Occupational asthma associated with bleached chlorine-free cellulose dust in a sanitary pad production plant.

BACKGROUND: Cellulose is an insoluble plant polysaccharide produced from soft-wood pulp. Although chronic respiratory effects associated with high cellulose-based dust levels have been previously described, occupational asthma has not. A 37 year old machine operator in a sanitary pad production factory presented with new-onset work-related asthma symptoms for two years. METHODS: The worker underwent clinical, pulmonological and immunological (skin prick tests, serum specific IgE determinations) evaluation using standardised procedures. The cellulose product was subjected to scanning electron microscopy (SEM) examination. A specific inhalation challenge test performed with the cellulose product ensured that dust concentrations were kept below 5 mg/m3 . RESULTS: The subject was not atopic and did not have elevated IgE to pine wood or xylanase. The cellulose product appeared to be free of protein contaminants on SEM. The Work Effect Index computed on serial PEF recordings was elevated (WEI = 3.8).Specific inhalational challenge with the cellulose product dust revealed a late bronchial response (39% drop in FEV1 at 3 hours post challenge). CONCLUSION: This is the first reported case of occupational asthma to a cellulose fibre product. A non-specific immune reaction or irritant response seems likely. These fibres may therefore not be biologically inert. The occupational exposure limit of 10 mg/m3 generally used for cellulose dust appears to be non-protective.

Synthesis and characterization of water-soluble silk peptides and recombinant silk protein containing polyalanine, the integrin binding site, and two glutamic acids at each terminal site as a possible candidate for use in bone repair materials.

The recombinant proteins [EE(A)12EETGRGDSPAAS]n (n = 5,10) were prepared as a potential scaffold material for bone repair. The construct was based on Antheraea perni silk fibroin to which cells adhere well and combined poly(alanine), the integrin binding site TGRGDSPA, and a pair of glutamic acids (E2) at both the N- and C-terminal sites to render the construct water-soluble and with the hope that it might enhance mineralization with hydroxyapatite. Initially, two peptides E2(A)nE2TGRGDSPAE2(A)nE2 (n = 6, 12) were prepared by solid state synthesis to examine the effect of size on conformation and on cell binding. The larger peptide bound osteoblasts more readily and had a higher helix content than the smaller one. Titration of the side chain COO(-) to COOH of the E2 and D units in the peptide was monitored by solution NMR. On the basis of these results, we produced the related recombinant His tagged protein [EE(A)12EETGRGDSPAAS]n (n = 5,10) by expression in Escherichia coli . The solution NMR spectra of the recombinant protein indicated that the poly(alanine) regions are helical, and one E2 unit is helical and the other is a random coil. A molecular dynamics simulation of the protein supports these conclusions from NMR. We showed that the recombinant protein, especially, [EE(A)12EETGRGDSPAAS]10 has some of the properties required for bone tissue engineering scaffold including insolubility, and evidence of enhanced cell binding through focal adhesions, and enhanced osteogenic expression of osteoblast-like cells bound to it, and has potential for use as a bone repair material.

Synchrotron FTIR microspectroscopy of single natural silk fibers.

Synchrotron FTIR (S-FTIR) microspectroscopy was used to monitor the silk protein conformation in a range of single natural silk fibers (domestic and wild silkworm and spider dragline silk). With the selection of suitable aperture size, we obtained high-resolution S-FTIR spectra capable of semiquantitative analysis of protein secondary structures. For the first time, we have determined from S-FTIR the ß-sheet content in a range of natural single silk fibers, 28 ± 4, 23 ± 2, and 17 ± 4% in Bombyx mori, Antheraea pernyi, and Nephila edulis silks, respectively. The trend of ß-sheet content in different silk fibers from the current study accords quite well with published data determined by XRD, Raman, and (13)C NMR. Our results indicate that the S-FTIR microspectroscopy method has considerable potential for the study of single natural silk fibers.

Proteomic analysis of polymeric salivary mucins: no evidence for MUC19 in human saliva.

