A histochemical study of the red and white muscle fibers Part III. Activity of the diphosphopyridine nucleotide diaphorase and triphosphopyridine nucleotide diaphorase in muscle fibers

From the histochemical study of DPN and TPN diaphorase on the striated muscles of the cats, the following results were obtained. 1. M. gastrocnemius, which belongs to the white muscle by naked eye, consists of three types of muscle fibers distinguished by the DPN diaphorase staining: namely, the small muscle fibers, i. e., the red muscle fibers show a moderate activity, being stained pink, while the large muscle fibers, i. e., the white muscle fibers show a low activity, being stained faint pink. The. third type of muscle fibers: namely, the medium fibers are stained pale pink and show the enzymatic activity intermediate between the red and white muscle fibers. 2. M. soleus, belonging to the red muscle by naked eye, consists of three types of fibers distinguished by the DPN-diaphorase staining, i. e., the red muscle fibers are stained pink, medium fibers pale pink, and a few white muscle fibers faint pink. The diameters of these three types of muscle fibers in M. soleus are almost the same. 3. From the staining pattern of TPN-diaphorase in M. gastrocnemius and M. soleus, the three types of muscle fibers can be distinguished by TPN-diaphorase activity, namely, the red muscle fibers show a high TPN-diaphorase activity, being stained purple, while, the white muscle fibers a low activity, being stained pale pink. The medium fibers are stained pink and show a moderate enzymatic activity intermediate between the red and white muscle fibers. 4. The TPN-diaphorase activity is higher than the DPN-diaphorase activity in the striated muscle, but it is less active than the TPN-diapborase activity in the kidney. However, the activity of DPN-diaphorase in the striated muscle is quite lower than that of the kidney.</p

Optical fiber coupling method and apparatus

Systems are described for coupling a pair of optical fibers to pass light between them, which enables a coupler to be easily made, and with simple equipment, while closely controlling the characteristics of the coupler. One method includes mounting a pair of optical fibers on a block having a large hole therein, so the fibers extend across the hole while lying adjacent and parallel to one another. The fibers are immersed in an etchant to reduce the thickness of cladding around the fiber core. The fibers are joined together by applying a liquid polymer so the polymer-air interface moves along the length of the fibers to bring the fibers together in a zipper-like manner, and to progressively lay a thin coating of the polymer on the fibers

Method of carbonizing polyacrylonitrile fibers

This invention relates to a method of carbonizing polyacrylonitrile fibers by exposing the fibers at an elevated temperature to an oxidizing atmosphere; then exposing the oxidized fibers to an atmosphere of an inert gas such as nitrogen containing a carbonaceous material such as acetylene. The fibers are preferably treated with an organic compound, for example benzoic acid, before the exposure to an oxidizing atmosphere. The invention also relates to the resulting fibers. The treated fibers have enhanced tensile strength

Using molecular mechanics to predict bulk material properties of fibronectin fibers

The structural proteins of the extracellular matrix (ECM) form fibers with finely tuned mechanical properties matched to the time scales of cell traction forces. Several proteins such as fibronectin (Fn) and fibrin undergo molecular conformational changes that extend the proteins and are believed to be a major contributor to the extensibility of bulk fibers. The dynamics of these conformational changes have been thoroughly explored since the advent of single molecule force spectroscopy and molecular dynamics simulations but remarkably, these data have not been rigorously applied to the understanding of the time dependent mechanics of bulk ECM fibers. Using measurements of protein density within fibers, we have examined the influence of dynamic molecular conformational changes and the intermolecular arrangement of Fn within fibers on the bulk mechanical properties of Fn fibers. Fibers were simulated as molecular strands with architectures that promote either equal or disparate molecular loading under conditions of constant extension rate. Measurements of protein concentration within micron scale fibers using deep ultraviolet transmission microscopy allowed the simulations to be scaled appropriately for comparison to in vitro measurements of fiber mechanics as well as providing estimates of fiber porosity and water content, suggesting Fn fibers are approximately 75% solute. Comparing the properties predicted by single molecule measurements to in vitro measurements of Fn fibers showed that domain unfolding is sufficient to predict the high extensibility and nonlinear stiffness of Fn fibers with surprising accuracy, with disparately loaded fibers providing the best fit to experiment. This work shows the promise of this microstructural modeling approach for understanding Fn fiber properties, which is generally applicable to other ECM fibers, and could be further expanded to tissue scale by incorporating these simulated fibers into three dimensional network models

Mechanical behavior of entangled fibers and entangled cross-linked fibers during compression

