Biologically active fibers based on chitosan-coated lyocell fibers

The possibilities of obtaining biologically active cellulose–chitosan fibers were examined. An effective two-stage method was developed. The first stage involves the formation of dialdehyde cellulose by the potassium periodate oxidation of lyocell fibers, which is able to form Schiff’s base with chitosan. In the second stage, chitosan-coated lyocell fibers were prepared by subsequent treatment of oxidized lyocell fibers with a solution of chitosan in aqueous acetic acid. The impact of this two-stage protocol on the chemical and physical properties of lyocell fibers was evaluated by determining carbonyl group content, fineness and tensile strength of fibers, as well as chitosan content in the composite cellulose–chitosan fibers. Antibacterial activity of the chitosan-coated lyocell fibers against different pathogenens: Staphylococcus aureus and Escherichia coli, was confirmed in vitro experiments.     

Papermaking fibers

True paper, in the technical sense of the term, was first made in China in 105a.d. from the bast fibers of paper mulberry and probably also from bamboo. For many centuries old rags, principally cotton or linen, supplied the papermakers with raw material In modern times, sprucewood fibers have long been outstanding for papermaking. In recent decades, however, the spruces have been equalled, if not surpassed, in tonnage used, by various species of pine, especially the southern yellow pines. Of secondary importance have been the fibers of dozens of other species.     

Biogenesis of plant fibers

The fiber (in terms of plant biology) is an individual cell characterized by spindle shape, length of up to several centimeters, well developed cell wall, and mechanical function. The review summarizes different, sometimes contradictory view points about duration, segregation and mechanisms of realization of individual stages of fiber biogenesis. Initiation and coordinated and intrusive growth are considered, as well as formation of secondary cell wall, including its gelatinous layers, and senescence. Biogenesis of fibers ontogenetically related to various tissues has been analyzed and the data about marker stage-specific characters of these cells. The data summarized in this review will allow not only deeper understanding the development of cells with such unique characters, but also interpret the growth mechanisms for much more cell types, in which it is more difficult to identify individual stages of biogenesis than in the sclerenchyma fibers.     

Biogenesis of plant fibers

The fiber (in terms of plant biology) is an individual cells characterized by spindle shape, length of up to several centimeters, well developed cell wall, and mechanical function. The review summarizes different, sometimes contradictory view points about duration, segregation and mechanisms of realization of individual stages of fiber biogenesis. Initiation and coordinated and intrusive growth are considered, as well as formation of secondary cell wall, including its gelatinous layers, and senescence. Biogenesis of fibers ontogenetically related to various tissues has been analyzed and the data about marker stage-specific characters of these cells. The data summarized in this review willow not only deeper understanding the development of cells with such unique characters, but also interpret the growth mechanisms for much more cell types, in which it is more difficult to identify individual stages of biogenesis than in the sclerenchyme fibers.     

Regenerating retinal fibers display error-free homing along undamaged normal fibers

After crushing one optic nerve in a bony fish, retinal fibers regenerate to both tecta. Anterograde labelling indicates that the ipsilaterally regenerating fibers have a rather straight growth, apparently along the undamaged fibers of the contralateral retina. In contrast, the contralaterally regenerating fibers deviate widely from a straight course. Retrograde labelling shows a mirror-symmetric distribution of regenerated ipsilateral and resident contralateral ganglion cells in a comparable annulus. In contrast, ganglion cells in the regenerated contralateral retina show no topological order after comparable small Dil applications to the ventrolateral tectum. These data suggest that regenerating fibers can orient on the undisturbed, contralateral fibers. © 1993 John Wiley & Sons, Inc.     

