Ossified lipoma of the interpeduncular fossa: a case report and review of the literature

We report two cases of Creutzfeld-Jakob disease with clusters of giant collagen fibers. To our knowledge, these abnormally large collagen fibers have never been described in patients with degenerative diseases of the central nervous system. The significance of the formation of such plaque-like large collagen fibers has as yet not been elucidated. It is felt that these represent a product of the degenerative process.     

Interpreting the equatorial diffraction pattern of collagenous tissues in the light of molecular motion

The equatorial diffraction pattern associated with collagenous tissues, particularly type I collagen, is diffuse and clearly unlike that from crystals. Hukins and Woodhead-Galloway proposed a statistical model that they termed a "liquid crystal" for collagen fibers in tendons. Fratzl et al. applied this model to both unmineralized and mineralized turkey leg tendon, a model that ignores the organization imposed by the well-known cross-linking. The justification for adopting this model is that the curve fits the data. It is shown that the data can be equally well matched by fitting a least-squares curve consisting of a second-order polynomial plus a Gaussian. The peak of the Gaussian is taken as the equatorial spacing of the collagen. A physical explanation for this model is given, as is a reason for the changes in the spacing with changes in water content of the tissue. The diffusion is attributed to thermally driven agitation of the molecules, in accordance with the Debye-Waller theory including the Gaussian distribution. The remainder of the diffusion is attributed to other scattering sources like the mineral crystallites.     

Sugars and polyols inhibit fibrillogenesis of type I collagen by disrupting hydrogen-bonded water bridges between the helices

To better understand the mechanism of collagen fibrillogenesis, we studied how various sugars and polyols affect the formation and stability of collagen fibers. We combined traditional fiber assembly assays with direct measurement of the interaction between collagen triple helices in fibers by osmotic stress and X-ray diffraction. We found that the effects of sugars and polyols were highly specific with respect to small structural differences between these solutes. For example, 1,2-propane diol only weakly inhibited the fiber assembly and practically did not affect the interaction between collagen helices in fibers. At the same concentration, 1,3-propane diol eliminated the attraction between collagen helices and strongly suppressed fibrillogenesis. The two diols have the same atomic composition and differ only by the position of one of their hydroxyls. Still, their ability to inhibit fiber assembly differs by more than an order of magnitude, as judged by protein solubility. We argue that this is because collagen fibrillogenesis requires formation of hydrogen-bonded water clusters bridging recognition sites on the opposing helices. The ability of various sugars and polyols to inhibit the fiber assembly and to destabilize existing fibers is determined by how efficiently these solutes can compete with water for crucial hydrogen bonds and, thus, disrupt the water bridges. The effect of a sugar or a polyol appears to be strongly dependent on the specific stereochemistry of the solute hydroxyls that defines the preferred hydrogen-bonding pattern of the solute.     

Scattering of light from histologic sections: a new method for the analysis of connective tissue

We have developed a light scattering technique that can be used to analyze the orientation and diameter of collagen fibers in histologic sections of connective tissue. Scattering patterns obtained by transmitting laser light through sections of tissue contain information both on the orientation, degree of alignment, and size of the constituent collagen fibers. Analysis of the azimuthal intensity distribution of scattered light yields numerical values of the degree of alignment by use of an orientation index, S, which is chosen to vary between 0 for randomly oriented fibers and 1 for a perfectly aligned arrangement. The average diameter of the collagen fibers is calculated from the scattering angle at which the intensity reaches its first minimum. These measurements are independent of the nature of histologic stain. The procedure is illustrated by measurements obtained with sections of the guinea pig dermis and of control scar. We conclude from our experiments that light scattering can complement the analysis of tissue architecture typically performed with the light microscope.     

