Induction of autoantibodies to glutamate in patients with Alzheimer’s disease

Autoantibodies to glutamate were found in blood plasma from patients with Alzheimer’s disease. The content of autoantibodies to glutamate in blood plasma from patients with moderate and severe dementia was 2-fold higher compared to patients with mild dementia. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 2, pp. 140–141, February, 2007     

Thermal dehydration treatment and glutaraldehyde cross-linking to increase the biostability of collagen–chitosan porous scaffolds used as dermal equivalent

A biodegradable scaffold for skin-tissue engineering was designed using collagen and chitosan, which are common materials for biomedical application. The scaffolds containing different amounts of chitosan were prepared by mixing the collagen and chitosan solutions followed by removal of the solvent using a freeze-drying method. The cross-linking treatment of these scaffolds was performed using the dehydrothermal treatment (DHT) method or glutaraldehyde (GA) to increase their biostability. The effect of the chitosan concentration and the cross-linking methods on the morphology of these scaffolds was studied by SEM. The water retention and the biodegradability in vitro of various collagen-chitosan scaffolds were investigated. Finally the biocompatibility of the collagen-chitosan (10 wt% chitosan) scaffold treated with different cross-linking methods was evaluated using a in vivo animal test. A mild inflammatory reaction could be detected in the early stages, and GA treatment can decrease the inflammatory reaction in a long-term implantation. After implantation for four weeks, all kinds of scaffolds, especially the GA-treated scaffolds (Col-GA) were filled with a large number of fibroblasts and were vascularized to a certain extent. These results suggest that the GA-treated scaffold has an increased biostability and excellent biocompatibility. It can be a potential candidate for skin-tissue engineering.     

Preferential recognition of epitopes on AGE–IgG by the autoantibodies in rheumatoid arthritis patients

Incubation of proteins with glucose lead to their non-enzymatic glycation ultimately resulting in the formation of advanced glycation end products (AGEs) in vivo. AGEs alter unique three dimensional structures of various plasma proteins such as IgG. The role of oxidative stress in the pathogenesis of rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease, is well established. In view of this, commercially available human IgG was glycated in vitro with physiological concentration of glucose (5 mM) and the possible involvement of glycated IgG (AGE–IgG) in RA was evaluated. The RA patients were divided into two groups on the basis of disease onset with respect to age: group I (early onset: 20–32 years) and group II (late onset: 36–54 years). AGE–IgG and oxidative stress levels were detected in RA patients and normal healthy individuals by nitroblue tetrazolium (NBT) assay and carbonyl content estimation respectively. Binding characteristics and specificity of RA antibodies were analyzed by enzyme-linked immunosorbent assay (ELISA). We observed preferential binding of RA antibodies to AGE–IgG in comparison to native IgG. Band shift assay further substantiated the enhanced recognition of AGE–IgG by RA antibodies. The results suggest that glycation of IgG results in the generation of neo-epitopes, making it a potential immunogen. Our findings project AGE–IgG as one of the factors for induction of circulating RA autoantibodies.     

Altered dermal fibroblast behavior in a collagen V haploinsufficient murine model of classic Ehlers–Danlos syndrome

Mutations in collagen V are associated with classic Ehlers–Danlos syndrome (EDS). A significant percentage of these mutations result in haploinsufficiency for collagen V. The purpose of this work was to determine if changes in collagen V expression are associated with altered dermal fibroblast behavior contributing to the poor wound healing response. A haploinsufficient Col5a1^+/? mouse model of EDS was utilized. In vivo wound healing studies demonstrated that mutant mice healed significantly slower than Col5a1^+/+ mice. The basis for this difference was examined in vitro using dermal fibroblast strains isolated from Col5a1^+/? and Col5a1^+/+ mice. Fibroblast proliferation was determined for each strain by counting cells at different time points after seeding as well as using the proliferation marker Ki-67. Fibroblast attachment to collagens I and III and fibronectin also was analyzed. In addition, in vitro scratch wounds were used to analyze fibroblast wound closure. Significantly decreased fibroblast proliferation was observed in Col5a1^+/? compared to Col5a1^+/+ fibroblasts. Our data indicate that the decreased fibroblast number was not due to apoptosis. Wildtype Col5a1^+/+ fibroblasts attached significantly better to components of the wound matrix (collagens I and III and fibronectin) than Col5a1^+/? fibroblasts. A significant difference in in vitro scratch wound closure rates also was observed. Col5a1^+/+ fibroblasts closed wounds in 22 h, while Col5a1^+/? fibroblasts demonstrated ~80% closure. There were significant differences in closure at all time points analyzed. Our data suggest that decreased fibroblast proliferation, extracellular matrix attachment, and migration contribute to the decreased wound healing response in classic EDS.     

