Monospecific high-affinity and complement activating anti-GM1 antibodies are determinants in experimental axonal neuropathy

It has been difficult to replicate consistently the experimental model of axonal Guillain-Barré syndrome (GBS). We immunized rabbits with two lipo-oligosaccharides (LOS1 and LOS2) derived from the same C. jejuni strain and purified in a slightly different way. LOS1 did not contain proteins whereas several proteins were present in LOS2. In spite of a robust anti-GM1 antibody response in all animals the neuropathy developed only in rabbits immunized with LOS1. To explain this discrepancy we investigated fine specificity, affinity and ability to activate the complement of anti-GM1 antibodies. Only rabbits immunized with LOS1 showed monospecific high-affinity antibodies which activated more effectively the complement. Although it is not well understood how monospecific high-affinity antibodies are induced these are crucial for the induction of experimental axonal neuropathy. Only a strict adherence to the protocols demonstrated to be successful may guarantee the reproducibility and increase the confidence in the animal model as a reliable tool for the study of the human axonal GBS.

Antifibrotic effects of tocotrienols on human Tenon's fibroblasts

Antifibrotic effects of α- (40, 60, 80, 100, and 120 μM), γ- (10, 20, 30, and 40 μM) and δ-tocotrienol (10, 20, 30, and 40 μM) on hTf cultures were evaluated by performing proliferation, migration and collagen synthesis assays. Whereas for vitamin E the exposure time was set to 7 days to mimic subconjunctival application, cultures were exposed only 5 min to mitomycin C 100 μg/ml to mimic intraoperative administration. Cell morphology (phase contrast microscopy) as an assessment for cytotoxicity and cell density by measuring DNA content in a fluorometric assay to determine proliferation inhibition was performed on day 0, 4, and 7. Migration ability and collagen synthesis of fibroblasts were measured. Results All tested tocotrienol isoforms were able to significantly inhibit hTf proliferation in a dose-dependent manner (maximal inhibitory effect without relevant morphological changes at day 4 for α-tocotrienol 80 μM with 36.7% and at day 7 for α-tocotrienol 80 μM with 42.6% compared to control). Degenerative cell changes were observed in cultures with concentrations above 80 μM for α- and above 30 μM for γ- and δ-tocotrienol. The highest collagen synthesis inhibition has been found with 80 µM α-tocotrienol (62.4%) and no significant inhibition for mitomycin C (2.5%). Migration ability was significantly reduced in cultures exposed to 80 µM α- and 30 µM γ-tocotrienol (inhibition of 82.2% and 79.5%, respectively, compared to control) and also after mitomycin C treatment (60.0%). Complete growth inhibition without significant degenerative cell changes could only be achieved with mitomycin C. Conclusion In vitro, all tested tocotrienol isoforms were able to inhibit proliferation, migration and collagen synthesis of human Tenon’s fibroblasts and therefore may have the potential as an anti-scarring agent in filtrating glaucoma surger

Biomechanical model of human cornea based on stromal microstructure

The optical characteristics of the human cornea depends on the mechanical balance between the intra-ocular pressure and intrinsic tissue stiffness. A wide range of ophthalmic surgical procedures alter corneal biomechanics to induce local or global curvature changes for the correction of visual acuity. Due to the large number of surgical interventions performed every day, a deeper understanding of corneal biomechanics is needed to improve the safety of these procedures and medical devices. The aim of this study is to propose a biomechanical model of the human cornea, based on stromal microstructure. The constitutive mechanical law includes collagen fiber distribution based on X-ray scattering analysis, collagen cross-linking, and fiber uncrimping. Our results showed that the proposed model reproduced inflation and extensiometry experimental data [Elsheikh et al., Curr. Eye Res., 2007; Elsheikh et al., Exp. Eye Res., 2008] successfully. The mechanical properties obtained for different age groups demonstrated an increase in collagen cross-linking for older specimens. In future work such a model could be used to simulate non-symmetric interventions, and provide better surgical planning.

