Carbazate modified dextrans as scavengers for carbonylated proteins

A series of biocompatible and non- toxic polysaccharide molecules have been successfully fabricated and explored their potential application for scavenging the carbonyl species in vitro. These macromolecules were dextrans with different hydrazide substitution ratios determined by TNBS assay, NMR and FTIR characterization. The colorimetric assay had demonstrated that these macromolecules could effectively scavenge acrolein, oxidized bovine serum albumin (BSA) in buffer solutions as well as carbonyl proteins from serum. The scavengers could achieve twice more scavenging effects for modified dextrans with high molecular weight (Mw = 100,000) than those of low ones (Mw = 40,000) with the same substitution ratio. Protein gel electrophoresis confirmed that the formation of the complex between carbonyls and modified dextrans resulted in appearance of slower bands. It also revealed that such macromolecules could protect cultured cells against the toxicity of acrolein or its derivatives. The proposed macromolecules indicated a very promising capability as scavengers for oxidative stress plus its derivatives without side effects.

ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization

Three different polymers were synthesized and evaluated as solid polymer electrolytes: poly(ε-caprolactone) (PCL), polystyrene-poly(ε-caprolactone) (SC), and polystyrene-poly(ε-caprolactone-r-trimethylene carbonate) (SCT).

Sutures impregnated with carbazate-activated polyvinyl alcohol reduce intraperitoneal adhesions

BACKGROUND

Intraperitoneal adhesions cause significant morbidity. They occur after peritoneal trauma, which induces oxidative stress with production of inflammatory cytokines, peroxidized proteins (carbonyls) and lipids (aldehydes). This study aimed to investigate if carbazate-activated polyvinyl alcohol (PVAC), an aldehyde-carbonyl inhibitor, can reduce intraperitoneal adhesions in an experimental model.

MATERIAL AND METHODS

Male Sprague-Dawley rats (n=110) underwent laparotomy, cecal abrasion and construction of a small bowel anastomosis. They either were treated with intraperitoneal instillation of PVAC or were sutured with PVAC-impregnated sutures. Thromboelastography analysis was performed using human blood and PVAC. The lipid peroxidation product malondialdehyde (MDA) and inflammatory cytokines IL-1β and IL-6 were quantified in peritoneal fluid. At day 7, bursting pressure of the anastomosis was measured and adhesions were blindly scored.

RESULTS

PVAC in human blood decreased the production of the fibrin-thrombocyte mesh without affecting the coagulation cascade. MDA, IL-1β and IL-6 were increased after 6h without significant difference between the groups. PVAC-impregnated sutures reduced intraperitoneal adhesions compared to controls (p=0.0406) while intraperitoneal instillation of PVAC had no effect. Anastomotic bursting pressure was unchanged.

CONCLUSIONS

Intervention with an aldehyde-carbonyl inhibitor locally in the wound by PVAC-impregnated sutures might be a new strategy to reduce intraperitoneal adhesions.

A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries

We report here a water-based functional binder framework for the lithium-sulfur battery systems, based on the general combination of a polyether and an amide-containing polymer. These binders are applied to positive electrodes optimised towards high-energy electrochemical performance based only on commercially available materials. Electrodes with up to 4 mAh cm^-2 capacity and 97-98 % coulombic efficiency are achievable in electrodes with a 65 % total sulfur content and a poly(ethylene oxide):poly(vinylpyrrolidone) (PEO:PVP) binder system. Exchange of either binder component for a different polymer with similar functionality preserves the high capacity and coulombic efficiency. The improvement in coulombic efficiency from the inclusion of the coordinating amide group was also observed in electrodes where pyrrolidone moieties were covalently grafted to the carbon black, indicating the role of this functionality in facilitating polysulfide adsorption to the electrode surface. The mechanical properties of the electrodes appear not to significantly influence sulfur utilisation or coulombic efficiency in the short term but rather determine retention of these properties over extended cycling. These results demonstrate the robustness of this very straightforward approach, as well as the considerable scope for designing binder materials with targeted properties.

