Hydrophobicity, amphilicity, and flexibility: Relation between molecular protein properties and the macroscopic effects of surface activity.

Their surface activity enables proteins to form and stabilize foam, which can be used for in situ product separation or foam fractionation. Thus, it would be highly desirable to predict the surface activity of proteins based on their molecular properties like hydrophobicity, amphilicity, or structure on primary, secondary, and tertiary level. Ionic strength and pH were adjusted to gain maximum surface activity. The surface activity decreased in the order α lactalbumin > ß­lactoglobulin > trypsinogen > papain. For the theoretical analysis, the database was extended by including 2 hydrophobins into the investigation, since they are known to exhibit an outstanding surface activity. No relation to the macroscopic behavior was found considering the hydrophobicity. I.e., the non-hydrophobins did not differ significantly from each other, and from the hydrophobins, one was significantly hydrophobic, and the other was significantly hydrophilic. Also, no relations were found considering the amphilicity of the secondary structure elements. However, taking into account the tertiary protein structure, it was found that for most of the proteins investigated, the presence of non-buried amphiphilic secondary structure elements in combination with a certain amount of flexibility correlates with the surface activity.

Contribution of Secondary Structure Changes to the Surface Activity of Proteins.

A major difference between proteins and surfactants is that proteins are capable of changing their structure during refolding processes in the adsorbed state. It is often reported that these interfacial structure changes increase the surface activity of proteins. In order to investigate this, the surface activity of 5 proteins was determined in foam fractionation experiments, where pH and ionic strength were adjusted separately to gain the maximum surface activity for each protein. Infrared Reflection Absorption Spectroscopy was performed for each protein to analyze the changes in secondary structure after adsorption. In order to investigate quick structural changes, transmission Fourier Transform Infrared spectroscopy was performed to gain information about the secondary structure of the dissolved, non-adsorbed proteins. It was found that most proteins maintain a native-like conformation when adsorbed at the interface. With increasing time, most of the proteins investigated increased the amount of ß-sheets at the interface. This slow process went along with a slow increase in surface pressure. A correlation between structural changes on molecular level and surface activity on macroscopic level could not be found. However, the absolute increase of surface pressure at the very beginning of the adsorption process correlated with the surface activity of the proteins, suggesting that the slow processes on molecular level do not have a considerable impact on macroscopic surface activity.

Influence of thermally induced structure changes in diluted ß-lactoglobulin solutions on their surface activity and behavior in foam fractionation.

Surface activity is an intrinsic protein feature, leading to the capability of aqueous protein solutions to form foam. This feature provides opportunities for downstream processing, such as usage of foam fractionation for purification. In order to investigate the impact of the surface activity on the performance of the foam fractionation process, protein solutions with different surface activity were produced by different thermal denaturation of aqueous ß-lactoglobulin solutions. The effectiveness of the denaturation procedure was verified with circular dichroic spectroscopy, and the impact on surface activity was determined via dynamic surface tension measurement. The increased surface activity resulted in higher foamate flow rates. Furthermore, the effects could be correlated with secondary structure changes and with the dynamic surface pressure. The new result of this study is that the effect of the denaturation of a protein on foam fractionation depends on the protein concentration. At the lower feed concentration, effects became visible, which could not be observed at the higher concentration.

Exploiting intrinsic triangular geometry in relativistic (3)He+Au collisions to disentangle medium properties.

Recent results in d+Au and p+Pb collisions at RHIC and the LHC provide evidence for collective expansion and flow of the created medium. We propose a control set of experiments to directly compare particle emission patterns from p+Pb, d+Au, and ^{3}He+Au or t+Au collisions at the same sqrt[s_{NN}] . Using a Monte Carlo Glauber simulation we find that a ^{3}He or triton projectile, with a realistic wave function description, induces a significant intrinsic triangular shape to the initial medium. If the system lives long enough, this survives into a significant third-order flow moment v_{3} even with viscous damping. By comparing systems with one, two, and three initial hot spots, one could disentangle the effects from the initial spatial distribution of the deposited energy and viscous damping. These are key tools for answering the question of how small a droplet of matter is necessary to form a quark-gluon plasma described by nearly inviscid hydrodynamics.