Computerized morphometric quantitation of elastin and collagen in SMAS and facial skin and the possible role of fat cells in SMAS viscoelastic properties

Recently, the superficial musculoaponeurotic system (SMAS) was found to be a composite tissue comprising collagen, elastic fibers, and fat cells in an extracellular viscous matrix. Both SMAS and facial skin tissues exhibit viscoelastic properties, but SMAS tissue has delayed stress relaxation. As a consequence, SMAS is viewed as a firmer elastic foundation for the more viscous facial skin. In some patients, a slackening effect of SMAS tissue takes place over a period ranging from weeks to months after tightening. To determine the relative quantity of viscoelastic components and better understand their biomechanical behavior, a quantitative morphometric study of the elastic and collagen fibers in the SMAS and facial skin was conducted. Thirty-four SMAS preparations were taken from 17 patients during either primary face lift operations (12 women) or reoperative face lift procedures (4 women, 1 man), which were performed 4 to 9 months after the original surgery, to examine the elastin and collagen content. For comparison, preauricular skin was also gathered from these patients. The specimens were stained with Weigert's staining to identify elastin and collagen fibers. Using a computerized morphometric analysis, 100 fields of each SMAS and skin specimen were examined. According to our findings, the average percentage of elastin and collagen fibers in SMAS and facial skin was as follows: (1) the percentage of elastin fibers in the SMAS was 4.71 +/- 1.2 (standard error of mean +/- 0.0291); (2) the percentage of elastin fibers in the skin was 6.1 +/- 1.8 (standard error of mean +/- 0.0436); (3) The percentage of collagen fibers in the SMAS was 38.7 +/- 5.9 (standard error of mean +/- 0.1430); and (4) the percentage of collagen fibers in the skin was 48.47 +/- 6.96 (standard error of mean +/- 0.1688). A statistical significance of p < 0.0001 was demonstrated between the collagen and elastin groups. A different percentage of elastin and collagen fibers was found among the 17 patients and within each of them separately. Neither gender nor age differences were found regarding elastin and collagen fiber content. No statistical differences were demonstrated between specimen sources, i.e., whether the operations were primary or reoperative face lift procedures. Findings from previous studies indicate that the cheek has two viscoelastic layers, the skin and the SMAS. The proportional similarity in average percentages of elastin and collagen in SMAS and facial skin cannot explain the relatively delayed stress relaxation effect of the SMAS. Therefore, the fat cells that are found exclusively in the SMAS probably lend a certain degree of firmness to this layer and play a significant role in the long-term efficacy of SMAS surgery.     

Ultrastructure of collagen fibers in the outer membrane of recurrent chronic subdural hematoma

The three-dimensional structure of the collagen fibers in the outer membrane of recurrent chronic subdural hematoma was studied by scanning electron microscopy (SEM). Specimens obtained at surgery were treated with NaOH at room temperature to digest away all cellular components and expose the collagen fibers. SEM observation of the dural side of the outer membrane showed the collagen fibers were woven into a compact feltwork with a dense arrangement. The fiber bundles had a honeycomb structure framed by the collagen fibers. Observation of the hematoma side found the collagen bundles had a sparse wavy appearance. The arrangement of the collagen fibers on the dural side is different from that on the hematoma side. The thick outer membrane may be formed by granulation resulting from inflammatory reaction. Collagen fibrillar networks are not fragile, and may reinforce the outer membrane of the recurrent hematoma.     

Morphologic changes in collagen fibers after 830 nm diode laser welding

BACKGROUND AND OBJECTIVE: The mechanism of laser tissue welding is elusive, but collagen transitions are somehow involved. Collagen fiber modifications observed after 830 nm diode laser welding are presented in this study. STUDY DESIGN/MATERIALS AND METHODS: A 830 nm diode laser assisted longitudinal aortorrhaphy was performed on 37 Wistar rats, with shots of 0.5 W in power, 8 sec in duration and 250 W/cm2 in irradiance. Energy utilized ranged from 400-550 J/ mm2 for 1 cm-length of anastomosis. After laser welding, histological modifications in collagen fibers were observed through optic, scanning electron, and electron microscopic examination. RESULTS: After laser welding, collagen fibers lost a proportion of birefringence. Under electron microscope, the different changes in collagen fibers were visualized being either fused, "roped," swollen, or dissolved, surrounded by normal ones situated in the same zone. CONCLUSION: These data suggest that diode laser heating denatured part of the collagenic fibers, and that these morphologic changes play an important role in laser welding.     

