Collagen ; biosynthesis ; Liver Cirrhosis ; metabolism ; pathology

OBJECTIVEThe aim of this review is to comprehensively and unbiasedly summarize the improvements in the techniques for classical corneal collagen cross-linking (CXL) by covering the reasons for this improvement, measure, and effect to approach the future direction of the CXL.

DATA SOURCESAll articles used in this review were mainly retrieved from the PubMed database.

STUDY SELECTIONOriginal articles and reviews were selected if they were related to the improvement in the technique of classical CXL. Data were mainly extracted from 94 articles, which are listed in the reference section of this review.

RESULTSThis innovative research involves every step such as instrument preparation, epithelial management, riboflavin instillation, and UVA irradiation. These clinical and experimental results seem promising.

CONCLUSIONSCXL treatment is the only recent promising method for preventing the progress of keratoconus. The limitations and potential complications that accompany classical CXL such as corneal thickness limitations, ultraviolet-A (UVA) light injury, and the impact of de-epithelialization encourage people to research new improvements in techniques. While this research needs to be further investigated, we hope our review can help related researchers and patients.

Collagen ; metabolism ; Cornea ; metabolism ; radiation effects ; Humans ; Ultraviolet Rays

Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects. In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing. A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control. Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C. In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous). Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.
Animal ; Cattle ; Collagen/ultrastructure ; Collagen/radiation effects* ; Collagen/metabolism ; Elasticity ; Membranes, Artificial* ; Microscopy, Electron, Scanning ; Porosity ; Tensile Strength ; Ultraviolet Rays*

BACKGROUND: Recent clinial observations have suggested that colchicine, which is in frequent use in gout can affect the conneciive tissue metabolism in skin and other ti.ues. OBJECTIVE: This study suggest that further development of colchiine might provide a novel means of modulating collagen gen expression in patients with fibrotic disease. METHOD: We examed the effect of colchicine on the expres, on of collagen, fibronectin and collagenase gene by skin filroblast culture hy Nort.hern and dot-blot iybridization. Result : The rate of transcription of genomic DNA corresponding o type I collagen and libvonectin was reduced in colchicine-treated cultures but collagenase was not. reduced. Canclusion : The microti.ikile disruptive agent, colchicine, reduced the expression of type I collagen and fibronectin in a dose-(lependent manner. This st.udy suppor that colchicine is one of the promising antifibrogenic drugs curvently being tested as a treatment, of hun an fibrotic disease.
Colchicine* ; Collagen Type I ; Collagen* ; Collagenases ; DNA ; Fibroblasts ; Fibronectins ; Gene Expression* ; Gout ; Humans ; Metabolism ; Skin

PURPOSE: This study was designed to measure time-dependent changes in muscle excursion and collagen content after tenotomy, and to analyze the correlation between muscle excursion and collagen content in a rabbit model. MATERIALS AND METHODS: Twenty-four rabbits underwent tenotomy of the second extensor digitorum longus (EDL) muscles on the right legs and were randomly assigned to three groups based on the period of time after tenotomy (2, 4, and 6 weeks). The second EDL muscles on left legs were used as controls. At each time after tenotomy, passive muscle excursion and collagen content, determined by hydroxyproline content, were measured bilaterally, and the ratio of each value to the normal one was used. RESULTS: The mean ratio of muscle excursion after tenotomy to the value of the control decreased in a time-dependent fashion: 92.5% at 2 weeks, 78.6% at 4 weeks, and 55.1% at 6 weeks. The mean ratio of hydroxyproline content in muscle to the value of the control increased in a time-dependent fashion: 119.5% at 2 weeks, 157.3% at 4 weeks, and 166.6% at 6 weeks. There was a significant negative correlation between the ratio of hydroxyproline content in muscle after tenotomy to the control values and the ratio of muscle excursion after tenotomy to the control values (r=-0.602, p=0.002). CONCLUSION: The decrease in muscle excursion seems to correlate with the increase in collagen content in the muscle in a time-dependent fashion following tenotomy.
Animals ; Collagen/*metabolism ; Hydroxyproline/metabolism ; Muscle, Skeletal/*metabolism ; Rabbits ; Tendon Injuries/*metabolism ; Tendons ; Tenotomy ; Time Factors

OBJECTIVETo evaluate the effect of dentin matrix metalloproteinase (MMP) on the degradation of root dentin collagen.

METHODSRoot dentin powder was demineralized with acetic acid (pH 4.0) at 4 degrees C for 14 d, then dialysed and centrifuged. Precipitation was divided into 7 groups, with 6 samples in each group, and each sample was 50.0 mg. One milliliter artificial saliva with a different reagent was added in each sample respectively. The reagents were 2 mmol/L APMA (MMP activator), 2 mmol/L EDTA, 100 mmol/L EDTA, 200 mmol/L EDTA, 0.2% and 0.02% chlorhexidine (MMP inhibitor), and the blank artificial saliva was taken as control. The amount of degraded collagen of each sample was determined with hydroxyproline assay kit. Scanning electron microscope was employed to observe the morphological and structural changes of root dentin which was demineralized or put into artificial saliva after being demineralized.

RESULTSThe mean amount of degraded collagen in APMA group was significantly higher than that in the blank group (P < 0.05). The mean amount of degraded collagen in 2 mmol/L, 100 mmol/L, 200 mmol/L EDTA, 0.02% and 0.2% chlorhexidine groups was dramatically lower than that of the APMA group and the blank (P < 0.01). SEM observation indicated that the structural integrity of the collagen network on root surface dentin still existed in root dentin surface after being demineralized alone, while collagenous fibril was destructed and the structural integrity on root dentin surface disappeared after being demineralized and treated by artificial saliva.