Prenatal counseling beyond the threshold of viability.

OBJECTIVE: It is common clinical practice to counsel parents expecting an early-moderate premature birth. The aim of the current study was to assess maternal knowledge of potential problems of prematurity after counseling. STUDY DESIGN: Prospective study of 49 participants admitted between 23 and 33 weeks gestation with threatened premature birth; a prematurity knowledge questionnaire and the State-Trait Anxiety Inventory were administered after counseling but before delivery. RESULT: Across all gestational-ages, participants were more aware of short-term problems than long-term problems. With increasing gestational age the knowledge of long-term problems decreased (P=0.01). Maternal knowledge was 82% for gestational ages where clear guidelines exist regarding goal of counseling and information that should be provided to the parents. CONCLUSION: Most mothers of early-moderate premature infants are not aware of the potential for long-term problems. Guidelines, which outline the information that should be provided to parents, may improve maternal knowledge after counseling.

Underwater attachment in current: the role of setose attachment structures on the gills of the mayfly larvae Epeorus assimilis (Ephemeroptera, Heptageniidae).

Setose pads of aquatic Epeorus assimilis larvae are specialised structures located ventrally on the part of the gill lamella contacting the substrate and were suggested to have an attachment function in strong currents. In order to test the role of these setose pads in underwater attachment for the first time, we measured friction (shear) forces generated by the gill lamellae on solid substrates. Moreover, the influence of a different kind of surface roughness on attachment was investigated. Scanning electron microscopy showed that four different seta types can be found on the pads. Our results revealed that the pads significantly contributed to friction force generated on smooth and on some rough substrates but not on certain surfaces of intermediate roughness. The contribution of pads to the friction coefficient in experiments was lower than expected under natural conditions, which may be caused by a smaller contact area between the pads and the substrate (changes in material properties, lack of the active control of body positioning of the larva). The friction coefficient of the gill lamellae with the substrate depended on the surface roughness of the substrate and on the pulling direction. These results suggest that interlocking between structures of the insect cuticle and substrate irregularities, as well as molecular adhesion, contribute to friction.

A description of preschool neuropsychological assessment in the P.I.N.T. Clinic after the first 5 years.

Assessment of preschool-aged children constitutes a dilemma for many neuropsychologists because of a limited set of standardized measures with normative data as well as inadequate understanding of typical developmental trajectories for neuropsychological functions during the first years of life. However, numerous neurological disorders, medical disorders with central nervous system involvement, and even psychiatric disorders have their onset during this time and subsequently impact cognition by altering functional developmental trajectories. Comprehensive neuropsychological evaluations can help to delineate this alteration in developmental trajectory and assist in determining need for specific interventions services so that they can be implemented early as possible in hopes of reducing developmental cognitive impairments. In this descriptive report, potential preschool neuropsychological evaluation procedures are described and a discussion of appropriate reasons for referral and pertinent testing considerations is presented. Additionally, the Preschool and Infant Neuropsychology (P.I.N.T.) Clinic is presented to describe a methodology for conducting preschool neuropsychological assessment.

Genetic and epigenetic changes in human epithelial cells immortalized by telomerase.

Exogenous expression of hTERT, the catalytic component of telomerase, is sufficient for the immortalization of human fibroblasts but insufficient for the immortalization of human foreskin keratinocytes (HFKs) and human mammary epithelial cells (HMECs). These latter cell types can overcome senescence by coexpression of hTERT and human papillomavirus (HPV) E7 or by expression of hTERT and loss of p16(INK4a) expression, indicating that the retinoblastoma (Rb) pathway, along with a telomere maintenance pathway, plays a role in determining the life span of epithelial cells. In this study, we further characterize hTERT-immortalized HFKs and human adenoid epithelial cells (HAKs) for genotypic and phenotypic alterations that are associated with immortalization. Of five hTERT-immortalized HFK and HAK cell lines examined, four exhibited repression of p16(INK4a) expression by promoter methylation or specific large-scale deletion of chromosome 9p, the location of p16(INK4a). Interestingly, one cell line exhibited complete down-regulation of expression of p14(ARF), with only slight down-regulation of expression of p16(INK4a). Yet, all of the immortal cells lines exhibited hyperphosphorylated Rb. Cytogenetic analysis revealed clonal chromosome aberrations in three of the five cell lines. All of the cell lines retained a growth block response with the expression of mutant ras. When grown on organotypic raft cultures, however, the hTERT-immortalized cells exhibited a maturation delay on terminal differentiation. Our results indicate that immortalization of epithelial cells may require both activation of telomerase and other genetic and/or epigenetic alterations that abrogate normal differentiation.