The application of protein microarray assays in psychoneuroimmunology

Protein microarrays are miniaturized multiplex assays that exhibit many advantages over the commonly used enzyme-linked immunosorbent assay (ELISA). This article aims to introduce protein microarrays to readers of Brain, Behavior, and Immunity and demonstrate its utility and validity for use in psychoneuroimmunological research. As part of an ongoing investigation of psychological and behavioral influences on influenza vaccination responses, we optimized a novel protein microarray to quantify influenza-specific antibody levels in human sera. Reproducibility was assessed by calculating intra- and inter-assay coefficients of variance on serially diluted human IgG concentrations. A random selection of samples was analyzed by microarray and ELISA to establish validity of the assay. For IgG concentrations, intra-assay and inter-assay precision profiles demonstrated a mean coefficient of variance of 6.7% and 11.5% respectively. Significant correlations were observed between microarray and ELISA for all antigens, demonstrating the microarray is a valid alternative to ELISA. Protein microarrays are a highly robust, novel assay method that could be of significant benefit for researchers working in psychoneuroimmunology. They offer high throughput, fewer resources per analyte and can examine concurrent neuro-immune-endocrine mechanisms.

Pre-incubation of chemically crosslinked hyaluronan-based hydrogels, loaded with BMP-2 and hydroxyapatite, and its effect on ectopic bone formation

The effects of pre-incubation of hyaluronan hydrogels, for different lengths of time after the initiation of chemical crosslinking and prior to injection, were explored both by investigating the in vitro BMP-2 release kinetics from the hydrogel and by studying the ectopic bone formation in rats. From the curing profile, obtained from rheological analysis, appropriate pre-incubation times (1 min, 5 h and 3 days) were selected, to prepare slightly, moderately and fully cured hydrogels. Comparable release profiles were observed for all three test groups in vitro. Furthermore, radiography, pQCT and histology of the explanted grafts showed cancellous bone formation in all groups after 5 weeks in vivo. However, longer pre-incubation times gave rise to an increase in bone volume, but a decrease in bone density. Moreover, the 5 h and the 3 days grafts appeared to be more ordered and resistant to deformation from the surrounding tissue than the 1 min grafts. The observed variations in mechanical and biological properties could potentially be used to adapt the treatment for a specific indication.

Morphological differences in BMP-2-induced ectopic bone between solid and crushed hyaluronan hydrogel templates

The possibility to affect bone formation by using crushed versus solid hydrogels as carriers for bone morphogenetic protein 2 (BMP-2) was studied. Hydrogels, based on chemical crosslinking between hyaluronic acid and poly(vinyl alcohol) derivatives, were loaded with BMP-2 and hydroxyapatite. Crushed and solid forms of the gels were analyzed both in vitro via a release study using ¹²⁵I radioactive labeling of BMP-2, and in vivo in a subcutaneous ectopic bone model in rats. Dramatically different morphologies were observed for the ectopic bone formed in vivo in the two types of gels, even though virtually identical release profiles were observed in vitro. Solid hydrogels induced formation of a dense bone shell around non-degraded hydrogel, while crushed hydrogels demonstrated a uniform bone formation throughout the entire sample. These results suggest that by crushing the hydrogel, the construct's three-dimensional network becomes disrupted. This could expose unreacted functional groups, making the fragment's surfaces reactive and enable limited chemical fusion between the crushed hydrogel fragments, leading to similar in vitro release profiles. However, in vivo these interactions could be broken by enzymatic activity, creating a macroporous structure that allows easier cell infiltration, thus, facilitating bone formation.