Morphometric studies of collagen and fibrin lattices contracted by human gingival fibroblasts; comparison with dermal fibroblasts

Cell shape variations and substratum re-organization during contraction of floating collagen and fibrin lattices seeded with human gingival fibroblasts were determined by computerized image analysis of light and scanning electron microscopic images. Data were compared with those obtained with lattices populated with human dermal fibroblasts. The extent of collagen lattice contraction was similar with both cell types, resulting in a two-fold decrease in the area fractions occupied by collagen fibers. Fibroblasts exhibited a rounded shape (form factors equal to 0.8 and 0.7 for gingival and dermal cells, respectively) at day 1 of culture; they possessed a more elongated appearance (with form factors equal to 0.3 and 0.15 for gingival and dermal cells, respectively) at day 7. Continuous (gingival) and discontinuous (dermal) layers of cells were evidenced at the cortex of lattices. Contractions were associated with a significant reduction of the diameters of collagen fibers. Re-organization of substratum, as analyzed by the "Rose of Directions" technique, was evidenced only at the vicinity of filopodia where fibers ran parallel to these protrusions. Several lysed matrix cavities were observed when fibrin lattices were populated with gingival but not dermal fibroblasts at day 5 of culture. Although cells in fibrin lattices exhibited morphometric parameters comparable with those in collagen lattices, no fibroblast layers could be demonstrated at gel peripheries. Fibrin matrices consisted of an isotropic network of entangled fibrin filaments from the start of culture, and only a slight reduction of the diameters of fibrin fibers could be evidenced in dermal fibroblast-populated lattices. Fibrinolysis at the vicinity of gingival fibroblasts led to an entire re-organization of substratum toward the formation of larger fibers. The differential behavior of gingival vs. dermal fibroblasts inside fibrin but not collagen matrices could therefore partly explain the increased rate of remodeling of gingiva as compared with dermis.     

Actin cleavage in various tumor cells is not a critical requirement for executing apoptosis

The function of the urinary bladder is to store urine at low pressure and expel it periodically. To accomplish this, it must have the appropriate structural properties to accommodate slow but continuous volume changes. While much is presently known about the functional measurements of compliance, relatively little is known about the structural basis of compliance. In the present study, immunohistochemistry has been used to localize type III collagen fibers in the bladder wall at different intravesical volumes. To improve the resolution of these fibers, confocal microscopy was utilized to determine the changes in type III collagen fiber orientation and correlate them with the degree of mechanical distension of the bladder wall at partial and full capacity. We demonstrate that there were significant changes in both the orientation and conformation of type III collagen fibers during bladder filling. These observations support the view that volume accommodation in the bladder is achieved by changes in the arrangement of type III collagen. These data suggest that abnormal deposition or arrangement of type III collagen fibers can have an impact on normal bladder function.     

The anatomy of the tunica albuginea in the normal penis and Peyronie's disease

PURPOSE: We studied the fine architecture of the tunica albuginea of the penis. MATERIALS AND METHODS: The study included 6 human male cadavers and 10 surgical patients (5 with Peyronie's disease and 5 with normal penile anatomy). RESULTS: The tunica albuginea of the corpora cavernosa is a bi-layered structure with multiple sub layers. Inner layer bundles support and contain the cavernous tissue and are oriented circularly. Radiating from this layer are intracavernous pillars acting as struts, which augment the septum and provide essential support to the erectile tissue. Outer layer bundles are oriented longitudinally. These fibers extend from the glans penis to the proximal crura, where they insert into the inferior pubic ramus. There are no outer layer fibers between the 5 and 7 o'clock positions. Elastic fibers normally form an irregularly latticed network on which collagen fibers rest. In Peyronie's disease the well ordered appearance of the collagen layers is lost: excessive deposits of collagen, disordered elastic fibers and fibrin are found within the region of the plaque. CONCLUSIONS: The normal 3-dimensional structure of the tunica affords great flexibility, rigidity and tissue strength to the penis, which are lost consequent to structural changes in Peyronie's disease.     

