Estrogen receptor concentration and social factors as predictors of natural killer cell activity in early-stage breast cancer patients. Confirmation of a model

Previous work of ours has demonstrated that a significant amount of natural killer (NK) activity variance after surgery in stage I and II breast cancer patients could be accounted for by both the estrogen receptor (ER) status of the tumor and by social factors, namely, perceived social support and seeking social support as a general coping strategy. As considerable evidence has accumulated that social support in both animal and human populations may have survival value, we sought to test the reliability of this regression model, using coping and perceived support factor values obtained at 3 months after surgery to account for concurrent follow-up NK activity in this serially assessed group of patients. It was found that the most significant variable predicting NK activity at follow-up was tumor ER concentration, with higher NK activity associated with ER- status. In addition, seeking social support as a coping strategy, as well as the perceived quality of support, also entered the model to account for a significant amount of NK activity variance (multivariate F = 5.25, p less than 0.001). If, as the literature suggests, NK activity is relevant to breast cancer control, and since ER- tumors have a worse prognosis, we suggest here that perhaps such tumors are resistant to control by NK cells because they lack the ability to attract an accumulation of effector cells to the tumor site, or because blocking factors at the site of the tumor prevent local tumor control at the site of action. The finding related to social support also replicates results from an independent sample of breast cancer patients. This finding, taken together with other evidence that this social variable is associated with longer survival in breast cancer populations, underscores the potential importance of this social support variable. Our findings also suggest one possible immunological variable involved, with potential clinical significance, for this patient population.     

Influential Factors of Insufficient Physical Activity among Adolescents with Asthma in Taiwan

Purpose

Little research has been reported concerning insufficient physical activity in Taiwanese adolescents with asthma. The aims of this paper are to compare the amount of physical activity between asthmatic and non-asthmatic adolescents in Taiwan, as well as to investigate the influential factors associated with insufficient physical activity in asthmatic adolescents.

Methods

Self-reporting structured questionnaires (socio-economic status, scale of family support for physical activity, amount of physical activity) and peak expiratory flow were assessed from 286 adolescents with asthma and 588 non-asthmatic adolescents in a cross-sectional design. Insufficient amount of physical activity was based on less than 300 minutes per week of moderate and vigorous physical activity.

Results

Adolescents with asthma have a greater amount of physical activity and a higher level of family support than those who are non-asthmatic. In Taiwan, adolescents with asthma, girls relative to boys, obesity relative to average weight, and low family support relative to high family support were found to be associated with insufficient physical activity.

Conclusion

Physical activity in adolescents with asthma is insufficient especially in girls, in asthmatics with obesity, and in those with low family support. We suggest that physical activity programs should be applied to Taiwan adolescents with asthma in order to match the criteria of 300 minutes per week of moderate and vigorous physical activity, especially for girls, the obese and those with a low level of family support.     

Optimizing Immobilization and Stabilization of Feruloyl Esterase from Humicola Insolens and its Application for the Feruloylation of Oligosaccharides

Feruloyl esterase (FAE)-catalyzed esterification reaction is as a potential route for the biosynthesis of feruloylated oligosaccharides as functional ingredients. Immobilization of FAE from Humicola insolens on metal chelate-epoxy supports was investigated. The study of effects of immobilization parameters using response surface methodology revealed the significance of enzyme/support ratio (3.25-29.25 mg/g support), immobilization time (14-38 h), buffer molarity (0.27-1.25 M) and pH (4.0-8.0). The interactions between enzyme-to-support ratio/buffer molarity and enzyme-to-support ratio/pH were found to be critical for the modulation of the immobilization activity yield and the retention of specific activity, respectively. Optimum conditions for FAE-immobilization on metal chelate Sepabeads® EC-EP R were identified to be 22.75 mg FAE/g support, pH of 5.0, 27.7 h and buffer molarity of 0.86 M. At these conditions, an activity yield of 82.4%, a specific activity retention of 143.4%, and an enzyme activity of 395.4 μmol/min. g support were achieved. Further incubation of the immobilized FAE at pH 10.0 improved its thermostability. Increasing the pore size of the epoxy support improved the retention of FAE hydrolytic activity and the esterifying efficiency of the immobilized biocatalyst. Optimally immobilized and stabilized FAE on metal chelate-epoxy support retained up to 92.9% of the free enzyme feruloylation efficiency to xylooligosaccharides..     