Numerical model of the human cornea based on stromal microstructure: identification of mechanical properties for two age groups

The optical quality of the human eye mainly depends on the refractive performance of the cornea. The shape of the cornea is a mechanical balance between intraocular pressure and tissue intrinsic stiffness. Several surgical procedures in ophthalmology alter the biomechanics of the cornea to provoke local or global curvature changes for vision correction. Legitimated by the large number of surgical interventions performed every day, the demand for a deeper understanding of corneal biomechanics is rising to improve the safety of procedures and medical devices. The aim of our work is to propose a numerical model of corneal biomechanics, based on the stromal microstructure. Our novel anisotropic constitutive material law features a probabilistic weighting approach to model collagen fiber distribution as observed on human cornea by Xray scattering analysis (Aghamohammadzadeh et. al., Structure, February 2004). Furthermore, collagen cross-linking was explicitly included in the strain energy function. Results showed that the proposed model is able to successfully reproduce both inflation and extensiometry experimental data (Elsheikh et. al., Curr Eye Res, 2007; Elsheikh et. al., Exp Eye Res, May 2008). In addition, the mechanical properties calculated for patients of different age groups (Group A: 65-79 years; Group B: 80-95 years) demonstrate an increased collagen cross-linking, and a decrease in collagen fiber elasticity from younger to older specimen. These findings correspond to what is known about maturing fibrous biological tissue. Since the presented model can handle different loading situations and includes the anisotropic distribution of collagen fibers, it has the potential to simulate clinical procedures involving nonsymmetrical tissue interventions. In the future, such mechanical model can be used to improve surgical planning and the design of next generation ophthalmic devices.

Micromass co-culture of human articular chondrocytes and human bone marrow mesenchymal stem cells to investigate stable neocartilage tissue formation in vitro

Cell therapies for articular cartilage defects rely on expanded chondrocytes. Mesenchymal stem cells (MSC) represent an alternative cell source should their hypertrophic differentiation pathway be prevented. Possible cellular instruction between human articular chondrocytes (HAC) and human bone marrow MSC was investigated in micromass pellets. HAC and MSC were mixed in different percentages or incubated individually in pellets for 3 or 6 weeks with and without TGF-beta1 and dexamethasone (±T±D) as chondrogenic factors. Collagen II, collagen X and S100 protein expression were assessed using immunohistochemistry. Proteoglycan synthesis was evaluated applying the Bern score and quantified using dimethylmethylene blue dye binding assay. Alkaline phosphatase activity (ALP) was detected on cryosections and soluble ALP measured in pellet supernatants. HAC alone generated hyaline-like discs, while MSC formed spheroid pellets in ±T±D. Co-cultured pellets changed from disc to spheroid shape with decreasing number of HAC, and displayed random cell distribution. In -T-D, HAC expressed S100, produced GAG and collagen II, and formed lacunae, while MSC did not produce any cartilage-specific proteins. Based on GAG, collagen type II and S100 expression chondrogenic differentiation occurred in -T-D MSC co-cultures. However, quantitative experimental GAG and DNA values did not differ from predicted values, suggesting only HAC contribution to GAG production. MSC produced cartilage-specific matrix only in +T+D but underwent hypertrophy in all pellet cultures. In summary, influence of HAC on MSC was restricted to early signs of neochondrogenesis. However, MSC did not contribute to the proteoglycan deposition, and HAC could not prevent hypertrophy of MSC induced by chondrogenic stimuli.

The association between extra-curricular sport participation and social anxiety symptoms in children

Social anxiety is a common psychological complaint that can have a significant and long-term negative impact on a child’s social and cognitive development. In the current study, the relationship between sport participation and social anxiety symptoms was investigated. Swiss primary school children (N = 201), parents, and teachers provided information about the children’s social anxiety symptoms, classroom behavior, and sport involvement. Gender differences were observed on social anxiety scores, where girls tended to report higher social anxiety symptoms, as well as on sport activity, where boys engaged in more sport involvement. MANCOVAs with gender as covariant showed no differences in social anxiety symptoms between children involved in an extracurricular sport and those not engaged in sport participation. Nevertheless, children engaged in team sports displayed fewer physical social anxiety symptoms than children involved in individual sports.

Mannan-binding lectin deficiency results in unusual antibody production and excessive experimental colitis in response to mannose-expressing mild gut pathogens

In Crohn's disease (CD) the deficiency of mannan-binding lectin (MBL) is associated with an increased prevalence of anti-Saccharomyces cerevisiae antibodies (ASCA) and with complicated phenotypes of the disease. However, the role of MBL in intestinal inflammation is currently unclear. A study was undertaken to analyse local MBL expression in human intestine and the consequences of MBL deficiency in experimental colitis and yeast infection.

Physical coronary arteriogenesis: a human "model" of collateral growth promotion

In patients with coronary artery disease, the size of myocardial infarction mainly determines the subsequent clinical outcome. Accordingly, it is the primary strategy to decrease cardiovascular mortality by minimizing infarct size. Promotion of collateral artery growth (arteriogenesis) is an appealing option of reducing infarct size. It has been demonstrated in experimental models that tangential fluid shear stress is the major trigger of arterial remodeling and, thus, of collateral growth. Lower-leg, high-pressure external counterpulsation triggered to occur during diastole induces a flow velocity signal and thus tangential endothelial shear stress in addition to the flow signal caused by cardiac stroke volume. We here present two cases of cardiac transplant recipients as human "models" of physical coronary arteriogenesis, providing an example of progressing and regressing clinical arteriogenesis, and review available evidence from clinical studies on other feasible forms of physical arteriogenesis.