The mechanical stress–strain properties of single electrospun collagen type I nanofibers

Knowledge of the mechanical properties of electrospun fibers is important for their successful application in tissue engineering, material composites, filtration and drug delivery. In particular, electrospun collagen has great potential for biomedical applications due to its biocompatibility and promotion of cell growth and adhesion. Using a combined atomic force microscopy (AFM)/optical microscopy technique, the single fiber mechanical properties of dry, electrospun collagen type I were determined. The fibers were electrospun from a 80 mg ml^?1 collagen solution in 1,1,1,3,3,3-hexafluro-2-propanol and collected on a striated surface suitable for lateral force manipulation by AFM. The small strain modulus, calculated from three-point bending analysis, was 2.82 GPa. The modulus showed significant softening as the strain increased. The average extensibility of the fibers was 33% of their initial length, and the average maximum stress (rupture stress) was 25 MPa. The fibers displayed significant energy loss and permanent deformations above 2% strain.     

Relevance of collagen piezoelectricity to “Wolff's Law”: A critical review

According to “Wolff's Law”, bone is deposited and reinforced at areas of greatest stress. From a clinical perspective, this “law” is supported by the strong association between bone density and physical activity. From a mechanistic standpoint, however, the law presents a challenge to scientists seeking to understand how osteocytes and osteoblasts sense the mechanical load. In the 1960s, collagen piezoelectricity was invoked as a potential mechanism by which osteocytes could detect areas of greater stress but piezoelectricity diminished in importance as more compelling mechanisms, such as streaming potential, were identified. In addition, accumulating evidence for the role of fluid-related shear stress in osteocyte's mechanosensory function has made piezoelectricity seemingly more obsolete in bone physiology. This review critically evaluates the role of collagen piezoelectricity (if any) in Wolff's Law—specifically, the evidence regarding its involvement in strain-generated potentials, existing alternate mechanisms, the present understanding of bone mechanosensation, and whether piezoelectricity serves an influential role within the context of this newly proposed mechanism. In addition to reviewing the literature, this review generates several hypotheses and proposes future research to fully address the relevance of piezoelectricity in bone physiology.     

Transforming growth factor β upregulates the integrin-mediated adhesion of human prostatic carcinoma cells to type I collagen

Prostate cancer frequently metastasizes to bone, and we propose that this process may be facilitated by the adhesion of metastatic cells to bone-derived type I collagen. We examined collagen receptor function and regulation in osteotropic PC-3 human prostatic carcinoma cells. PC-3 cell adhesion to immobilized human type I collagen was promoted by Mn and Mg ions and was RGD-independent. Antibodies directed against 1 or 2 integrin subunits inhibited adhesion to collagen by 90% and 53%, respectively, suggesting involvement of the 21 receptor. Anti-1 or anti-3 antibodies had no effect on adhesion. Flow cytometry and immunoprecipitation of [S]methionine-labeled cells demonstrated that 21 was the major collagen receptor expressed by PC-3 cells. The pretreatment of PC-3 cells with transforming growth factor-1 (TGF-1), a major bone-derived growth factor, caused a rapid (2 h) 2-fold increase in the de novo synthesis of 2 and 1 integrin subunits, and also increased by 2- to 3-fold the adhesion and spreading of PC-3 cells on collagen. We conclude that 21 is the major collagen receptor employed by PC-3 cells, and that 21 upregulation by TGF- is associated with an increased adhesion and spreading on collagen. The data suggest that exposure of metastatic PC-3 cells to the high levels of TGF- in bone may promote their ability to adhere to bone-derived collagen, which may thereby facilitate the localization of metastatic cells in the skeleton.     