Overweight Children's Barriers to and Support for Physical Activity

Objective: As the epidemic of overweight increases among youth, research needs to examine factors that may influence children's participation in weight‐related health behaviors. This study examined overweight children's perceived barriers to and support for physical activity compared with nonoverweight children. Research Methods and Procedures: Barriers to and support for physical activity were examined among 84 overweight children attending a summer fitness camp or a university‐based weight loss clinic. Barriers and support levels were then compared with those of 80 nonoverweight children of a similar age range. Results: Body‐related barriers were the most predominant barrier type among overweight youth, especially among overweight girls. Overweight children, particularly girls, reported significantly higher body‐related, resource, and social barriers to physical activity compared with nonoverweight children and lower levels of adult support for physical activity. Discussion: Overweight children may be particularly vulnerable to body‐related barriers to physical activity, and reducing such barriers may serve as physical activity intervention points most relevant for overweight youth. Future interventions may also benefit from enhancing support for physical activity from adults and peers.     

Immobilization of perfluoroalkylated enzymes in a biologically active state onto Perflex support.

Perflex has been introduced by E. I. du Pont de Nemours and Co., Inc., as a new fluorocarbon-based technology for protein immobilization. Due to the hydrophobic character of the support, however, significant loss of enzymatic activity may occur upon immobilization of certain enzymes, which appears to be due to a large conformational change of the protein ("inversion"). Pretreatment of the Perflex support with a neutral fluorosurfactant lessened the surface hydrophobicity, thus decreasing the hydrophobic interaction between the support and the protein. Modification of enzymes with a high number of fluorocarbon residues, which forms a hydrophobic "envelope" around the protein, also appears to prevent enzyme inactivation upon immobilization on Perflex support. Moreover, preactivation of the support with either perfluorooctylpropylisocyanate or reactive poly(fluoroalkyl) sugar reagents greatly improves the enzyme particle activity by increasing the amount of immobilized enzyme. Fluorosurfactant treatment of the support activated with perfluorooctylpropylisocyanate improves the retention of activity for sensitive enzymes such as alpha-chymotrypsin and increases the wetability and ease of handling of the Perflex particles.     

Adsorption of enzymes on krill chitin modified with carbon disulfide

Krill chitin modified with carbon disulfide was used as a support of enzymes. The dithiocarbamino groups created after reaction of CS(2) with chitinous NH(2) can participate in binding the enzymes without denaturation and loss in activity. The stability of these bonds depends on pH and decreases gradually at ionic strengths higher than 0.01. Chitin modified with CS(2) can be used as a support for enzymes having high activity at mild conditions of pH and ionic strength.     

Advantages of the pre-immobilization of enzymes on porous supports for their entrapment in sol-gels

In this work, we have compared the entrapment of free or previously immobilized glucose oxidase using a sol-gel technique. The preimmobilization was carried out on Sepabeads (a porous support) derivatized with glutaraldehyde as the functional group. The prior immobilization of the enzyme permitted to maintain the enzyme activity intact after the formation of the sol-gel. In fact, only 10% of the enzyme activity was lost whereas the soluble enzyme lost 60% of its initial activity. Additionally, enzyme leakage from the sol-gel matrix was avoided, which was relatively high when entrapping the soluble enzyme (39% of the enzyme activity was released after 16 h of incubation in a buffered solution). Moreover, the immobilized enzyme, inside the porous support, cannot be in contact with the sol-gel, and, therefore, it maintained the stability achieved by means of the multipoint covalent attachment on the Sepabeads support.     

The phospholipid headgroup specificity of an ATP-dependent calcium pump.

We have replaced the lipid associated with a purified calcium transport protein with a series of defined synthetic dioleoyl phospholipids in order to determine the effect of phospholipid headgroup structure on the ATPase activity of the protein. At 37 degrees C the zwitterionic phospholipids (dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine) support the highest activity, while a phospholipid with two negative charges (dioleoyl phosphatidic acid) supports an activity which is at least twenty times lower. Dioleoyl phospholipids with a single net negative charge support at intermediate ATPase activity which is not affected by the precise chemical structure of the phospholipid headgroup. The protocol used to determine the phospholipid headgroup specificity of calcium transport protein is novel because it establishes the composition of the lipid in contact with the protein without the need to isolate defined lipid-protein complexes. This allows the lipid specificity to be determined using only very small quantities of test lipids. We also determined the ability of the same phospholipids to support calcium accumulation in reconstituted membranes. Two requirements had to be met. The phospholipid had to support the ATPase activity of the pump protein and it had to form sealed vesicles as determined by electron microscopy. Since a number of phospholipids met those requirements it is clear that in vitro the lipid specificity of the calcium-accumulating system is rather broad.     