MUC5B is the predominant polymeric mucin in human saliva [Thornton, Khan, Mehrotra, Howard, Veerman, Packer and Sheehan (1999) Glycobiology 9, 293-302], where it contributes to oral cavity hydration and protection. More recently, the gene for another putative polymeric mucin, MUC19, has been shown to be expressed in human salivary glands [Chen, Zhao, Kalaslavadi, Hamati, Nehrke, Le, Ann and Wu (2004) Am. J. Respir. Cell Mol. Biol. 30, 155-165]. However, to date, the MUC19 mucin has not been isolated from human saliva. Our aim was therefore to purify and characterize the MUC19 glycoprotein from human saliva. Saliva was solubilized in 4 M guanidinium chloride and the high-density mucins were purified by density-gradient centrifugation. The presence of MUC19 was investigated using tandem MS of tryptic peptides derived from this mucin preparation. Using this approach, we found multiple MUC5B-derived tryptic peptides, but were unable to detect any putative MUC19 peptides. These results suggest that MUC19 is not a major component in human saliva. In contrast, using the same experimental approach, we identified Muc19 and Muc5b glycoproteins in horse saliva. Moreover, we also identified Muc19 from pig, cow and rat saliva; the saliva of cow and rat also contained Muc5b; however, due to the lack of pig Muc5b genomic sequence data, we were unable to identify Muc5b in pig saliva. Our results suggest that unlike human saliva, which contains MUC5B, cow, horse and rat saliva are a heterogeneous mixture of Muc5b and Muc19. The functional consequence of these species differences remains to be elucidated.

The Human In Vivo Biomolecule Corona onto PEGylated Liposomes: A Proof-of-Concept Clinical Study.

The self-assembled layered adsorption of proteins onto nanoparticle (NP) surfaces, once in contact with biological fluids, is termed the "protein corona" and it is gradually seen as a determinant factor for the overall biological behavior of NPs. Here, the previously unreported in vivo protein corona formed in human systemic circulation is described. The human-derived protein corona formed onto PEGylated doxorubicin-encapsulated liposomes (Caelyx) is thoroughly characterized following the recovery of liposomes from the blood circulation of ovarian carcinoma patients. In agreement with previous investigations in mice, the in vivo corona is found to be molecularly richer in comparison to its counterpart ex vivo corona. The intravenously infused liposomes are able to scavenge the blood pool and surface-capture low-molecular-weight, low-abundance plasma proteins that cannot be detected by conventional plasma proteomic analysis. This study describes the previously elusive or postulated formation of protein corona around nanoparticles in vivo in humans and illustrates that it can potentially be used as a novel tool to analyze the blood circulation proteome.

Psychosocial stress reactivity is associated with decreased whole-brain network efficiency and increased amygdala centrality.

Cognitive and emotional functions are supported by the coordinated activity of a distributed network of brain regions. This coordinated activity may be disrupted by psychosocial stress, resulting in the dysfunction of cognitive and emotional processes. Graph theory is a mathematical approach to assess coordinated brain activity that can estimate the efficiency of information flow and determine the centrality of brain regions within a larger distributed neural network. However, limited research has applied graph-theory techniques to the study of stress. Advancing our understanding of the impact stress has on global brain networks may provide new insight into factors that influence individual differences in stress susceptibility. Therefore, the present study examined the brain connectivity of participants that completed the Montreal Imaging Stress Task (Goodman et al., 2016; Wheelock et al., 2016). Salivary cortisol, heart rate, skin conductance response, and self-reported stress served as indices of stress, and trait anxiety served as an index of participant's disposition toward negative affectivity. Psychosocial stress was associated with a decrease in the efficiency of the flow of information within the brain. Further, the centrality of brain regions that mediate emotion regulation processes (i.e., hippocampus, ventral prefrontal cortex, and cingulate cortex) decreased during stress exposure. Interestingly, individual differences in cortisol reactivity were negatively correlated with the efficiency of information flow within this network, whereas cortisol reactivity was positively correlated with the centrality of the amygdala within the network. These findings suggest that stress reduces the efficiency of information transfer and leaves the function of brain regions that regulate the stress response vulnerable to disruption. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Anticipatory stress associated with functional magnetic resonance imaging: Implications for psychosocial stress research.