Characterization of recombinant human bone morphogenetic protein-2 delivery from injectable hyaluronan-based hydrogels by means of 125I-radiolabelling

This study presents a thorough in vitro and in vivo characterization of the delivery of bone morphogenetic protein 2 (BMP-2) from a hyaluronan-based hydrogel system. The in vitro release of BMP-2 from similar hydrogels has previously been studied by enzyme-linked immunosorbent assay (ELISA), by which only a fraction of the loaded protein is detected. In the current study, (125) I radiolabelling was used instead to monitor BMP-2 in vitro and in vivo. To minimize protein loss during handling, (125) I-BMP-2 adsorption to different tubes was studied at different times and temperatures. The data showed that Protein LoBind tubes exhibited the lowest protein affinity. Furthermore, a biphasic release profile of biologically active BMP-2 was observed both in vitro and in vivo, with the initial fast phase during the first week, followed by a slower release during the remaining 3 weeks. The initial fast-release phase corresponded to the early bone formation observed after 8 days in an ectopic model in rats. Bone volume and mineral content increased until day 14, after which a decrease in bone volume was observed, possibly due to resorption in response to decreased amounts of released BMP-2. Overall, the results suggested that cautious protein handling and a reliable quantification technique are essential factors for successful design of a BMP-2 delivery system.

Biocompatible and biodegradable phosphorylcholine ionomers with reduced protein adsorption and cell adhesion

In this paper a recently developed biodegradable phosphorylcholine ionomer (PC ionomer) was evaluated in different biological environments with a focus on the adsorption of proteins (fibrinogen) and the adhesion of cells. Our results have shown that the polar phosphoryl choline (PC) group may be enriched at the surface of cast films with an added hydrophilic environment. X-ray photoelectron spectroscopy confirmed the surface depletion of PC groups in dry conditions, as nitrogen and phosphorous atoms were found in the bulk of the material but not at the outermost surface layer. The surface enrichment leads to a strongly hydrophilic surface that prevents the adsorption of proteins and reduces the adhesion of cells. The non-functional and hydrophobic reference poly(trimethylene carbonate) (PTMC) adsorbs both proteins and cells, thus the wetting and low adhesion behavior of the PC ionomer can be attributed to the introduced PC functionality. Since the in vivo acceptance of biomaterials is determined by their ability to withstand protein adsorption the PC ionomer described in this paper is highly interesting for a number of in vivo applications in which the adsorption of proteins may be critical, for example, blood contact events.

Contact lens profile: a tale of two countries

INTRODUCTION

This study investigated the modality, type and duration of contact lens wear as well as compliance and hygiene related issues (hand and case hygiene, use of tap water, dozing and overnight wear) in the UK and Germany. Questionnaires were collected anonymously from 417 UK and 767 German patients attending optometric practices for contact lens appointments. It is the seventh of a series of contact lens wearer profiles conducted since 2000.

RESULTS

The proportion of rigid gas permeable lenses worn was significantly higher at 55.4% in Germany, compared to 16.1% in the UK. Overall, a significantly larger proportion of German participants used tap water to rinse their lenses and cases (P<0.001). Also, German respondents changed their lens cases less frequently (p<0.001). Fewer UK than German respondents stated they washed their hands before lens insertion (p=0.009), removal (p=0.01), before eating (p<0.001). German participants were less likely to wash their hands before preparing food (p=0.042) and after using the toilet (p=0.002). The two sample groups differed significantly regarding the care regimens they used for their CLs (p<0.001).

CONCLUSION

The differences between Germany and the UK highlighted in this study were caused by differences in legal regulations, plumbing and practitioners' guidance. Although many of the questions relating to hygiene differed statistically between the two participating sample groups, the absolute differences in figures were not considered to be large.

Enhanced neuronal differentiation in a three-dimensional collagen-hyaluronan matrix