Procollagen propeptide and pyridinium cross-links as markers of type I collagen turnover: sex- and age-related changes in healthy children

The correlations among age, gender, body size parameters, and type I collagen metabolism were evaluated in 183 healthy infants, aged 8.5-27.5 months. Collagen formation was assessed by measuring serum type I collagen carboxy-terminal propeptide, and degradation was determined by urinary pyridinoline and deoxypyridinoline (measured by high performance liquid chromatography) and cross-linked N- and C-terminal telopeptides of type I collagen (measured by NTx and CrossLaps assays). A new RIA specific for deoxypyridinoline was also evaluated. The results provide reference values at 10 months and 2 yr of age, including cross-linked C-terminal telopeptides (1492 +/- 685 and 1510 +/- 446 in boys; 1705 +/- 612 and 1849 +/- 611 micrograms/mmol creatinine in girls; mean +/- 1 SD). There was a good correlation between the high performance liquid chromatography and RIA data for deoxypyridinoline, showing that the RIA method is suitable for use in healthy children. Some correlations were found among peptide-bound cross-links, serum type I collagen carboxy-terminal propeptide, and the anthropometric parameters, suggesting that these peptides reflect bone resorption and also overall body type I collagen. Finally, there were age- and sex-related differences in the urinary excretion of the collagen degradation markers, suggesting that, unlike boys, girls maintain a high degree of collagen degradation up to the age of 24 months despite a decrease in their rate of collagen formation.     

Ultrastructure of collagen thermally denatured by microsecond domain pulsed carbon dioxide laser

BACKGROUND: Clinical improvement in photodamaged skin after carbon dioxide (CO2) laser resurfacing is thought to result in part from thermal collagen shrinkage. The presence of such collagen has not been unequivocally demonstrated. To identify and characterize the morphological features of collagen after CO2 laser exposure, we irradiated ex vivo human facial skin and bovine calcaneus tendon with microsecond domain pulsed CO2 laser energy and examined specimens for histopathological and ultrastructural changes in collagen. OBSERVATIONS: In dermis and tendon, 3 zones of collagen structure were apparent on electron microscopy. The first, most superficial zone demonstrated loss of collagen structure. The second zone consisted of admixed normal collagen fibers and thickened collagen fibers. Zone 3 consisted of normal-appearing collagen fibers. CONCLUSIONS: Ultrastructural examination of irradiated collagen revealed distinct morphological zones of denatured collagen fibers. Partially denatured fibers had an increased diameter consistent with lineal shrinkage. Zonal distinction was undetectable by light microscopy. Ultrastructurally, the zones of denatured collagen located above the normal fibers correlated with the zone of altered material seen on light microscopy. These findings suggest that collagen fiber shrinkage does occur after pulsed CO2 laser irradiation and that this phenomenon contributed, at least in part, to the immediate tissue contraction observed clinically.     

Ultrastructural study on adhesions in internal derangement of the temporomandibular joint

PURPOSE: This study examined the ultrastructural characteristics of adhesions in the upper joint compartment of temporomandibular joint (TMJ). MATERIALS AND METHODS: Tissue biopsy specimens of adhesions were obtained during arthroscopic operation on 36 joints in 22 patients with internal derangement (ID). The biopsy specimens were examined by light and transmission electron microscopy. RESULTS: Adhesions were grossly divided into two types based on arthroscopic observation: 1) a band-like type, which connected the articular fossa and TMJ disc, and 2) a pseudowall-like type, which faced the synovial fluid and was lined by articular tissue. Two types of collagen arrangement were observed at the electron microscopic level: orderly arranged collagen bundles and randomly arranged collagen bundles. Orderly arranged collagen bundles were prominent in the band-like adhesions. In pseudowall-like adhesions, mainly the randomly arranged collagen bundles were seen. However, in some dense fiber parts, orderly arranged collagen bundles also were observed. In other pseudowall-like adhesions, only orderly arranged collagen bundles were seen. Elastic fibers were abundant in some pseudowall-like adhesions with randomly arranged collagen bundles. There were no elastic fibers in the band-like adhesions, some dense fiber parts of the pseudowall-like adhesion, pseudowall-like adhesions consisting of only orderly arranged collagen bundles, and in the synovial membrane. CONCLUSION: The different arrangement of collagen fibers and presence or absence of elastic fibers were observed in the two types of adhesions. These findings served to show that extracellular components correspond to a dysfunction involving an ID of TMJ.     