Properties of low-threshold motor axons in the human median nerve

This study investigated the excitability and accommodative properties of low-threshold human motor axons to test whether these motor axons have greater expression of the persistent Na(+) conductance, I(NaP). Computer-controlled threshold tracking was used to study 22 single motor units and the data were compared with compound motor potentials of various amplitudes recorded in the same experimental session. Detailed comparisons were made between the single units and compound potentials that were 40% or 5% of maximal amplitude, the former because this is the compound potential size used in most threshold tracking studies of axonal excitability, the latter because this is the compound potential most likely to be composed entirely of motor axons with low thresholds to electrical recruitment. Measurements were made of the strength-duration relationship, threshold electrotonus, current-voltage relationship, recovery cycle and latent addition. The findings did not support a difference in I(NaP). Instead they pointed to greater activity of the hyperpolarization-activated inwardly rectifying current (I(h)) as the basis for low threshold to electrical recruitment in human motor axons. Computer modelling confirmed this finding, with a doubling of the hyperpolarization-activated conductance proving the best single parameter adjustment to fit the experimental data. We suggest that the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel(s) expressed on human motor axons may be active at rest and contribute to resting membrane potential.

Excitability and recruitment patterns of spinal motoneurons in human sleep as assessed by F-wave recordings

This study examines the excitability and recruitment of spinal motoneurons in human sleep. The main objective was to assess whether supraspinal inhibition affects the different subpopulations of the compound spinal motoneuron pool in the same way or rather in a selective fashion in the various sleep stages. To this end, we studied F-conduction velocities (FCV) and F-tacheodispersion alongside F-amplitudes and F-persistence in 22 healthy subjects in sleep stages N2, N3 (slow-wave sleep), REM and in wakefulness. Stimuli were delivered on the ulnar nerve, and F-waves were recorded from the first dorsal interosseus muscle. Repeated sets of stimuli were stored to obtain at least 15 F-waves for each state of vigilance. F-tacheodispersion was calculated based on FCVs using the modified Kimura formula. Confirming the only previous study, excitability of spinal motoneurons was generally decreased in all sleep stages compared with wakefulness as indicated by significantly reduced F-persistence and F-amplitudes. More importantly, F-tacheodispersion showed a narrowed range of FCV in all sleep stages, most prominently in REM. In non-REM, this narrowed range was associated with a shift towards significantly decreased maximal FCV and mean FCV as well as with a trend towards lower minimal FCV. In REM, the lowering of mean FCV was even more pronounced, but contrary to non-REM sleep without a shift of minimal and maximal FCV. Variations in F-tacheodispersion between sleep stages suggest that different supraspinal inhibitory neuronal circuits acting on the spinal motoneuron pool may contribute to muscle hypotonia in human non-REM sleep and to atonia in REM sleep.

Prolonged amelioration of acute lung allograft rejection by sequential overexpression of human interleukin-10 and hepatocyte growth factor in rats

The effect of prolonged electroporation-mediated human interleukin-10 (hIL-10) overexpression 24 hours before transplantation, combined with sequential human hepatocyte growth factor (HGF) overexpression into skeletal muscle on day 5, on rat lung allograft rejection was evaluated. Left lung allotransplantation was performed from Brown-Norway to Fischer-F344 rats. Gene transfer into skeletal muscle was enhanced by electroporation. Three groups were studied: group I animals (n = 5) received 2.5 μg pCIK-hIL-10 (hIL-10/CMV [cytomegalovirus] early promoter enhancer) on day -1 and 80 μg pCIK-HGF (HGF/CMV early promoter enhancer) on day 5. Group II animals (n = 4) received 2.5 μg pCIK-hIL-10 and pUbC-hIL-10 (hIL-10/pUbC promoter) on day -1. Control group III animals (n = 4) were treated by sham electroporation on days -1 and 5. All animals received daily nontherapeutic intraperitoneal dose of cyclosporin A (2.5 mg/kg) and were sacrificed on day 15. Graft oxygenation and allograft rejection were evaluated. Significant differences were found between study groups in graft oxygenation (Pao(2)) (P = .0028; group I vs. groups II and III, P < .01 each). Pao(2) was low in group II (31 ± 1 mm Hg) and in group III controls (34 ± 10 mm Hg), without statistically significant difference between these 2 groups (P = .54). In contrast, in group I, Pao(2) of recipients sequentially transduced with IL-10 and HGF plasmids was much improved, with 112 ± 39 mm Hg (vs. groups II and III; P < .01 each), paralleled by reduced vascular and bronchial rejection (group I vs. groups II and III, P < .021 each). Sequential overexpression of anti-inflammatory cytokine IL-10, followed by sequential and overlapping HGF overexpression on day 5, preserves lung function and reduces acute lung allograft rejection up to day 15 post transplant as compared to prolonged IL-10 overexpression alone.