Entangled fibrous materials have been manufactured from different fibers: metallic fibers, glass fibers, and carbon fibers. Specimens have been produced with and without cross links between fibers. Cross-links have been achieved using epoxy spraying. The scope of this article is to analyze the mechanical behavior of these materials and to compare it with available models. The first part of this article deals with entangled fibrous materials without crosslink between fibers. Compression tests are detailed and test reproducibility is checked. In the second part, compression tests were performed on materials manufactured with cross-linked fibers. The specific mechanical behavior obtained is discussed

Factors Influencing Reinforcement of NR and EPDM Rubbers with Short Aramid Fibers

Among short fiber reinforced composites, those with rubbery matrices have gained great importance due to the advantages they have in processing and low cost, coupled with high strength. These composites combine the elastic behavior of rubbers with strength and stiffness of fibers. Reinforcement with short fibers offers additional features such as design flexibility, high modulus, tear strength, etc. The degree of reinforcement depends on parameters such as: the nature of the rubber matrix, the type of fibers, the concentration and orientation of fibers, fiber to rubber adhesion (generation of a strong interface), fiber length and aspect ratio of the fibers. In this research aramid fibers have been chosen because of their significantly higher modulus and strength, compared to other commercial fibers. Compounds based on NR and EPDM are prepared. Short aramid fibers with different kinds of surface treatments, standard finish and RFL-coating result in different rubber-fiber interfaces. The reinforcing effect of these short aramid fibers is characterized by mechanical and viscoelastic experiments, and by studying the fracture surfaces with microscopic techniques

Measuring forces between protein fibers by microscopy

We propose a general scheme for measuring the attraction between mechanically frustrated semiflexible fibers by measuring their thermal fluctuations and shape. We apply this analysis to a system of sickle hemoglobin (HbS) fibers that laterally attract one another. These fibers appear to “zip” together before reaching mechanical equilibrium due to the existence of cross-links into a dilute fiber network. We are also able to estimate the rigidities of the fibers. These rigidities are found to be consistent with sickle hemoglobin “single” fibers 20 nm in diameter, despite recent experiments indicating that fiber bundling sometimes occurs. Our estimate of the magnitude of the interfiber attraction for HbS fibers is in the range 8 ± 7 kBT/μm, or 4 ± 3 kBT/μm if the fibers are assumed, a priori to be single fibers (such an assumption is fully consistent with the data). This value is sufficient to bind the fibers, overcoming entropic effects, although extremely chemically weak. Our results are compared to models for the interfiber attraction that include depletion and van der Waals forces. This technique should also facilitate a similar analysis of other filamentous protein assembles in the future, including β-amyloid, actin, and tubulin

Study of some orthosymplectic Springer fibers

We decompose the fibers of the Springer resolution for the odd nilcone of the Lie superalgebra \osp(2n+1,2n) into locally closed subsets. We use this decomposition to prove that almost all fibers are connected. However, in contrast with the classical Springer fibers, we prove that the fibers can be disconnected and non equidimensional

Biotechnological modification and functionalisation of polyester surfaces

Synthetic fibers form an important part of the textile industry, the production of polyester alone surpassing that of cotton. A disadvantage of synthetic fibers is their low hydrophilicity. Polyester fibers are particularly hydrophobic. This affects the processability and functionalisation of the fibers. A relatively new and promising alternative is the use of enzymes in surface modification of synthetic fibers. Synthetic materials have generally been considered resistant to biological degradation; recent developments at different research groups demonstrate that enzymes are very well capable of hydrolysing synthetic materials

Proteomics of Cytochrome c Oxidase-Negative versus -Positive Muscle Fiber Sections in Mitochondrial Myopathy

The mosaic distribution of cytochrome c oxidase(+) (COX+) and COX - muscle fibers in mitochondrial disorders allows the sampling of fibers with compensated and decompensated mitochondrial function from the same individual. We apply laser capture microdissection to excise individual COX+ and COX- fibers from the biopsies of mitochondrial myopathy patients. Using mass spectrometry-based proteomics, we quantify >4,000 proteins per patient. While COX+ fibers show a higher expression of respiratory chain components, COX- fibers display protean adaptive responses, including upregulation of mitochondrial ribosomes, translation proteins, and chaperones. Upregulated proteins include C1QBP, required for mitoribosome formation and protein synthesis, and STOML2, which organizes cardiolipin-enriched microdomains and the assembly of respiratory supercomplexes. Factoring in fast/slow fiber type, COX (-) slow fibers show a compensatory upregulation of beta-oxidation, the AAA(+) protease AFG3L1, and the OPA1-dependent cristae remodeling program. These findings reveal compensatory mechanisms in muscle fibers struggling with energy shortage and metabolic stress