Optimization of a natural collagen scaffold to aid cell–matrix penetration for urologic tissue engineering

The goal of this study was to fabricate a 3-dimensional (3-D) porous scaffold derived from bladder submucosa (BSM) and further recellularize the scaffold with human bladder cells for cell-based urethral tissue engineering. Fresh porcine BSM was soaked with peracetic acid (PAA) at different concentrations (0,1,3,5 and 10%) and then treated with Triton X-100 for decellularization. DNA content analysis showed that nuclear material was removed from the BSM scaffold. Treatment with 5% PAA led to high porosity on the surface of the matrix with retention of less cellular material and maintained about 75% of normal tensile strength. In 3-D dynamic culture, cells formed even multiple layers on the surface of matrix. Cells also penetrated deeper into the lamina propria of the matrix compared to untreated matrix. Immunocytochemical staining indicated that the grafted bladder cells expressed urothelial- and smooth muscle-specific markers both, in vitro and in vivo. This study demonstrates that decellularized/oxidized BSM possesses 3-D porosity for cell infiltration into the matrix. Further, cells seeded on decellularized/oxidized BSM and grown in dynamic culture, significantly promoted cell–matrix penetration in vitro and promoted cell growth in vivo. Scaffolds with such characteristics have potential applications in cell-based urological tissue engineering.     

Sensitivity of peripheral blood lymphocytes of pilots and astronauts to γ-radiation: Induction of double-stranded DNA breaks

The levels of DNA breaks before and after in vitro irradiation (1 Gy) of lymphocytes from 17 donors, 41 pilots, and 8 astronauts were studied by comet assay. Seventeen donors, 41 pilots, and 8 astronauts were examined. The flights augmented individual differences in the levels of DNA breaks in blood lymphocytes and in the severity of injuries inflicted by radiation exposure to lymphocyte DNA. Dispersions in the distribution of the initial levels of DNA breaks in pilots and astronauts differed significantly from the control according to Fisher’s F test. The dispersion of distribution of the levels of double-stranded DNA breaks after in vitro irradiation in the group of pilots also differed significantly from the control distribution. These results necessitate evaluation of individual sensitivity to the mission conditions during medical selection. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 10, pp. 404–407, October, 2007     

Adhesion of monocytes to type I collagen stimulates an APP-dependent proinflammatory signaling response and release of Aβ1-40

Background  

Amyloid precursor protein (APP) is a ubiquitously expressed cell surface protein reported to be involved in mediating cell-cell or cell-matrix interactions. Prior work has demonstrated that APP co-localizes with β1 integrin in different cell types.     

Predicting children's separation anxiety at age 6: The contributions of infant–mother attachment security,maternal sensitivity,and maternal separation anxiety

Abstract

The purpose of the present investigation was to examine the precursors and familial conditions which sustain school-aged children's separation anxiety. In a prospective, longitudinal study of 99 mother–child dyads, infancy measures of infant–mother attachment security, maternal separation anxiety, and maternal sensitivity were used to predict children's self-reported symptoms of separation anxiety at age 6. Insecurely attached children reported more separation anxiety than securely attached children. Insecure-ambivalent children reported marginally more separation anxiety than securely attached children, but not more than insecure-avoidant attached children. Regression analysis showed infant–mother attachment security and mother's sensitivity added uniquely to the prediction of children's separation anxiety, but mother's separation anxiety did not. Mediation tests show that the effect of mother's separation anxiety on children's separation anxiety may be mediated by maternal sensitivity. Research and clinical implications are discussed.     

Re-evaluation of the VIDAS® cytomegalovirus (CMV) IgG avidity assay: Determination of new cut-off values based on the study of kinetics of CMV–IgG maturation

