been frequently used as a marker of brain development in humans. We report the first investigation into the development of the corpus callosum and its regional subdivisions in chimpanzees (Pan troglodytes). Magnetic resonance images were collected from 104 chimpanzees (female n,=,63, male n,=,41) ranging in age from 6 years (pre-pubescent period) to 54 years (old age). Sustained linear growth was observed in the area of the CC subdivision of the genu; areas of the posterior midbody and anterior midbody displayed nonlinear growth during development. After adjusting for total brain size, we observed linear growth trajectories of the total CC and CC subdivisions of the genu, posterior midbody, isthmus and splenium, and nonlinear growth trajectories of the rostral body and anterior midbody. These developmental patterns are similar to the development of the CC in humans. As the growth curves of the CC mirrors growth seen in the percentage of white matter in humans, our results suggest chimpanzees show continued white matter development in regions related to cognitive development. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52:133,141, 2010 [source] | |||||||||||||||||||||||||||||||||||||||||||