Stress tasks performed during functional magnetic resonance imaging (fMRI) elicit a relatively small cortisol response compared to stress tasks completed in a traditional behavioral laboratory, which may be due to apprehension of fMRI that elicits an anticipatory stress response. The present study investigated whether anticipatory stress is greater prior to research completed in an MRI environment than in a traditional behavioral laboratory. Anticipatory stress (indexed by cortisol) was greater prior to testing in the MRI environment than traditional behavioral laboratory. Furthermore, anticipation of fMRI elicited a cortisol response commensurate with the response to the stress task in the behavioral laboratory. However, in the MRI environment, post-stress cortisol was significantly lower than baseline cortisol. Taken together, these findings suggest the stress elicited by anticipation of fMRI may lead to acute elevations in cortisol prior to scanning, which may in turn disrupt the cortisol response to stress tasks performed during scanning.

Emotion socialization as a predictor of physiological and psychological responses to stress.

Reactivity patterns to acute stress are important indicators of physical and mental health. However, the relationships between emotion socialization and stress responses are not well understood. This study aimed to examine whether parental responses to negative emotions predicted physiological and psychological responses to acute stress in late adolescence and emerging adulthood, and whether these relationships varied by gender and ethnicity. Participants were 973 individuals (mean age=19.20years; 50% male; 63% African American, 34% European American) who reported on parental emotion socialization. Participants completed a standardized social stress test (the Trier Social Stress Test; TSST). Heart rate, blood pressure and salivary samples were assessed from baseline throughout the task and during recovery period. Psychological responses to stress were measured immediately after the TSST. Unsupportive parental responses to children's negative emotions were associated with blunted cortisol reactivity and greater negative emotions to a psychosocial stress task in females and African American youth, whereas supportive parental responses predicted greater cortisol reactivity and lower negative emotions to stress in European American youth, as well as less negative emotions in males. However, parental responses to negative emotions did not predict heart rate or SBP reactivity to the TSST. Findings suggest that parental emotion socialization may be an important factor influencing HPA axis reactivity and psychological responses to stress, with important differences across gender and ethnic youth subgroups.

The hippocampal response to psychosocial stress varies with salivary uric acid level.

Uric acid is a naturally occurring, endogenous compound that impacts mental health. In particular, uric acid levels are associated with emotion-related psychopathology (e.g., anxiety and depression). Therefore, understanding uric acid's impact on the brain would provide valuable new knowledge regarding neural mechanisms that mediate the relationship between uric acid and mental health. Brain regions including the prefrontal cortex, amygdala, and hippocampus underlie stress reactivity and emotion regulation. Thus, uric acid may impact emotion by modifying the function of these brain regions. The present study used functional magnetic resonance imaging (fMRI) during a psychosocial stress task to investigate the relationship between baseline uric acid levels (in saliva) and brain function. Results demonstrate that activity within the bilateral hippocampal complex varied with uric acid concentrations. Specifically, activity within the hippocampus and surrounding cortex increased as a function of uric acid level. The current findings suggest that uric acid levels modulate stress-related hippocampal activity. Given that the hippocampus has been implicated in emotion regulation during psychosocial stress, the present findings offer a potential mechanism by which uric acid impacts mental health.

A proteomic approach reveals integrin activation state-dependent control of microtubule cortical targeting.

Integrin activation, which is regulated by allosteric changes in receptor conformation, enables cellular responses to the chemical, mechanical and topological features of the extracellular microenvironment. A global view of how activation state converts the molecular composition of the region proximal to integrins into functional readouts is, however, lacking. Here, using conformation-specific monoclonal antibodies, we report the isolation of integrin activation state-dependent complexes and their characterization by mass spectrometry. Quantitative comparisons, integrating network, clustering, pathway and image analyses, define multiple functional protein modules enriched in a conformation-specific manner. Notably, active integrin complexes are specifically enriched for proteins associated with microtubule-based functions. Visualization of microtubules on micropatterned surfaces and live cell imaging demonstrate that active integrins establish an environment that stabilizes microtubules at the cell periphery. These data provide a resource for the interrogation of the global molecular connections that link integrin activation to adhesion signalling.

Modulation of cell growth on exposure to silkworm and spider silk fibers.