Efficient 3D cell systems for neuronal induction are needed for future use in tissue regeneration. In this study, we have characterized the ability of neural stem/progenitor cells (NS/PC) to survive, proliferate, and differentiate in a collagen type I-hyaluronan scaffold. Embryonic, postnatal, and adult NS/PC were seeded in the present 3D scaffold and cultured in medium containing epidermal growth factor and fibroblast growth factor-2, a condition that stimulates NS/PC proliferation. Progenitor cells from the embryonic brain had the highest proliferation rate, and adult cells the lowest, indicating a difference in mitogenic responsiveness. NS/PC from postnatal stages down-regulated nestin expression more rapidly than both embryonic and adult NS/PC, indicating a faster differentiation process. After 6 days of differentiation in the 3D scaffold, NS/PC from the postnatal brain had generated up to 70% neurons, compared with 14% in 2D. NS/PC from other ages gave rise to approximately the same proportion of neurons in 3D as in 2D (9-26% depending on the source for NS/PC). In the postnatal NS/PC cultures, the majority of betaIII-tubulin-positive cells expressed glutamate, gamma-aminobutyric acid, and synapsin I after 11 days of differentiation, indicating differentiation to mature neurons. Here we report that postnatal NS/PC survive, proliferate, and efficiently form synapsin I-positive neurons in a biocompatible hydrogel.

Molecular dynamics of a biodegradable biomimetic ionomer studied by broadband dielectric spectroscopy

Broadband dielectric spectroscopy was used to investigate the bulk molecular dynamics of a recently developed biodegradable biomimetic ionomer potentially useful for biomedical applications. Isothermal dielectric spectra were gathered for a phosphoryl choline (PC)-functionalized poly(trimethylene carbonate) (PTMC) ionomer and unfunctionalized PTMC at temperatures ranging from 2 to 60 degrees C over a broad frequency range of 10(-3) to 10(6) Hz. Four relaxations were clearly identified, two of which were shown to stem from the PTMC polymer backbone. A detailed analysis showed that the formation of zwitterionic aggregates was responsible for the material's bulk functionality and that bulk conduction processes may provide useful information for assessing the PC ionomer as a candidate for drug delivery applications. Finally, it was concluded that absorbed water concentrates around the aggregates, resulting in an increased mobility of the PC end-groups.

Hyaluronic acid derivatives prepared in aqueous media by triazine-activated amidation

A method is presented for the preparation of hyaluronic acid derivatives obtained through triazine-activated amidation. A number of amines were successfully reacted with hyaluronic acid carboxyl groups using 2-chloro-4,6-dimethoxy-1,3,5-triazine as an activating species in a mixture of water and acetonitrile under neutral conditions. By varying the amount of triazine reagent, it was possible to control the degree of modification. Depending on the amine chosen, degrees of modification ranging from 3 to 20% were obtained when using 0.5 equiv of the triazine to hyaluronic acid carboxyl groups. The possibility to perform the reaction in a mixture of water and acetonitrile facilitates the introduction of a wide range of both hydrophilic and hydrophobic amines. Triazine-activated amidation appears to be a highly versatile, controllable, and relatively mild technique for modification of hyaluronic acid, and we predict that it will be useful in the design of novel hyaluronic acid based biomaterials.

Synthesis of Highly Elastic Biodegradable Poly(urethane urea)

Linear poly(urethane urea) containing a biodegradable soft segment and a hard segment built solely from methyl-2,6-diisocyanatehexanoate (LDI) is presented, using a procedure where no chain extender is required. By having LDI in excess, together with a soft segment, and adding water in the vapor phase continuously creates amines in situ resulting in hard segments containing multiple LDI units linked via urea linkages. As soft segments, polymers of trimethylene carbonate (TMC) and copolymers of TMC, epsilon-caprolactone, and D,L-lactic acid (DLLA) were used. High inherent viscosity, 0.95-1.65 dL/g, was afforded even when DLLA-containing soft segments were used, which usually undergo aminolysis. With a hard segment content between 12% and 18%, all of the materials showed very high elongation at breakage, ranging from 1600% to 4700%, and an elastic modulus from 2.1 to 140 MPa. This one-pot synthesis is simple and has now been shown to be applicable to a large number of systems.