Amianthoid myofibroblastoma of the soft tissues

Myofibroblastoma (MF) is an uncommon, usually benign, mesenchymal tumor infrequently described in soft tissues. We report here on the clinicopathologic findings of a soft tissue MF (STMF) presenting in the neck of a 90-year-old man as a slowly growing and non-painful nodule, 4 cm in greatest diameter. Histology revealed a circumscribed lesion constituted of monomorphous bipolar spindle cells arranged in swirling fascicles with intervening broad bands of hyalinized collagen and well formed "amianthoid" fibers. Immunohistochemistry showed the spindle cells to be immunoreactive for vimentin, smooth muscle actin and muscle specific actin and, focally, for desmin; immunostaining for cytokeratin, epithelial membrane antigen, S-100 protein, factor VIII-related antigen, and CD34 was negative. Based on the present case and on those previously reported in the literature, STMF is characterized by: 1) exclusive incidence in the male sex; 2) variable immunoreactivity of the neoplastic cells for desmin, probably reflecting an origin from a peculiar subset of myofibroblasts, or, alternatively, a further myoid differentiation; 3) variable abundance of (hyalinized) collagen; 4) presence of amianthoid fibers. The combination of desmin immunoreactivity, frequently observed in MF of the breast, and amianthoid fibers, the main feature of MF of the lymph nodes, has never been observed in soft tissue MF. It is important to recognize STMF as a specific clinicopathologic entity to avoid confusion with other types of spindle cell proliferation and to differentiate it from other types of myofibromatosis.     

A scanning and transmission electron microscopic study of fiber arrangement in the hepatic capsule

The arrangement of fibrous elements in the rat hepatic capsule was examined under a scanning electron microscope (SEM) after alkaline or acid maceration of the serous coat, in conjunction with examination of the thin sections using a transmission electron microscope (TEM). The elastic fibers appeared as thin threads in a densely meshed network, lying just beneath the serous coat. Their surface was granular with short rods in the materials fixed with paraformaldehyde. In contrast, the collagen fibers were observed as relatively thick threads, with fascicles of collagen fibrils that were uniform in size. These fascicles extended in various directions to form rough meshes that were traversed by small fascicles and anastomosed with each other. The fibrous branches of the elastic fibers extended on or into the underlying collagen fibers to be anchored, while the collagen fibers converged on many areas of the liver surface, and were transferred into the interlobular connective tissues. The findings of the present study thus suggest that the fiber arrangement plays an effective role in the mechanical protection of the fragile liver cells and delicate serous cells from pressure and friction damage by the neighboring abdominal organs and walls of the abdominal cavity due to the elastic mobility of the subserosal elastic network in addition to the possible slippery cushion of a serous layer on the serous cells.     

Compressive and Tensile Properties of STS304-Continuous-Fiber-Reinforced Zr-Based Amorphous Alloy Matrix Composite Fabricated by Liquid Pressing Process

An STS304-continuous-fiber-reinforced Zr-based amorphous alloy matrix composite with excellent fiber/matrix interfaces was fabricated without pores and misinfiltration by liquid pressing process. Approximately 60 vol pct of continuous fibers were homogeneously distributed in the matrix, in which considerable amounts of polygonal and dendritic crystalline phases were formed by the diffusion of metallic elements from the fibers. The ductility of the composite under compressive or tensile loading was drastically improved over that of the monolithic amorphous alloy. According to the compressive test results, a strength of 700 to 830 MPa was sustained until reaching a strain of 40 pct, because fibers interrupted the propagation of shear bands initiated in the matrix and took over a considerable amount of load. Under tensile loading, the deformation and fracture occurred by crack formation and opening at matrices, necking of fibers, fiber/matrix interfacial separation, and cup-and-cone–type fracture of fibers, thereby resulting in a high tensile elongation of 27 pct.     