The role of ion regulation in the control of the distribution of Gammarus tigrinus (Sexton) in salt-polluted rivers.

Fluctuating salinities at different sites on the German salt-polluted rivers Werra and Weser were compared with extracellular ion levels of specimens of Gammarus tigrinus (Sexton; Amphipoda, Crustacea), collected at the same sites. G. tigrinus regulated haemolymph concentrations of inorganic anions (Cl-, SO(4)2-, PO(4)3-) and cations (Na+, K+, Mg2+, Ca2+) during fluctuations of salt pollution in the upper Weser. This capacity to regulate varying levels of salt pollution in the upper Weser, correlated well with the distribution of the brackish amphipods in this river ecosystem. G. tigrinus tolerated periods of Na+ and Cl- stress (> 380 mmol l-1) without compensating these maxima by regulating extracellular Na+ and Cl-. However, during such bursts of Na+ and Cl- stress in Werra and Weser, the ability to regulate extracellular [K+] at river water K+ stress of > or = 6.0 mmol l-1 may explain why this brackish species has been more successful in these rivers than its competitors like Gammarus pulex. The present investigation demonstrates that the water salinity affects the [NO3-] in the haemolymph of G. tigrinus. With increasing hypo-osmotic stress the animals accumulate increasing amounts of NO3-. A simultaneous increase in stream water [NO3-] causes an additional accumulation of NO3- in the haemolymph. The high extent of accumulation indicates that active ion transport systems may be involved. The accumulation of NO3- in the haemolymph has low physiological consequences to G. tigrinus, but when hypo-osmotically stressed under anoxic conditions, nitrite formed by the reduction of nitrate may have an adverse affect on the metabolism of G. tigrinus.

Both Rb/p16INK4a inactivation and telomerase activity are required to immortalize human epithelial cells.

Normal human cells undergo a limited number of divisions in culture and enter a non-dividing state called replicative senescence. Senescence is accompanied by several changes, including an increase in inhibitors of cyclin-dependent kinases and telomere shortening. The mechanisms by which viral oncogenes reverse these processes are not fully understood, although a general requirement for oncoproteins such as human papillomavirus E6 and E7 has suggested that the p53 and Rb pathways are targeted. Expression of the catalytic component of telomerase, hTERT, alone significantly extends the lifespan of human fibroblasts. Here we show that telomerase activity is not sufficient for immortalization of human keratinocyte or mammary epithelial cells: we find that neither addition of hTERT nor induction of telomerase activity by E6, both of which are active in maintaining telomere length, results in immortalization. Inactivation of the Rb/p16 pathway by E7 or downregulation of p16 expression, in combination with telomerase activity, however, is able to immortalize epithelial cells efficiently. Elimination of p53 and of the DNA-damage-induced G1 checkpoint is not necessary for immortalization, neither is elimination of p19ARF.

[Effects of the nature of energy in food and use of anabolic agents on the quality of veal]. / Influence de la forme d'apport de l'énergie dans la ration et de l'utilisation d'anabolisants sur la qualité de la viande de veau.

The effects of the nature of energy intake, of the slaughter weight and of the use of hormones on the quality of veal meat were studied. Concerning the colour of meat, the use of hormones has no effect either on the pigment content or on the ultimate pH, but the nature of energy intake and the slaughter weight can affect these two parameters. With the increase of the slaughter weight and the substitution of lipids by starch in the diet, the probability to get a redder meat increases. For a given carcass weight, the use of hormones goes with a significant decrease of the tenderness of meat.