The phospholipid headgroup specificity of an atp-dependent calcium pump

We have replaced the lipid associated with a purified calcium transport protein with a series of defined synthetic dioleoyl phospholipids in order to determine the effect of phospholipid headgroup structure on the ATPase activity of the protein. At 37°C the zwitterionic phospholipids (dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine) support the highest activity, while a phospholipid with two negative charges (dioleoyl phosphatidic acid) supports an activity which is at least twenty times lower. Dioleoyl phospholipids with a single net negative charge support at intermediate ATPase activity which is not affected by the precise chemical structure of the phospholipid headgroup. The protocol used to determine the phospholipid headgroup specificity of calcium transport protein is novel because it establishes the composition of the lipid in contact with the protein without the need to isolate defined lipid-protein complexes. This allows the lipid specificity to be determined using only very small quantities of test lipids.We also determined the ability of the same phospholipids to support calcium accumulation in reconstituted membranes. Two requirements had to be met. The phospholipid had to support the ATPase activity of the pump protein and it had to form sealed vesicles as determined by electron microscopy. Since a number of phospholipids met those requirements it is clear that in vitro the lipid specificity of the calcium-accumulating system is rather broad.     

Differential effects of temperature on a membrane adenosine triphosphatase and associated phosphatase.

Arrhenius plots of a membrane (Na+ + K+)-dependent ATPase (adenosine triphosphatase) activity showed characteristic discontinuities, whereas those of the associated K+-dependent phosphatase activity did not. These findings support the contention that the phosphatase activity does not depend on phospholipid in the same way as does the ATPase activity.     

On the importance of the support material for enzymatic synthesis in organic media. Support effects at controlled water activity

Enzymes were deposited on different porous support materials and these preparations were used to catalyze reactions in organic media. Reactions were carried out at specific water activities, achieved by equilibrating both the enzyme preparation and the substrate solution at the desired water activity before mixing them and thereby starting the reactions. The reaction rates obtained at the same water activity with different supports differed greatly, indicating a direct influence of the support on the enzyme. For horse liver alcohol dehydrogenase, Celite was the best support, and the reaction rate increased with increasing water activity. In the alpha-chymotrypsin-catalyzed alcoholysis of N-acetyl-L-phenylalanine ethyl ester with 1-butanol, high rates were again obtained with Celite, but with this support only about one third of the ethyl ester was converted to butyl ester, the rest was hydrolyzed. With the polyamide support, Accurel PA6, alcoholysis was the dominating reaction, and by using a low water activity (0.33), hydrolysis was completely suppressed while still maintaining a high alcoholysis activity. Controlled pore glass (CPG), derivatized with either hexyl or glucosyl groups, had quite different properties as enzyme supports. For horse liver alcohol dehydrogenase, glucose-CPG was a much better support than hexyl-CPG, and in the alpha-chymotrypsin-catalyzed reactions, glucose-CPG favored hydrolysis, and hexyl-CPG alcoholysis, at water activities exceeding 0.8. The results are discussed considering the absorption of water on the enzymes, on the supports and the solubility of water in the reaction media; all these parameters were measured separately.     

Utilization of powdered pig bone as a support for immobilization of lipase

Pig bone was examined for its suitability as a support material for lipase immobilization. It was observed that pig bone (PB) particles dispersed readily in both polar and nonpolar solvents, and lipase was easily adsorbed. In particular lipase adsorbed on olive oil-soaked pig bone (OPB) particles exhibited a higher hydrolytic activity than that in lipase adsorbed on a selection of other representative supports, regardless of removing the presoaked olive oil from the particles after immobilization of lipase. The optimum pH and temperature for hydrolytic activity of OPB-adsorbed lipase were the same as those for free lipase, although thermal resistance was increased by immobilization. When OPB-adsorbed lipase was used for repeated batch reactions of olive oil hydrolysis, an activity of more than 80% of the initial activity of each run could he retained after 46 h reaction. The results suggest that PB is an excellent support material.     