BackgroundIn case of cytomegalovirus (CMV) infection, differentiation between primary and non-primary CMV infection can be of major importance for the correct management of pregnant women or immunocompromised patients. Besides CMV–IgM and IgG, CMV–IgG avidity measurement is now commonly used to distinguish primary from non-primary infection.ObjectiveTo re-evaluate the performance of the VIDAS CMV–IgG avidity assay in comparison with 2 other techniques (Architect Abbott and Liaison DiaSorin) and to study the kinetics of CMV–IgG avidity maturation.Study designA panel of 135 sequential samples collected from 31 patients with a proven primary infection (attested by very recent CMV–IgG seroconversion) was tested with VIDAS, Liaison and Architect CMV–IgG avidity assays. Moreover, 235 routinely collected samples, CMV–IgG and CMV–IgM positive, were analyzed with Liaison, VIDAS and an in-house CMV–IgG avidity assay.Results and conclusionsThe analysis of all the data allowed suggesting new VIDAS cut-off values of 0.40 for low avidity and 0.65 for high avidity, which significantly increase the test performance and enable better patient managements. Using these VIDAS new cut-off values, all of the 31 primary infections were correctly dated. Comparatively, 25 out of 31 were correctly dated with the Architect assay and 29 out of 31 with the Liaison assay. We also demonstrated that the VIDAS CMV–IgG avidity assay allows observing correctly the maturation of CMV–IgG avidity, which could be useful as an additional parameter for diagnosis of a recent CMV infection.     

Serum levels of IgG to the peptide of HCV1b core at positions 35–44 correlated with persistent infection,while levels of IgG to the peptide of NS5A at positions 2132–2140 correlated with better prognosis in HCV-infected patients

We previously reported that two IgG Abs to the hepatitis C virus (HCV), anti-core 35–44 (C35) and anti-NS5A 2132–2140 (NS5A2132), existed in the sera of the majority of patients with HCV infection. This study investigated if measuring the two Abs would facilitate the prediction of a patient’s prognosis. The serum levels of anti-C35 were found to correlate with persistent infection, while those of anti-NS5A2132 correlated with a better prognosis in HCV-infected patients. These results suggest that sequential measurement of the two Abs together may provide new information for the prediction of prognosis.     

In situ forming collagen–hyaluronic acid membrane structures: Mechanism of self-assembly and applications in regenerative medicine

Bioactive, in situ forming materials have the potential to complement minimally invasive surgical procedures and enhance tissue healing. For such biomaterials to be adopted in the clinic, they must be cost-effective, easily handled by the surgeon and have a history of biocompatibility. To this end, we report a novel and facile self-assembling strategy to create membranes and encapsulating structures using collagen and hyaluronic acid (HA). Unlike membranes built by layer-by-layer deposition of oppositely charged biomolecules, the collagen–HA membranes described here form a diffusion barrier upon electrostatic interaction of the oppositely charged biomolecules, which is further driven by osmotic pressure imbalances. The resulting membranes have a nanofibrous architecture, a thicknesses of 130 μm and a tensile modulus (0.59 ± 0.06 MPa) that can increase 7-fold using carbodiimide chemistry (4.42 ± 1.46 MPa). Collagen–HA membranes support mesenchymal stem cell proliferation and have a slow and steady protein release profile (7% at day 28), offering opportunities for targeted tissue regeneration. We demonstrate the capacity to encapsulate cells by injecting HA into the collagen solution, and enhance allograft and implant biocompatibility through a coating technique. This study describes a novel mechanism of collagen–HA membrane formation and provides the groundwork to apply these membranes in a variety of tissue engineering applications.     

Hypercapnic ventilatory response of anesthetized female rats subjected to neonatal maternal separation: Insight into the origins of panic attacks?

Neonatal maternal separation (NMS) is a form of stress that interferes with the regulation of the stress response, an effect that predisposes to the emergence of panic and anxiety related disorders. We previously showed that at adulthood, awake female (but not male) rats subjected to NMS show a hypercapnic ventilatory response (HCVR; 5% CO2) that is 63% greater than controls (Genest et al., 2007). To understand the mechanisms underlying the sex-specific effects of NMS on the ventilatory response to CO2, we used two different anesthetized female rat preparations to assess central CO2 chemosensitivity and contribution of sensory afferents (stretch receptors and peripheral chemoreceptors) that influence the HCVR. Data show that anesthesia eliminated the respiratory phenotype observed previously in awake females and CO2 chemosensitivity did not differ between groups. Finally, the assessment of the ovarian hormone levels across the oestrus cycle failed to reveal significant differences between groups. Since anesthesia did not affect the manifestation of NMS-related respiratory dysfunction in males (including the hypercapnic ventilatory response) (Kinkead et al., 2005; Dumont and Kinkead, 2010), we propose that the panic or anxiety induced by CO2 during wakefulness is responsible for enhancement of the HCVR in NMS females.