Recent years have seen an increased interest in the use of natural and modified silks for tissue engineering. Despite longstanding concerns regarding the biocompatibility of silk sutures, only a few studies have been carried out to investigate the biocompatibility of natural silk fibers. Here, we report an in vitro assessment of the effect of nonmodified, degummed silks on cells. We describe the effects of degummed silk fibers as well as extracted sericin on cell metabolism and proliferation. Endothelial cells directly exposed to native degummed Bombyx mori and Antheraea pernyi silks showed lower rates of proliferation and metabolism than nonexposed cells. A similar but milder effect was observed for cells in direct contact with Nephila edulis egg sack fibers. Sericin and silk-conditioned medium had no negative effect on cell proliferation except in medium supplemented with 5% bovine serum prior to conditioning with A. pernyi silk. The toxicity of A. pernyi was negligible after thorough enzymatic treatment of the fibers with trypsin. It is, therefore, proposed that A. pernyi silk contain one or more cytotoxic components, which need to be removed prior to medical use.

Oxidation of glycerol using gold-palladium alloy-supported nanocrystals.

The use of bio-renewable resources for the generation of materials and chemicals continues to attract significant research attention. Glycerol, a by-product from biodiesel manufacture, is a highly functionalised renewable raw material, and in this paper the oxidation of glycerol in the presence of base using supported gold, palladium and gold-palladium alloys is described and discussed. Two supports, TiO(2) and carbon, and two preparation methods, wet impregnation and sol-immobilisation, are compared and contrasted. For the monometallic catalysts prepared by impregnation similar activities are observed for Au and Pd, but the carbon-supported monometallic catalysts are more active than those on TiO(2). Glycerate is the major product and lesser amounts of tartronate, glycolate, oxalate and formate are observed, suggesting a sequential oxidation pathway. Combining the gold and palladium as supported alloy nanocrystals leads to a significant enhancement in catalyst activity and the TiO(2)-supported catalysts are significantly more active for the impregnated catalysts. The use of a sol-immobilisation preparation method as compared to impregnation leads to the highest activity alloy catalysts and the origins of these activity trends are discussed.

Effect of pacifier use on mandibular position in preterm infants.

AIM: It has been hypothesized that the association of pacifier use with reduced risk of sudden infant death is mediated by forward movement of the mandible and tongue that helps open the upper airway. Our aim was to examine whether the mandible is moved forward when an infant is sucking on a pacifier, and if so, whether the mandible remains advanced after the pacifier is removed. METHODS: In sixty clinically stable premature infants (corrected gestation age 36.5 +/- 0.3 weeks, mean +/- SEM) the distance from each ear where the pinna met the cheek to the most prominent point of the chin was measured bilaterally, and the average was used as an index of mandibular position. Mandibular position was determined before and after allowing the infants to suck on a pacifier for 10-15 min, and after removing the pacifier. RESULTS: There was a significant forward movement of the mandible when the infants were sucking on the pacifier (59.5 +/- 0.7 vs. 58.6 +/- 0.7 mm, p = 0.001), with no significant change after the pacifier was removed. CONCLUSIONS: Pacifier use in preterm infants was associated with a small significant forward displacement of the jaw. These data suggest that pacifier use may help protect the upper airway.

The correlation between immediate radiolucent lines and early implant migration in cemented acetabular components.

Periacetabular radiolucent lines (RLLs) on postoperative radiographs have been associated with early loosening of the acetabular component. It has also been shown that excessive migration of an implant corresponds to an increased incidence of later clinical failure. This study relates RLLs on anterior-posterior hip radiographs taken 10 days and 6 months postoperatively to implant migration detected by roentgen stereophotogrammetric analysis. We have shown that RLLs in DeLee and Charnley zone III in the first week postoperatively as well as at 6 months are positively and significantly (P < .05) associated with migration detected by roentgen stereophotogrammetric analysis. No significant association was found for zone I or II at either 10 days or at 6 months. Considering the limitations in observing RLLs, their presence in zone III appears to reflect on the mechanical stability of the acetabular cup from the beginning. This indicates that zone III, which represents the inferomedial aspect of the acetabulum, might have to receive special attention when preparing the acetabulum and implanting the acetabular cup.

Synthesis and characterization of multiblock copolymers based on spider dragline silk proteins.

Spider dragline silk with its superlative tensile properties provides an ideal system to study the relationship between morphology and mechanical properties of a structural protein. Accordingly, we synthesized two hybrid multiblock copolymers by condensing poly(alanine) [(Ala)(5)] blocks of the structural proteins (spidroin MaSp1 and MaSp2) of spider dragline silk with different oligomers of isoprene (2200 and 5000 Da) having reactive end groups. The synthetic multiblock polymer displayed similar secondary structure to that of natural spidroin, the peptide segment forming a beta-sheet structure. These multiblock polymers showed a significant solubility in the component solvents. Moreover, the copolymer which contains the short polyisoprene segment would aggregate into a micellar-like structure, as observed by TEM.