CONCLUSIONSMMP in root dentin can degrade root dentin collagen after being activated at low pH followed by neutralization. The results suggest that host MMP may play an important role in the process of dentin caries formation.

Collagen ; metabolism ; Dental Caries ; enzymology ; Dentin ; metabolism ; Humans ; In Vitro Techniques ; Matrix Metalloproteinases ; metabolism ; Tooth Root ; metabolism

It is very difficult to diagnosis osteoarthritis in the early stage, due to the slow development of the disease, no symptoms occures, and no X-ray findings in the early stage, it is difficult to early diagnosis with the traditional diagnostic methods, resulting in the poor treatment outcome, and even some patients develop joint deformity, activity limitation, and must take an operation, it brought great pain and heavy financial burden to patients. How to early diagnosis of articular cartilage injury become difficult now. Some scholars suggest that to those suspected patients, the arthroscopic diagnosis must be taken. Although the small trauma and quick recover, the method of operation has trauma, not only increase the suffering of the patients, but the treatment is very expensive, make the patients finch. A large number of domestic and foreign scholars to study patients with OA to find the ideal fluid biological markers (BM) to reflect articular cartilage metabolism, and revealed disease activity or prognosis. The CTX-II can reflect degradation of the articular cartilage.
Biomarkers ; metabolism ; Collagen Type I ; metabolism ; Humans ; Osteoarthritis ; diagnosis ; metabolism ; Peptides ; metabolism

The genes that codify the subunits of the fibril-forming collagen constitute an evolutionarily related group within the collagen multigene family, Deposition of fibrillar molecules in the extrcellular matrix of several tissues influences a number of cellular activities such as adhesion, proliferation, and migration. In the developing and adult organisms, temporal and spatial expression of collasgen genes is modulated by a variety of cytokines and hormones, Likewise, transcription of collagen genes in tissue cultures can be greatly affected by the action of these substances and by chemical or viral transformation as well. Cytokine-mediated increase of collagen deposition on response to environmental stimuli is also the major histopathological feature of clinically distinct that similarly lead to overt firrotic processes. It is my heartily with to elucidate the mechanisms that regulate tissue specific expression of the human collagen genes a prerequisite for understanding the pathophysiology of diseased processes. Involving collagen metabolism, such as scleroderma.
Adult ; Collagen* ; Cytokines ; Gene Expression* ; Humans ; Metabolism ; Multigene Family ; Psoriasis

A porcine heart valve was irradiated by Ultraviolet (UV) rays (10 W, 254 nm) for 2, 4, 8 and 24 hours at 4 degrees C to cross-link the structural collagen matrix. The degree of cross-linking was evaluated by assaying the released amount of hydroxyproline (Hyp) from the matrix, and comparing it with the positive controls of valves treated by glutaraldehyde (GA) solution (0.625 wt%) and the negative controls of non-treated fresh valves. The undigested weight ratio of the specimens increased by increasing the UV irradiation time. The undigested weight of the leaflets, tunica interna and tunica externa of the fresh, GA-treated and UV-irradiated specimens after collagenase digestion was compared. As UV irradiation increased, the amount of released hydroxyproline was gradually decreased until 8 hours of irradiation, after which the released hydroxyproline-reduction occurred slightly until 24 hours of irradiation time in this system. A total 47.68% of the hydroxyproline in the valve was cross-linked by UV irradiation after 24 hours, while 73.74% of the hydroxyproline in the positive control was crossed-linked. Light microscopic observation revealed that the typical crimp pattern of collagen fibers decreased and was rearranged into a dense flattened pattern as the UV irradiation induced interfibrilar cross-linking. GA-treated valves demonstrated a denser matrix pattern than the UV-irradiated specimens. Cross-linked collagenous tissue prepared by UV irradiation would be useful for improving durability and reducing the disadvantages related to using a chemical cross-linking agent.
Animal ; Aortic Valve/radiation effects* ; Aortic Valve/metabolism* ; Collagen/radiation effects* ; Collagen/chemistry* ; Hydroxyproline/metabolism ; Swine ; Ultraviolet Rays*

BACKGROUNDBone morphogenetic protein (BMP)-2, alkaline phosphatase (ALP), and collagen type I are known to play a critical role in the process of bone remodeling. However, the relationship between mechanical strain and the expression of BMP-2, ALP, and COL-I in osteoblasts was still unknown. The purpose of this study was to investigate the effects of different magnitudes of mechanical strain on osteoblast morphology and on the expression of BMP-2, ALP, and COL-I.

METHODSOsteoblast-like cells were flexed at four deformation rates (0, 6%, 12%, and 18% elongation). The expression of BMP-2 mRNA, ALP, and COL-I in osteoblast-like cells were determined by real-time quantitative reverse transcription polymerase chain reaction, respectively. The results were subjected to analysis of variance (ANOVA) using SPSS 13.0 statistical software.

RESULTSThe cells changed to fusiform and grew in the direction of the applied strain after the mechanical strain was loaded. Expression level of the BMP-2, ALP, and COL-I increased magnitude-dependently with mechanical loading in the experimental groups, and the 12% elongation group had the highest expression (P < 0.05).

CONCLUSIONMechanical strain can induce morphological change and a magnitude-dependent increase in the expression of BMP-2, ALP, and COL-I mRNA in osteoblast-like cells, which might influence bone remodeling in orthodontic treatment.

Alkaline Phosphatase ; metabolism ; Analysis of Variance ; Animals ; Bone Morphogenetic Protein 2 ; metabolism ; Cell Line ; Collagen ; metabolism ; Collagen Type I ; metabolism ; Mice ; Osteoblasts ; cytology ; metabolism