Computational Design and Experimental Discovery of an Anti-estrogenic Peptide Derived from Alpha-Fetoprotein

Breast cancer is the most common cancer among women, and tamoxifen is the preferred drug for estrogen receptor-positive breast cancer treatment. Many of these cancers are intrinsically resistant to tamoxifen or acquire resistance during treatment. Consequently, there is an ongoing need for breast cancer drugs that have different molecular targets. Previous work has shown that 8-mer and cyclic 9-mer peptides inhibit breast cancer in mouse and rat models, interacting with an unsolved receptor, while peptides smaller than eight amino acids did not. We show that the use of replica exchange molecular dynamics predicts the structure and dynamics of active peptides, leading to the discovery of smaller peptides with full biological activity. Simulations identified smaller peptide analogues with the same conserved reverse turn demonstrated in the larger peptides. These analogues were synthesized and shown to inhibit estrogen-dependent cell growth in a mouse uterine growth assay, a test showing reliable correlation with human breast cancer inhibition.

Friendship as a relationship infiltration tactic during human mate poaching.

Previous research has characterized human mate poaching as a prevalent alternative mating strategy that entails risks and costs typically not present during general romantic courtship and attraction. This study is the first to experimentally investigate friendship between a poacher and his/her target as a risk mitigation tactic. Participants (N = 382) read a vignette that differed by whether the poacher was male/female and whether the poacher and poached were friends/acquaintances. Participants assessed the likelihood of the poacher being successful and incurring costs. They also rated the poacher and poached on several personality and mate characteristics. Results revealed that friendship increased the perceived likelihood of success of a mate poaching attempt and decreased the perceived likelihood of several risks typically associated with mate poaching. However, friend-poachers were rated less favorably than acquaintance-poachers across measures of warmth, nurturance, and friendliness. These findings are interpreted using an evolutionary perspective. This study complements and builds upon previous findings and is the first experimental investigation of tactics poachers may use to mitigate risks inherent in mate poaching.

Friendship as a Relationship Infiltration Tactic during Human Mate Poaching

Previous research has characterized human mate poaching as a prevalent alternative mating strategy that entails risks and costs typically not present during general romantic courtship and attraction. This study is the first to experimentally investigate friendship between a poacher and his/her target as a risk mitigation tactic. Participants (N = 382) read a vignette that differed by whether the poacher was male/female and whether the poacher and poached were friends/acquaintances. Participants assessed the likelihood of the poacher being successful and incurring costs. They also rated the poacher and poached on several personality and mate characteristics. Results revealed that friendship increased the perceived likelihood of success of a mate poaching attempt and decreased the perceived likelihood of several risks typically associated with mate poaching. However, friend-poachers were rated less favorably than acquaintance-poachers across measures of warmth, nurturance, and friendliness. These findings are interpreted using an evolutionary perspective. This study complements and builds upon previous findings and is the first experimental investigation of tactics poachers may use to mitigate risks inherent in mate poaching.

Feature Versus Spatial Strategies by Orangutans (Pongo abelii) and Human Children (Homo sapiens) in a Cross-Dimensional Task

Despite the fact that photographic stimuli are used across experimental contexts with both human and nonhuman subjects, the nature of individuals' perceptions of these stimuli is still not well understood. In the present experiments, we tested whether three orangutans and 36 human children could use photographic information presented on a computer screen to solve a perceptually corresponding problem in the physical domain. Furthermore, we tested the cues that aided in this process by pitting featural information against spatial position in a series of probe trials. We found that many of the children and one orangutan were successfully able to use the information cross-dimensionally; however, the other two orangutans and almost a quarter of the children failed to acquire the task. Species differences emerged with respect to ease of task acquisition. More striking, however, were the differences in cues that participants used to solve the task: Whereas the orangutan used a spatial strategy, the majority of children used a feature one. Possible reasons for these differences are discussed from both evolutionary and developmental perspectives. The novel results found here underscore the need for further testing in this area to design appropriate experimental paradigms in future comparative research settings.