Olfactory nerve fibers

Cross sections of olfactory nerves present a unique appearance. They indicate the presence of large numbers of very small nerve fibers, with a modal diameter of about 0.2 µ and a narrow range for their size variation. From one side of the nasal septum of a pig the yield of fibers was estimated at 6,000,000; the number arising from the turbinates would be considerably larger. The fibers are attached to the membranes of the Schwann sheaths in large bundles through mesaxons longer and more branched than those that have been seen in other nerves. Continuity of the axons between the nerves and the bipolar cells was traced in an examination of the olfactory mucous membrane; and the indication of a one-to-one relationship between cells and axons was reinforced by a comparative count. After the axons leave the bipolar cells they become incased in the central projections of the sustentacular cells. Where the latter come into contact with the basal cells the axons emerge to push back the plasma membranes of the basal cells in the first step in acquiring their nerve sheaths. Later steps are described. When the axons are delivered by the basal cells to the collecting Schwann tubes, they are already aggregated into small bundles with sheaths fundamentally the same as those they will possess until they are delivered to the glia in the olfactory bulb. Some of the aspects of the cytology of the bipolar cells and adjoining sustentacular cells are described. A survey of the physiological properties of olfactory nerve fibers was made in some experiments on the olfactory nerve of the pike. Almost all of the action potential is encompassed within a single elevation, manifesting at its front a conduction velocity of 0.2 m./sec. For a comparison, the last elevation in the C action potential in the sciatic nerve of the frog is cited as an example of conduction at the same velocity. Though expressed through long time constants, the properties of the pike olfactory fibers conform to the generalized schema for properties of vertebrate nerve fibers. This conformity signalizes that they differ from the exceptional properties of the unmedullated fibers of dorsal root origin. An afferent function for unmedullated nerve fibers does not imply that the fibers concerned are alike in their physiological properties.     

Plasticity of skeletal muscle: regenerating fibers adapt more rapidly than surviving fibers

The properties of mammalian skeletal muscle demonstrate a high degree of structural and functional plasticity as evidenced by their adaptability to an atypical site after cross-transplantation and to atypical innervation after cross-innervation. We tested the hypothesis that, regardless of fiber type, skeletal muscles composed of regenerating fibers adapt more readily than muscles composed of surviving fibers when placed in an atypical site with atypical innervation. Fast muscles of rats were autografted into the site of slow muscles or vice versa with the donor muscle innervated by the motor nerve to the recipient site. Surviving fibers in donor muscles were obtained by grafting with vasculature intact (vascularized muscle graft), and regenerating fibers were obtained by grafting with vasculature severed (free muscle graft). Our hypothesis was supported because 60 days after grafting, transposed muscles with surviving fibers demonstrated only a slight change from the contractile properties and fiber typing of donor muscles, whereas transplanted muscles with regenerating fibers demonstrated almost complete change to those of the muscle formerly in the atypical site.     

The effect of pyrophosphate on the rigor fibers of rabbit m. psoas fibers

The effect of MgPPi on the rigor force of glycerinated fibres in the range of ionic strength 75-250 mM at two temperatures 18 degrees and 5 degrees C was studied. At 18 degrees C the maximum of this effect was above the range of average ionic strength. At 5 degrees C the greatest effect of MgPPi was observed at low ionic strength.     

Metabolic properties of muscle fibers

Mammalian skeletal muscles are composed of slow (type I) and fast (type II) twitch fibers, which, as reflected by their enzyme activity patterns, are characterized by specific metabolic properties. Type I fibers are always "oxidative" but nevertheless form a spectrum. Type II fibers likewise form a spectrum but display a wider range with "oxidative" and "glycolytic" extremes. As a result, type I and type II fibers can be classified independently of myofibrillar ATPase histochemistry by their specific enzyme activity profiles. In this context, activity ratios between enzymes of anaerobic and aerobic pathways can be used as discriminative parameters. Similarly, specific ratios of enzymes catalyzing unidirectional reactions in hexose metabolism (hexokinase, phosphofructokinase, fructose-1,6-bisphosphatase) separate the two fiber populations. The histochemically defined IIA and IIB subtypes cannot be separated into distinct metabolic groups. In view of the continuum of metabolic properties, skeletal muscle is an extremely heterogeneous tissue in which each fiber represents a separate metabolic compartment.     

Bio-catalyzed coloration of cellulose fibers

Cotton fabrics were dyed with dyes generated in situ by laccase-catalyzed oxidative coupling of the colorless 2,5-diaminobenzenesulfonic acid (2,5-DABSA) and 1-hydroxyphenol (catechol). The enzymatic oxidation of the dye intermediates led to cross-coupling reaction products when the reaction was conducted with an excess of catechol. At least fourfold excess of catechol was necessary to achieve satisfactory dye fixation on cotton. Formation of the same colored product using either an equimolar ratio of the reagents or tenfold excess of catechol was observed. Most probably, homo-molecular reactions predominate over the cross-coupling at equimolar ratio of the precursors, while with an excess of catechol, the cross-coupling occurs in higher yield. The reaction was followed using UV-Vis spectroscopy, HPLC, FTIR and MALDI-TOF MS. A reaction pathway for laccase-induced cross-coupling of catechol and 2,5-DABSA yielding a major colored product was proposed.