双醛淀粉柔性固定木瓜蛋白酶研究

提出“柔性固定化酶”的模型,即：用一亲水、柔性高分子链接枝于载体表面制得柔性固定化载体,再用其以共价键合的方式进行酶的柔性固定化。其特点是：柔性固定可改善因直接固定化及手臂固定化使酶失活的缺陷,并提高固定化酶的自由度;如选用粒径单分散微球可改善固定化反应及固定化酶催化反应的均一性。以双醛淀粉(DAS)为柔性链对羧基化聚苯乙烯载体进行柔性化修饰后,固定木瓜蛋白酶,其活力回收率可达50％．相当于用戊二醛进行手臂固定化的活力回收率的2倍。     

Supportive or information-processing functions of the mature protoplasmic astrocyte in the mammalian CNS? A critical appraisal

It has been proposed that astrocytes should no longer be viewed purely as support cells for neurons, such as providing a constant environment and metabolic substrates, but that they should also be viewed as being involved in affecting synaptic activity in an active way and, therefore, an integral part of the information-processing properties of the brain. This essay discusses the possible differences between a support and an instructive role, and concludes that any distinction has to be blurred. In view of this, and a brief overview of the nature of the data, the new evidence seems insufficient to conclude that the physiological roles of mature astrocytes go beyond a general support role. I propose a model of mature protoplasmic astrocyte function that is drawn from the most recent data on their structure, the domain concept and their syncytial characteristics, of an independent rather than integrative functioning of the ends of each process where the activities that affect synaptic activity and blood vessel diameter will be concentrated.     

Leaf size modifies support biomass distribution among stems, petioles and mid-ribs in temperate plants

The implications of extensive variation in leaf size for biomass distribution between physiological and support tissues and for overall leaf physiological activity are poorly understood. Here, we tested the hypotheses that increases in leaf size result in enhanced whole-plant support investments, especially in compound-leaved species, and that accumulation of support tissues reduces average leaf nitrogen (N) content per unit dry mass (N(M)), a proxy for photosynthetic capacity. Leaf biomass partitioning among the lamina, mid-rib and petiole, and whole-plant investments in leaf support (within-leaf and stem) were studied in 33 simple-leaved and 11 compound-leaved species. Support investments in mid-ribs and petioles increased with leaf size similarly in simple leaves and leaflets of compound leaves, but the overall support mass fraction within leaves was larger in compound-leaved species as a result of prominent rachises. Within-leaf and within-plant support mass investments were negatively correlated. Therefore, the total plant support fraction was independent of leaf size and lamina dissection. Because of the lower N(M) of support biomass, the difference in N(M) between the entire leaf and the photosynthetic lamina increased with leaf size. We conclude that whole-plant support costs are weakly size-dependent, but accumulation of support structures within the leaf decreases whole-leaf average N(M), potentially reducing the integrated photosynthetic activity of larger leaves.     

Immobilization of lipases for non-aqueous synthesis

Immobilization of lipases involves many levels of complications relating to the structure of the active site and its interactions with the immobilization support. Interaction of the so called hydrophobic ‘lid’ with the support has been reported to affect synthetic activity of an immobilized lipase. In this work we evaluate and compare the synthetic activity of lipases from different sources immobilized on different kinds of supports with varying hydrophobicity. Humicola lanuginosa lipase, Candida antarctica lipase B and Rhizomucor miehei lipase were physically adsorbed onto two types of hydrophobic carriers, namely hydrophilic carriers with conjugated hydrophobic ligands, and supports with base matrix hydrophobicity. The prepared immobilized enzymes were used for acylation of n-butanol with oleic acid as acyl donor in iso-octane with variable water content (0–2.8%, v/v) as reaction medium. Enzyme activity and effect of water on the activity of the immobilized derivatives were compared with those of respective soluble lipases and a commercial immobilized lipase Novozyme 435. Both R. miehei and H. lanuginosa immobilized lipases showed maximum activity at 1.39% (v/v) added water concentration. Sepabeads, a methacrylate based hydrophilic support with conjugated octadecyl chain showed highest immobilized esterification (synthetic) activity for all three enzymes, and of the three R. miehei lipase displayed maximum esterification activity comparable to the commercial enzyme.     

Activation of an S6 kinase from rat astroglial cells by cAMP

Forskolin and isoproterenol, agonists of adenylate cyclase activity, and dibutyryl cyclic AMP, stimulated an S6 kinase activity in astroglial cells. This activity was insensitive to the thermostable inhibitor of cyclic AMP-dependent protein kinase and had the same behaviour on a DEAE-Sephacel column as the mitogen stimulated S6 kinase. These observations support the idea that the cyclic AMP cascade, as well as various growth factors, can activate S6 kinase.     