Collagen VI deficiency induces early onset myopathy in the mouse: an animal model for Bethlem myopathy

To gain insight into the function of type VI collagen, the col6a1 gene was inactivated by targeted gene disruption in the mouse. The homozygous mutants lacked collagen VI in the tissues and showed histological features of myopathy such as fiber necrosis and phagocytosis and a pronounced variation in the fiber diameter. Muscles also showed signs of stimulated regeneration of fibers. Necrotic fibers were particularly frequent in the diaphragm at all ages examined. Similar, although milder, alterations were detected in heterozygous mutant mice, indicating haploinsufficiency of the col6a1 gene function. The data led us to conclude that collagen VI is necessary for maintenance of the integrity of muscle fibers and that the col6a1 -deficient mouse can be considered an animal model of Bethlem myopathy.     

The influence of time on human breast capsule histology: smooth and textured silicone-surfaced implants

Although the histology of capsular tissue is well described in the literature, most studies in humans do not correlate histologic findings with implant age (number of years an implant was in place before sampling). As such, questions regarding the long-term histology in humans remain. The microanatomy of 93 human periprosthetic capsular tissues surrounding 22 textured and 71 smooth silicone-surfaced prostheses was studied. The implants were divided into two groups according to the time between implantation and capsulectomy: between 0 and 5 years or more than 5 years. Hematoxylin and eosin and Masson trichrome-stained sections were analyzed by light microscopy, with and without polarization. Eighteen of the textured implants contained silicone gel and four contained saline. Sixty of the smooth implants contained silicone gel, eight contained saline, and in three, the filler type was not known. For the majority of patients, surgery was performed for augmentation mammaplasty, and the implants were removed because of capsular contracture. The following histologic features were assessed: synovial-like metaplasia, villous hyperplasia, density of the collagenous capsule, alignment of collagen fibers within the capsule, and the presence of foreign material and of a foreign body reaction. The following trends were observed. In smooth implants, increasing implant duration was associated with a decrease in the presence of synovial-like metaplasia (p = 0.003) and villous hyperplasia; there was no significant difference in the presence of a dense collagenous capsule, the orientation of collagen fibers, or the presence of a foreign body reaction. An increase was observed in the presence of foreign material (p = 0.01). In textured implants, increasing implant duration was associated with a decrease in the presence of synovial-like metaplasia, villous hyperplasia (p = 0.003), dense collagenous architecture, and parallel orientation of collagen fibers (p = 0.017). An increase in the presence of a foreign body type reaction and foreign material (p = 0.024) was observed. In comparing textured and smooth-surfaced implants, synovial-like metaplasia was observed more often in the textured group, both at 0 to 5 years (p = 0.01) and at greater than 5 years (p < 0.01). Textured implants more often had villous hyperplasia at 0 to 5 years (p = 0.03) but not beyond 5 years. Smooth implants more often had a dense collagenous capsule than textured implants after 5 years. No significant difference was seen in the orientation of collagen fibers in capsules around smooth and textured implants at 0 to 5 years. After 5 years, the incidence of capsules with collagen fibers arranged parallel to the implant surface was significantly greater in the smooth group than in the textured group (p = 0.01). The presence of a foreign body type reaction was seen more often in the textured group between 0 and 5 years (p = 0.01) and at greater than 5 years (p < 0.01), and the presence of foreign material was more often seen in the textured group between 0 and 5 years (p = 0.06) and at greater than 5 years (p < 0.01). In summary, the cytologic changes around implants seem to be dynamic in nature, and implantation duration and shell type play a significant role. Synovial-like metaplasia, villous hyperplasia, and foreign material were more often observed in the textured group within the 0 to 5 year interval. Beyond 5 years, synovial-like metaplasia, a foreign body type reaction, and foreign material were more often observed in the textured group. Differences in the density of collagenous capsules were not significant at any time point, and collagen fibers oriented parallel to the implant surface were more often observed in the smooth group after 5 years. The significance of these findings awaits further investigation.