Control of the Collagen Fibril Diameter in the Equine Superficial Digital Flexor Tendon in Horses by Decorin

Watanabe, Takafumi; Hosaka, Yoshinao Z.; Yamamoto, Etsuji; Sugawara, Kenji; Takahashi, Hiroki; Takehana, Kazushige

doi:10.1292/jvms.67.855

Cited by 32 publications

(46 citation statements)

References 24 publications

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“…Semithin (1 lm) sections were cut, stained with toluidine blue, and observed by light microscopy to determine the orientation and obtain vertical sections. Ultrathin (80 nm) sections were cut using an ultramicrotome (MT-7000, RMC, USA) and stained, first with 0.2% tannic acid as a mordant for visualization of collagen (Afzelius, 1992;Watanabe et al 2005), and then with uranium acetate and lead citrate. The ultrathin sections were observed using a JEOL 100CX transmission electron microscope (Japan).…”

Section: Electron Microscopic Observationmentioning

confidence: 99%

The fibrous tapetum of the horse eye

et al. 2013

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The tapetum lucidum is a light-reflective tissue in the eyes of many animals. Many ungulates have a fibrous tapetum. The horse has one of the largest eyes of any living animal and also has excellent vision in low-light environments. This study aimed to clarify the macroscopic tapetal shape, relationship between the tapetal thickness and the degree of pigmentation of the retinal pigment epithelium (RPE), spatial relationship between the visual streak and the tapetum, and wavelength of the light reflected from the tapetum in the horse. Macroscopically, weak light revealed the tapetum as a horizontal band located dorsal to and away from the optic disc. The tapetum expanded dorsally as the illumination increased. The tapetal tissue consisted of lamellae of collagen fibrils running parallel to the retinal surface; these spread over almost the entire ocular fundus and were thicker in the horizontal band dorsal to the disc. Only the horizontal band of the tapetum was covered by unpigmented RPE, suggesting that this band reflects light and is responsible for mesopic and scotopic vision. The visual streak was located in the ventral part of the horizontal band, ventral to the thickest part of the tapetum. The wavelength of the light reflected from the horizontal band of the tapetum was estimated from the diameter and interfibrous distance of the collagen fibrils to be approximately 468 nm. Therefore, the light reflected from the tapetum should be more effectively absorbed by rods than by cones, and should not interfere with photopic vision.

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Section: Electron Microscopic Observationmentioning

confidence: 99%

The fibrous tapetum of the horse eye

et al. 2013

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“…The etiology of tendonitis has been discussed in many reports; however, there is little information regarding the mechanism of tendon degradation. Extracellular matrix (ECM) turnover in a tendon might occur repeatedly and routinely as in other connective tissues (13), and matrix metalloprotein-studies on three sites of the SDFT-the myotendinous junction (MTJ), mM and osteotendinous junction (OTJ)-revealed morphological and biochemical regional differences in vivo (33,39,40). We speculated that morphological structure corresponds to biomechanical function in some sites of the SDFT.…”

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Comparative study of the properties of tendinocytes derived from three different sites in the equine superficial digital flexor tendon

et al. 2010

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This aim of this study was to determine the characteristic differences in tendinocytes derived from three sites of the equine superficial digital flexor tendon (SDFT)-proximally the myotendinous junction (MTJ), mid-metacarpal (mM) and osteotendinous junction (OTJ)-in morphology, proliferation, and ability for synthesis of collagen and matrix metalloproteinases (MMPs). Little difference was observed in cell proliferation. Addition of tumor necrosis factor (TNF) α to the culture medium resulted in increased collagen synthesis by tendinocytes from all three sites. The amount of collagen synthesized by tendinocytes derived from the mM and OTJ was much larger than that synthesized by untreated tendinocytes. A collagen zymogram revealed that proMMP-13 synthesis was increased towards the distal site. However, TNFα treatment resulted in a significant decrease in the amount of proMMP-13 synthesized by tendinocytes from all three sites. On the other hand, a gelatin zymogram showed that the synthesis level of proMMP-9 tended to decrease towards the distal site, but there was little difference between synthesis levels of proMMP-9 before and after TNFα treatment. These results indicated that tendinocytes in the same tendon have different characteristics and that these characterisities would reflect the function of tendinocytes in vivo. Also, the isolated tendinocytes provided much information on the characteristics and properties of tendons for the ECM turnover system and on the responsiveness of tendinocytes to complex inflammatory responses in a tendinopathy condition.Tendon injury, especially in the superficial digital flexor tendon (SDFT), has proved to be a major problem for racehorses. Recent studies have shown that about 10-30% of racehorses suffer from tendonitis (8, 30). Interestingly, tendonitis occurs more frequently in the forelimb, especially in the SDFT rather than the deep digital flexor tendon (DDFT), and rarely occurs in the common digital extensor tendon (CDET) (1, 30). The vulnerability of the SDFT is related to its functions in weight supporting and in accumulation and transmission of elastic force for effective movement. Damage to the SDFT usually occurs during high-speed work or racing competition in which the forelimbs are pulled up to the highest position to bear maximum load or straining power (14,35). Moreover, tendonitis in the SDFT occurs in the mid-metacarpal (mM) site in most cases (1). Therefore, structural properties of the tendons might reflect the occurrence ratio of tendonitis (10). The etiology of tendonitis has been discussed in many reports; however, there is little information regarding the mechanism of tendon degradation. Extracellular matrix (ECM) turnover in a tendon might occur repeatedly and routinely as in other connective tissues (13), and matrix metalloprotein-