The use of gas-phase substrates to study enzyme catalysis at low hydration

Although there are varying estimates as to the degree of enzyme hydration required for activity, a threshold value of ca. 0.2 g of water per gram of protein has been widely accepted. The evidence upon which this is based is reviewed here. In particular, results from the use of gas-phase substrates are discussed. Results using solid-phase enzyme-substrate mixtures are not altogether in accord with those obtained using gas-phase substrates. The use of gaseous substrates and products provides an experimental system in which the hydration of the enzyme can be easily controlled, but which is not limited by diffusion. All the results show that increasing hydration enhances activity. The results using gas-phase substrates do not support the existence of a critical hydration value below which enzymatic activity is absent, and suggest that enzyme activity is possible at much lower hydrations than previously thought; they do not support the notion that significant hydration of the surface polar groups is required for activity. However, the marked improvement of activity as hydration is increased suggests that water does play a role, perhaps in optimizing the structure or facilitating the flexibility required for maximal activity.     

Immobilization of lipases and assay in continuous fixed bed reactor

Lipases are versatile enzymes regarding the range of reactions they catalyse and substrates on which they act. They are as well important as catalyst in organic synthesis. Their immobilization on appropriate supports confer them greater stability besides the possibility of operating in continuous reactors. In order to explore these abilities, the reactions involving hydrolysis of p-nitrophenyl acetate (PNPA) and transesterification of PNPA with n-butanol were chosen. Lipases from two different sources were assayed, namely: microbial (Candida rugosa, CRL, Sigma Type VII) and pancreatic (PPL, Sigma, Type II). Two immobilization methods were also used, namely: 1). adsorption, using as support the following silica derivatives (150-300 microm e 450micro): phenyl, epoxy, amino and without derivation, and 2). covalent binding, using glutaraldehyde as binding agent and silica amino as support. This later method led to better results. Hydrolytic activity was 6.1 U/g(support) for CRL and 0.97 U/g(support) for PPL, and of transesterification, 2,8 U/g(support) for CRL and 1,9 U/g(support) for PPL. Stability of the immobilized enzyme as a function of temperature was evaluated for CRL at 40 degrees C and 50 degrees C and for PPL at 32 degrees C and 40 degrees C. The assays were initially carried out batchwise, both for soluble and immobilized enzymes, aiming to the obtention of parameters for the continuous reactor. Lipases immobilized by covalent binding were used in the assays of operational stability in continuous reactors. For PPL in aqueous medium, at 32 degrees C, and CRL in organic medium at 40 degrees C, both operating continuously, no significant loss of activity was detected along the analysis period of 17 days. In the case of CRL in aqueous medium at 40 degrees C there was a loss of activity around 40% after 18 days. For PPL in organic medium at 40 degrees C the loss was 33% after 20 days. Comparing both sources with each other, very different results were obtained. Higher activity was found for CRL, both for hydrolysis and for transesterification reactions, with higher stability in organic medium. PPL showed lower activity as well as higher stability in aqueous medium. The immobilization method by covalent binding showed to be the most appropriate. Immobilized lipases are therefore relatively stable both in aqueous and organic medium.     

Enhancing performance of lipase immobilized on methyl-modified silica aerogels at the adsorption and catalysis processes: Effect of cosolvents

Hydrophobic silica aerogels modified with methyl group were applied as support to immobilize Candida rugosa lipase (CRL). At the adsorption process, different alcohols were used to intensify the immobilization of CRL. The results showed that n-butanol wetting the hydrophobic support prior to contacting with enzyme solution could promote lipase activity, but the adsorption quantity onto the support decreased. Based on this, a novel immobilization method was proposed: the support contacted with enzyme solution without any alcohols, and then the immobilized enzymes were activated by 90% (V) n-butanol solution. The experimental results showed that this method could keep high adsorption quantity (413.0 mg protein/g support) and increase the lipase specific activity by more than 50%. To improve the stability of immobilized lipase, the support after adsorption was contacted with n-octane to form an oil layer covering the immobilized lipases, thus the leakage can be decreased from over 30–4% within 24 h. By utilizing proper cosolvents, a high enzyme activity and loading capacity as well as little loss of lipase was achieved without covalent linkage between the lipase and the support. This is known to be an excellent result for immobilization achieved by physical adsorption only.