Packing of collagen molecules modified with 2-propanol.

X-ray diffraction data of collagen molecules modified with 2-propanol favour a quasi-hexagonal lateral packing over a quasi-tetragonal one.

Stress-induced molecular rearrangement in tendon collagen.

Tension-induced molecular rearrangements in wet native fibres of rat-tail tendons and human finger flexor tendons are registered with the help of time-resolved diffraction spectra using synchrotron radiation. The tension-induced increase of the 67 nm D period is combined with changes in the intensities of some orders of the meridional small angle reflection. Both effects are reversible when unloading the fibre, but are preserved when the load is held constant until the fibre tears. The increase in the D period is partly due to a sliding of the triple helices relative to each other and partly due to a stretching of the triple helices themselves. The sliding of the triple helices results in an alteration of the D stagger, leading to a change in the length of the gap and overlap regions, and to a stretching of the cross-linked telopeptides. This interpretation is supported by comparison with the relative intensities derived from a model with varying length of gap and overlap regions, as well as by comparison with model calculations that include the telopeptides.

Structural dynamic of native tendon collagen.

The dynamic behaviour of collagen fibrils is revealed by time-resolved X-ray investigations of native rat tail tendon fibres in tensile tests.

Transformation of the structure of collagen. A time-resolved analysis of mechanochemical processes using synchrotron radiation.

Mechanochemically induced molecular transformations of collagen fibres were analysed using time-resolved small-angle diffraction spectra and histomechanical measurements. In particular, the influence of aqueous and methanolic perchlorate solutions was examined. According to a transformation continuing from the periphery towards the centre, the macroscopic contraction that is completed less than five minutes after incubation with perchlorate is caused by peripherally transformed fibrils only, whereas the centrally situated fibrils first undergo an accordion-like folding, but after more than 20 minutes are transformed similarly. The triple-helical transformation is preceded by a structure-breaking effect on structural water that can be monitored in time-resolved diffraction spectra. The combined loss of meridional low-angle reflections and cross-striated fibrils in micrographs is irreversible. By dialysis of colloidally dissolved collagen against a solution of ATP, however, segment-long spacing aggregates are obtained. Under isometric conditions, an instantaneous transformation of intermittent regions leads to an increase in the long period of adjacent, still structured regions of the same fibril that is correlated with a delayed increase in tension in the fibre. Increase of tension under isometric conditions as well as the flow-properties of a fibre relaxed in perchlorate are interpreted in terms of the parallel sliding of subunits of varying lengths, which has been demonstrated by diffraction analysis.

The macromolecular structure of collagen in tendon fibres of dermatosparactic animals.

Small-angle x-ray diffraction spectra of dermatosparactic tendon collagen show a decreased intensity of the first order reflection. We interprete this finding to be due to the N-terminal propeptide which fills the intermolecular gap region partially.

Twisted fibrils are a structural principle in the assembly of interstitial collagens, chordae tendineae included.

X-ray diffraction analysis of connective tissue samples, which contain type I and type III collagen shows that twisted collagen fibrils are a general principle of assembly. The occurrence of twisted fibrils in native wet Chordae tendineae, skin and Aorta is combined with a shorter axial periodicity of about 65 nm. This shorter D period is shown to be directly related to the tilt of the molecules, which have to be curved to build-up twisted fibrils.

[The so-called filaments in lafora-bodies, corpora amylacea and Bielschowsky-bodies. Fasciolar substructures in accumulated intraplasmatic material of cellular dysmetabolies (author's transl)]. / Die sogenannten Filamente in Lafora-Körperchen, Corpora amylacea und Bielschowsky-Körperchen. Fascioläre Substrukturen in intraplasmatischen Speicherungsprodukten bei cellulären Dysmetabolien

Both the corpora amylacea and Lafora bodies have been described in the literature as filamentous structures. On electron microscopic examination they are often composed of ribbon-like fasciolar units. The ultrastructural appearance of these structures is discussed on the example of an amylopectin model. These fasciolar substructures are also encountered in Bielschowsky bodies and are then considered to be a sign of intracellular accumulation of dysmetabolic products. The histological and electron microscopical similarity of corpora amylacea, Lafora bodies and Bielschowsky bodies suggest that all these structures are an unspecific, nearly identical endproduct of various intracellular metabolic disturbances. The pathognomonic significance of these structures depends on their regional distribution: the common corpora amylacea occur predominantly in the astroglia, the Lafora bodies typical in the neurons and the Bielschowsky bodies are restricted to the neurons of the exterior pallidum.

[Paracrystallic, intraplasmatic inclusion bodies in human hepatocytes: a structural analytic study (author's transl)]. / Parakristalline, intracytoplasmatische Einschlusskörper in menschlichem Leberparenchym: Eine strukturanalytische Studie

Electron micrographs from intraplasmatic inclusion bodies of human hepatocytes are described; these paracrystallic aggregations consist of helically arranged filaments. All the observed periodic structures within these bodies can be indicated as originating from the same compound by the use of the Frauenhofer diffraction pattern. Concerning the genesis of these characteristically structured bodies two possibilities are discussed: 1. A special polymeric form of fibrinogen and fibrin built up in vivo. 2. Polymerization of a monomeric enzyme, for example, glutamate dehydrogenase, to paracrystallic bodies by fixation-dependent cross-linkages.