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“…Proteoglycans are classified into chondroitin sulphate (CS), dermatan sulphate (DS), heparan sulphate (HS), heparin or keratan sulphate according to their uronic acid subunit [3]. Decorin is the most abundant DS proteoglycan in tendon, and is reportedly involved in both the formation of collagen fibrils and adjustment of collagen fibril diameter [37]. However, its role in the turnover of tendon ECM has not yet been elucidated [16].…”

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Effect of Collagen Oligopeptide Injection on Rabbit Tenositis

Meguri

Minaguchi

Watanabe

et al. 2008

The Journal of Veterinary Medical Science

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ABSTRACT. Effects of the collagen oligopeptide (COP) were examined by its repeat injection into the inflammatory rabbit Achilles tendon (Tendo calcaneus communis), in which tenositis was induced by injection of bacterial collagenase. COP was evaluated 5 times over a period of 3 weeks to 1 month after injection of collagenase. At 1 month after treatment, the therapeutic effect of COP was evaluated by examining the structure of collagen fibrils, amount and components of glycosaminoglycans (GAGs) and matrix metalloproteinases (MMPs), and compared with the saline injection, control, and normal groups. The Achilles tendon of rabbit in the control group (no COP injection) and saline injection group showed a notable increase in the number of fine collagen fibrils, a change in GAG composition and increase in the amount of pro-MMP-2, indicating the weakening of the tendon. In contrast, the size distribution of collagen fibrils, GAG composition and the amount of pro-MMP-2 was similar to those in the normal group. These results suggest that COP injection promotes healing processes of the tendon injury. KEY WORDS: collagen fibril, collagen oligopeptide, electron microscopy, glycosaminoglycans, rabbit tendon.J. Vet. Med. Sci. 70(12): 1295-1300, 2008 The basic function of a tendon is to convey the force exerted by a muscle to the bone. The mechanical load is not transmitted directly to the bone because tendon is a highly flexible connective tissue. This connective tissue is composed of two components: tendon cells and extracellular matrix (ECM) that consists of collagen and proteoglycans [1,21]. Collagen in a tendon is composed of mainly type I collagen and is arranged into bundles of collagen fibrils that are further organized into tendon fascicles [22]. Proteoglycan has its core protein covalently bound to glycosaminoglycan (GAG). GAG is a non-branched polysaccharide consisting of repeated units of amino acids and uronic acids. GAGs in ECM exist as proteoglycans except for hyaluronic acid (HA) that exists as a free GAG. Proteoglycans are classified into chondroitin sulphate (CS), dermatan sulphate (DS), heparan sulphate (HS), heparin or keratan sulphate according to their uronic acid subunit [3]. Decorin is the most abundant DS proteoglycan in tendon, and is reportedly involved in both the formation of collagen fibrils and adjustment of collagen fibril diameter [37]. However, its role in the turnover of tendon ECM has not yet been elucidated [16].Matrix metalloproteinase (MMP) is an enzyme that has zinc ion in its active core and requires calcium ion for maintenance of the activity. More than 20 types of MMP have been reported so far, and they play an important role in the turnover of tendon ECM [7,34]. MMPs are divided into the following types: collagenase (MMP-1, -8, -13), gelatinase (MMP-2, -9), stromelysin (MMP-3, -10), membrane , and others (including MMP-7, -11, -12) according to their biochemical properties [4]. However, how these MMPs are involved in the turnover of tendon ECM remains unclear.Inflammation of a tendo...

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Control of the Collagen Fibril Diameter in the Equine Superficial Digital Flexor Tendon in Horses by Decorin

Cited by 32 publications

References 24 publications

The fibrous tapetum of the horse eye

The fibrous tapetum of the horse eye

Comparative study of the properties of tendinocytes derived from three different sites in the equine superficial digital flexor tendon

Effect of Collagen Oligopeptide Injection on Rabbit Tenositis

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