Photoelectron spectroscopy studies of the functionalization of a silicon surface with a phosphorylcholine-terminated polymer grafted onto (3-aminopropyl)trimethoxysilane

The structure of a biomimetic phosphorylcholine (PC)-functionalized poly(trimethylene carbonate) (PC-PTMC-PC), linked to a silicon substrate through an aminolysis reaction at 120 degrees C with (3-aminopropyl)trimethoxysilane (APTMS), was studied using photoelectron spectroscopy. Two chemical states were found for the unreacted APTMS amine, a neutral state and a protonated state, where the protonated amine on average was situated closer to the silicon substrate than the neutral amine. The experiments also indicated the presence of a third chemical state, where amines interact with unreacted silanol groups. The PTMC chains of the grafted films were found to consist of only 2-3 repeat units, with the grafted chains enriched in the zwitterionic end group, suggesting that these groups are attracted to the surface. This was further supported by the experiments showing that the PC groups were situated deeper within the film.

Synthetic Biodegradable Ionomers that Engulf, Store, and Deliver Intact Proteins

Telechelic anionic and cationic biodegradable ionomers capable of loading, storing, and releasing proteins are presented. Two different ionomers have been synthesized with either anionic or cationic end groups. The reaction was done quantitatively as shown by (1)H NMR. The swelling properties of the hydrophobic poly(trimethylene carbonate) polymer are contributed to the ionic end groups that display hydrophilic properties. Depending on the molecular weight of the ionomer, and also on the ionic charge, the materials swell differently in water, from approximately 50% for M(w) = 12 000 g/mol to approximately 500% when dealing with 2000 g/mol. The high swelling led us to believe that it would be possible to load and release proteins preferably in a still active form. As models, two different proteins were chosen: hemoglobin and cytochrome c. The swelling and release study shows that both ionomers possess the capability to adsorb and later release the proteins with retained structure. Release measurements from both the swollen and dried states have been evaluated with similar results, showing that the dried state seems to release a little bit less than the swollen one. These kinds of materials should be interesting for a wide variety of applications where drug and protein release is wanted, as well as in applications such as protein separation media.

What the patient wore, and why …

This study set out to compare the wearing habits and attitudes of patients today with those, featured in a study by Cross, fitted prior to 1949. Information was sought in the present time regarding the age, occupation and sex of the wearers in 10 different categories of lens types currently available. The views of the patients were also sought regarding the comfort, distance vision, close vision, convenience and how the present lenses met their expectations. Motivation to wear contact lenses was also compared between the two studies. Results show a considerable change in the age of wearers both at the time of fitting and at the time of the studies, occupations of the wearers, and wearing modalities. Most of all it highlights the huge amount of choice available to the modern wearer, not only in lens types and materials, but also in the location and type of practice fitting lenses now at very much lower costs. Wearing times tend to have dropped since 1949 but through choice rather than necessity.

Immunostimulation of larvae and juveniles of cod, Gadus morhua L

Cod larval culture is currently hampered by high mortalities in the first 2-3 weeks after hatching, often due to infectious diseases. The immune system of cod is not fully competent until 2-3 months after hatching. Conventional vaccination is, therefore, not of value before this time, and the larvae are wholly reliant on non-specific parameters for their defence against infection. A range of substances, generally derived from bacterial, fungal or plant origin, can activate these non-specific parameters. During three hatching seasons, 2001-2003, at the Marine Institute's Experimental Station, Stadur, Grindavik, Iceland, the effects of several immunostimulants on survival and disease resistance of cod larvae and juveniles were examined. Both bathing treatments and administration in the feed were used. One of these substances, lipopolysaccharide (LPS), isolated from the bacterium Aeromonas salmonicida (ssp. salmonicida or achromogenes), appeared in some instances to improve survival and have a beneficial effect on disease resistance. Other substances tested had limited effects. The results emphasize the need for further work in this field.

Complement component C3 transcription in Atlantic halibut (Hippoglossus hippoglossus L.) larvae

The complement systems of fish are well developed and play an important role in the innate immune response. Complement C3 is the central protein of all three activation pathways and is the major opsonin of the complement system and essential for the generation of the membrane attack complex. A 1548 bp part of complement component C3 was isolated from a halibut liver cDNA library by immunoscreening. The deduced amino acid sequence showed that this part of halibut C3 contained key amino acids for factor H, I and properdin binding as well as two N-glycosylation sites. Digoxigenine labelled mRNA probes were synthesised and the transcription of C3 was monitored in three larval stages at 206, 430 and 1000 degrees d (30, 50 and 99 days post hatching), by in situ hybridisation. C3 mRNA was detected in muscle, liver, brain, chondrocytes, spinal cord, eye, intestines, oesophagus and kidney. These findings are in accordance with a former immunohistochemical study on halibut C3 protein ontogeny, indicating that C3 is indeed locally expressed in many organs from the youngest stages on. Complement may thus be linked to the formation and generation of different organs during development and play an important role in the early immune response of halibut larvae.