[Banded filamentous associates in the intra- and extracellular space in connection with collagen degradation (author's transl)]. / Uber Vorkommen und Bedeutung extra- und intracellulärer periodisch gebänderter filamentärer Assoziate.

Banded fibrous associates are described in the extracellular space of connective tissue from human endometrium, Ehlers-Danlos syndrome and of tendon rupture. In the cases of morbus Dupuytren these associates are also found as intracellular inclusions. The banded structures are interpreted as states of an enzymatically induced degradation of collagen in correlation with Type-III collagen.

[Structure and mechanical properties of dermatosparactic collagen (author's transl)]. / Struktur und mechanische Eigenschaften dermatosparaktischen Kollagens.

Dermatosparactic calf-tail-tendon-collagen was investigated by mechanical measurements, electron microscopy and x-ray diffraction. We suppose, that the tensile strength decrease of the fibres is due to the irregular aggregation of subfibrils to fibrils. The x-ray diagram of the fibre is not influenced by state of disorder. Cyclic extension of dermatosparactic collagen leads to a higher increase in tensile strength than in the case of normal calf tendon. The effect might be due to the increase of fibril- and area-density resulting in an augmentation of crosslinks.

[Aetiology of dupuytren's contracture (author's transl)]. / Zur Atiologie der Kontraktur beim Morbus Dupuytren

Regarding experimental data on the multi-factorial reduction of the thermostability of collagen, the following sequence of the mechanism of Dupuytren's contracture is discussed: 1. Hereditary or acquired weakness of fibres of the palmar fascia 2. Further disturbance of the physical property of collagen by the cumulative effects of mechanical, i.e. traumatic, influence. 3. By this means an induced stepwise shrinkage of released fascial fibres in body temperature. 4. Stabilisation of the shortening (contracture) by development of collagen. This hypothesis is supported by histological, polarizing-microscopic, electron-microscopic and chemical results.

[Trace elements in several organs and mechanical properties of collagen under the influence of D-penicillamin (author's transl)]. / Der einfluss von D-Penicillamin auf den Gehalt einiger Organe an Spurenelementen sowie auf die mechanischen Eigenschaften von Kollagen.

The content of trace elements in several organs of rats under the influence of D-penicillamine (D-PA) was investigated by the neutronactivation-analysis. It could be shown an diminution of Cu, and Co under D-PA-treatment, the content of Fe, Mn, Rb and Zn was not influenced. The investigated organs didn't show any submicroscopic alterations under D-PA. On isolated collagen fibrils of tail tendon was seen a significantly diminuition of E-moduls. In accordance with Siegel the principal effect of D-PA is thought to block the synthesis of functional groups from Schiff-base crosslink precursors but not to inhibit lysyloxidase by loss of Cu-ions of connective tissue. The thermostability of D-PA influenced fibrils is changed in stretched state only and will be due to the lack of crosslink Schiff-bases; where as the shrinking point of not stretched fibrils shows only aging dependent changes.

[Kinking deformities in collagen (author's transl)]. / Knickdeformationen an Kollagen.

The affect of stretch on collagen was investigated. Alterations of mechanical dimensions and thermostability of fibrils were measured and changes in fine structure determined by x-ray diffraction and electronmicroscopy. Collagen underwent changes both in tensile strength and fine structure following stretch beyond the physiological range. The severity of these changes depended both on the degree of stretch and the cross-link density of the collagen Fibrils either became split into bundles consisting of subfibrillar units or showed circumscribed kinking deformities. The mechanism producing kinking was investigated. It is possible that a connection exists between fibrillar kinking and tendon rupture.

[On the determination of changes in the large periodic structure of collagen (author's transl)]. / Uber die Bestimmung von Langperioden-Anderungen am Kollagen.

Changes in the large periodic structure of collagen were investigated with the aid of synchrotron radiation. Following results were obtained: 1) Macroscopic extension results in elastic deformation of the elements which are determinant for the structure. 2) The increase of the large period is not proportional to the macroscopic stress. 3) The interpretation of these facts requires a mechanical coupling between the structural units. Up to extensions of 4% this coupling is produced by means of a viscoelastic matrix. 4) In all probability the polypeptide helices are deformed in an inhomogeneous mode. The results were set against measurements on human tendon and on artificially crosslinked collagen. The relations between the mechanical behaviour and the change of the large period were compared with the properties of a mathematical model.

Ehlers-Danlos syndrome type IV (EDS IV) as model of a defective biopolymer composite material.

The connective tissue of a lethal EDS IV case was investigated for the reasons of the manifested disturbances of the arterial wall. This functional disorder was attributed to the mechanical decoupling of elastin and collagen, with the premise of a composite material consisting of cellular, fibrillar, lamellar and other matrix components. A conceivable relation between the manifested deficiency of type III collagen and a disturbed anchoring of elastin is shown. These findings are supported by biochemical, morphological, x-ray and mechanical data.

[Disordered fibrillar structure in ruptured tendons (author's transl)]. / Fibrilläre Gefügestörung bei Sehnenruptur.

Areas of disordered fibrillar structure similar to kinking deformities have been observed in specimens from ruptured tendons. It seems possible to compare this phenomenon with experimentally produced deformations. The significance for the pathomechanics of tendon rupture is discussed.