Structure of model peptides based on Nephila clavipes dragline silk spidroin (MaSp1) studied by 13C cross polarization/magic angle spinning NMR.

To obtain detailed structural information for spider dragline spidroin (MaSp1), we prepared three versions of the consensus peptide GGLGGQGAGAAAAAAGGAGQGGYGGLGSQGAGR labeled with 13C at six different sites. The 13C CP/MAS NMR spectra were observed after treating the peptides with different reagents known to alter silk protein conformations. The conformation-dependent 13C NMR chemical shifts and peak deconvolution were used to determine the local structure and the fractional compositions of the conformations, respectively. After trifluoroacetic acid (solvent)/diethyl ether (coagulant) treatment, the N-terminal region of poly-Ala (PLA) sequence, Ala8 and Ala10, adopted predominantly the alpha-helix with a substantial amount of beta-sheet. The central region, Ala15, Ala18, and Leu26, and C-terminal region, Ala31, of the peptide were dominated by either 3(1)-helix or alpha-helix. There was no indication of beta-sheet, although peak broadening indicates that the torsion angle distribution is relatively large. After 9 M LiBr/dialysis treatment, three kinds of conformation, beta-sheet, random coil, and 3(1)-helix, appeared, in almost equal amounts of beta-sheet and random coil conformations for Ala8 and Ala10 residues and distorted 3(1)-helix at the central region of the peptide. In contrast, after formic acid/methanol and 8 M urea/acetonitrile treatments, all of the local structure tends to beta-sheet, although small amounts of random coil are also observed. The peak pattern of the Ala Cbeta carbon after 8 M urea/acetonitrile treatment is similar to the corresponding patterns of silk fiber from Bombyx mori and Samia cynthia ricini. We also synthesized a longer 13C-labeled peptide containing two PLA blocks and three Gly-rich blocks. After 8 M urea/acetonitrile treatment, the conformation pattern was closely similar to that of the shorter peptide.

Biological liquid crystal elastomers.

Liquid crystal elastomers (LCEs) have recently been described as a new class of matter. Here we review the evidence for the novel conclusion that the fibrillar collagens and the dragline silks of orb web spiders belong to this remarkable class of materials. Unlike conventional rubbers, LCEs are ordered, rather than disordered, at rest. The identification of these biopolymers as LCEs may have a predictive value. It may explain how collagens and spider dragline silks are assembled. It may provide a detailed explanation for their mechanical properties, accounting for the variation between different members of the collagen family and between the draglines in different spider species. It may provide a basis for the design of biomimetic collagen and dragline silk analogues by genetic engineering, peptide- or classical polymer synthesis. Biological LCEs may exhibit a range of exotic properties already identified in other members of this remarkable class of materials. In this paper, the possibility that other transversely banded fibrillar proteins are also LCEs is discussed.

Pharmacodynamic enhancement of the anti-platelet antibody fab abciximab by site-specific pegylation.

Monoclonal antibodies have been firmly established as human therapeutics. Their high affinity and specificity for target antigens minimize adverse reactions and their molecular size results in extended circulation times relative to small molecule pharmaceuticals. The ability to customize the pharmacokinetics in a rational manner can enhance the potential for these and other classes of biologicals. We have systematically studied the effect of site-specific pegylation of the Fab' fragment of the anti-GPIIb/IIIa, alphavbeta3 antibody c7E3. Regardless of the molecular weight of the PEG molecules, the intrinsic affinity of the resulting constructs remained unchanged. However, in functional assays measuring inhibition of platelet aggregation, the calculated IC50 values of the conjugates decreased with increasing molecular weight of the conjugated PEG. It was determined that the molecular size of the conjugates affects antigen accessibility and whereas high levels of binding to antigen molecules on cells with high antigen density can be demonstrated with the Fab fragment, comparable levels are not achievable with large molecular weight conjugates. In spite of the inability of the larger PEG constructs to achieve saturation binding, functional inhibition of platelet aggregation consistent with saturation binding was demonstrated and the increased molecular size of the conjugates led to predictably prolonged inhibition of platelet aggregation.