Organo Hydrogel Hybrids. Formation of Reservoirs for Protein Delivery

A biodegradable organo hydrogel hybrid material is presented, which is formed through the water uptake of a phosphoryl choline zwitterionomer (PC ionomer). The water uptake and subsequent swelling is induced by the phosphoryl choline (PC) end group functionality. The nonfunctional poly(trimethylene carbonate) is hydrophobic and as such does not absorb any water. Disks of the PC ionomer showed significant water uptake, typically above 90 wt % when fully swollen. This high water uptake triggered us to utilize the material for drug and protein loading and subsequent release. Fluorescein and fluorescein-labeled proteins were used as simple models for the loading and release characteristics of the material which was studied by fluorescence spectroscopy. The rate of release of the loaded molecules was compared, and it was shown that the release rate was similar for FITC and insulin but slightly slower for albumin. These results suggest that the PC ionomer may be used as a biodegradable and low elastic modulus material with an additional drug and/or protein release capacity. Such materials are of particular interest for use in a variety of applications in vivo, for example as drug eluting stents.

Phosphoryl Choline Introduces Dual Activity in Biomimetic Ionomers

Dual activity of phosphoryl choline (PC) functional poly(trimethylene carbonate) (PTMC) was found which induces the zwitterionic biomimetic PC group to form physical cross-links with ionomers in the bulk, and at the same time enrich at the surface of cast films. The formation of zwitterionic domains from a bifunctional PC-PTMC-PC (ionomer) provided firm films with a low elastic modulus in contrast to the tacky PTMC starting material (Mn approximately 3900 g/mol) with poor mechanical performance. In addition, the ionomer possessed improved hemocompatible properties that was explained by the enrichment of PC at the surface, suggesting a way to tailor the mechanical performance of biodegradable PTMC-based ionomers while providing its bioactivity. Tailored elasticity while maintaining hemocompatibility of a biodegradable ionomer should be of particular interest for a variety of in vivo applications.

JunB negatively regulates AP-1 activity and cell proliferation of malignant mouse keratinocytes

OBJECTIVE

Previously we have shown that a malignant mouse keratinocyte cell line, 10Gy5, has elevated AP-1 transactivation and reduced JunB protein levels compared to its parental benign cell line, 308, and that the tumorigenicity in the 10Gy5 cells could be blocked by a dominant negative c-Jun mutant protein. We wished to determine whether the change in JunB protein levels could account for the elevated AP-1 activity and whether re-expression of JunB in malignant 10Gy5 cells altered their proliferative capacity.

DESIGN

In the current study, we reduced JunB expression in benign 308 cells with antisense oligonucleotides and increased JunB expression in malignant 10Gy5 cells by stable transfection of a JunB expression vector.

RESULTS

Increased AP-1 activity was detected after treatment of the benign 308 cell line with JunB antisense oligonucleotides that reduced JunB protein levels. Stably JunB-transfected clones of malignant 10Gy5 cells showed decreased AP-1 activity, slowed in vitro cell proliferation and reduced tumor growth when xenografted to athymic nude mice.

CONCLUSION

These findings suggest that expression of JunB protein has a negative effect on malignant tumor cell proliferation in part through its ability to inhibit AP-1 transactivation.

A computerized social cognitive intervention for nutrition behavior: direct and mediated effects on fat, fiber, fruits, and vegetables, self-efficacy, and outcome expectations among food shoppers

This study examined the direct and mediated impact of a self-administered, computer-based intervention on nutrition behavior self-efficacy, and outcome expectations among supermarket food shoppers. The intervention, housed in kiosks in supermarkets and based on social cognitive theory, used tailored information and self-regulation strategies delivered in 15 brief weekly segments. The study sample (N = 277), stratified and randomly assigned to treatment or control, was 96% female, was 92% White, had a median annual income of about $35,000, and had a mean education of 14. 78 +/- 2.11 years. About 12% of the sample reported incomes of $20,000 or less, and about 20% reported 12 years or fewer of education. Analysis of covariance immediately after intervention and at a 4- to 6-month follow-up found that treatment led to improved levels of fat, fiber, and fruits and vegetables. Treatment also led to higher levels of nutrition-related self-efficacy, physical outcome expectations, and social outcome expectations. Logistic regression analysis determined that the treatment group was more likely than the control group to attain goals for fat, fiber, and fruits and vegetables at posttest and to attain goals for fat at follow-up. Latent variable structural equation analysis revealed self-efficacy and physical outcome expectations mediated treatment effects on nutrition. In addition, physical outcome expectations mediated the effect of self-efficacy on nutrition outcomes. Implications for future computer-based health promotion interventions are discussed.

Lymph node homing cells biologically enriched for gamma delta T cells express multiple genes from the T19 repertoire

Sheep gamma delta T cells have been shown serologically to express T19, a membrane protein of 180-200 kDa which is a member of the scavenger receptor superfamily. Previous work from this laboratory resulted in the detection of a multigene family of T19-like genes in the sheep genome. In this study nucleotide sequences from several T19 genes were determined and are reported along with the corresponding segments of a number of expressed mRNA molecules. A segment of a single sheep T19-like gene was sequenced and these data, along with the corresponding sequences from cloned T19-like cDNA molecules from sheep and cow, were used to design an oligonucleotide primer system suitable for amplification of corresponding segments of many T19 genes and their cDNAs. Between 30 and 40% of cloned T19 genes were amenable to amplification using the selected primers, and sequence analysis of cloned PCR products confirmed that different T19 genes encode unique amino acid sequences. The expression of multiple T19 genes was established using cDNA molecules obtained from a single sample of sheep lymphocyte mRNA. The possible role of the T19 family of genes is discussed.

A computational method for determination of the individual anaerobic threshold

The individual anaerobic threshold (IAT) has received attention recently in the field of exercise physiology. The IAT is defined as the point during progressive exercise when lactate elimination from the blood is both maximal and equal to the diffusion from the working muscles. It has been theorized that an individual can maintain exercise for relatively long periods when working at the IAT. A common method for determination of the IAT is to perform a visual determination from plots of lactate concentration versus power output. This paper briefly describes the theoretical basis for determination of the IAT and presents an algorithm for its accurate calculation.

Perspective taking and theory of mind: do children predict interpretive diversity as a function of differences in observers' knowledge?

In 3 experiments, children's ability to vary their responses on perspective-taking tasks as a function of the other person's age was examined. In Experiment 1,4- and 5-year-olds were shown to be accurate in their judgments about the knowledge of a 6-month-old baby, a 4-year-old child, and an adult. In Experiment 2, 4-year-olds were asked to determine if a baby, child, and adult would be able to identify an object from a restricted view showing either an identifiable part, a small nondescript part, or no part of the object. Children tended to report that the observer would be able to identify the object from an identifiable or nondescript part. Their judgments were not affected by the age of the observer. Experiment 3 replicated the asymmetry in performance on the general knowledge task and the restricted view task and extended these results by testing 4-year-olds, 6-year-olds, and adults using a within-subjects design.

Back pain in helicopter aircrew: a literature review

Back pain in helicopter aircrew has been reported by the med services of many countries. The problem is compared to the similar phenomenon of back pain in civilian industrial groups, particularly drivers and the operators of heavy equipment. In both drivers and helicopter aircrew, posture and vibration exposure have been identified as causes of the back pain. The significance of these factors, and the mechanisms that relate them to the discomfort, and possible solutions are discussed.