Denaturation of Collagen Via Heating: An Irreversible Rate Process

Wright, Neil T.; Humphrey, J. D.

doi:10.1146/annurev.bioeng.4.101001.131546

Cited by 221 publications

(184 citation statements)

References 39 publications

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“…Below these alterations, the intact collagen matrix might be observed. f Outermost surface composed by a thin carbonized layer which has some voids that separated the underlying surface, composed by a fused organic matrix and denatured collagen fibrils collagenous tissue [42] that could be represented in the photomicrographs as void spaces, like micro-fissures, where collagen fibrils were absent. Although collagen degradation took place at the molecular level [43], collagen plays an important role in the architectural structure of dentin and is intimately related to formation and stability of the hybrid layer, which is only formed by the interlocking of intact collagen fibrils with resin monomers of the adhesive systems, promoting micromechanical retention [44].…”

Section: Discussionmentioning

confidence: 99%

Impact of Er:YAG laser pulse duration on ultra-structure of dentin collagen fibrils

et al. 2018

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Purpose To evaluate the ultra-morphology of the dentin after irradiation with Er:YAG laser using shorter pulse durations in different protocols by transmission electron microscopy (TEM). The Er:YAG laser is an effective alternative method for hard dental tissue treatment with great acceptability among patients. However, undesirable effects may occur in dental substrate if the correct parameters are not chosen during irradiation protocols, jeopardizing bonding that could result in premature failures. But, before doing bonding tests, it is fundamental the knowledge of the laser action into dentin. It is well known that shorter pulses have less thermal damage due to less heat loss during irradiation; hence, it is primordial to evaluate the performance of shorter pulses in irradiation protocols. Methods Eighteen dentin disks with 2 mm thick were assigned into six experimental groups according to the irradiation protocol: cavity preparation (200 mJ and 20 Hz) and pretreatment (80 mJ and 2 Hz) varying the pulse duration (50, 300, or 600 μs), in focused distance and under refrigeration. Qualitative and semi-quantitative analyses were performed. Results The pretreatment with 50 μs was the protocol that maintained intact both architecture of collagens fibrils and an organized extracellular matrix. Nevertheless, the other groups showed a melted and carbonized dentin surface followed by fused zone of collagen fibrils with loss of interfibrillar spaces. Conclusions It was concluded that the thickness of the altered layer is directly proportional to the enhance of pulse duration for cavity preparation protocols tested. Moreover, pretreatment with 50 μs is an adequate protocol for dentin, which did not alter its ultra-morphology.

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Section: Discussionmentioning

confidence: 99%

Impact of Er:YAG laser pulse duration on ultra-structure of dentin collagen fibrils

et al. 2018

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“…24 DHT partially denatures collagen by breaking the hydrogen bonding needed to maintain the collagen triple-helix structure. 24,25 However, although DHT appears to have little effect on scaffold structure, it is not known if it affects the binding and release of insulin-like growth factor-1 (IGF-1) from this type of scaffold, and therefore we compared scaffolds cross-linked via DHT and EDC/NHS (þDHT) with scaffolds cross-linked by EDC/NHS only (ÀDHT).…”

Section: Introductionmentioning

confidence: 99%

“…[25][26][27] IGF-1 increases the amount of proteoglycan and type II collagen synthesized by chondrocytes, and promotes chondrogenesis in bonemarrow-derived stem cells such as mesenchymal stem cells. 26,28 In addition, IGF-1 also protects the ECM from interleukin-1 and tumor necrosis factor a-mediated degradation during cartilage injury; hence, this growth factor was selected as the growth factor of choice for the present study.…”

Section: Introductionmentioning

confidence: 99%

Binding and Release Characteristics of Insulin-Like Growth Factor-1 from a Collagen–Glycosaminoglycan Scaffold

Mullen

Best

Brooks

et al. 2010

Tissue Engineering Part C: Methods

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Tissue engineering is a promising technique for cartilage repair, but to optimize novel scaffolds before clinical trials, it is necessary to determine their characteristics for binding and release of growth factors. Toward this goal, a novel, porous collagen-glycosaminoglycan scaffold was loaded with a range of concentrations of insulinlike growth factor-1 (IGF-1) to evaluate its potential as a controlled delivery device. The kinetics of IGF-1 adsorption and release from the scaffold was demonstrated using radiolabeled IGF-1. Adsorption was rapid, and was approximately proportional to the loading concentration. Ionic bonding contributed to this interaction. IGF-1 release was studied over 14 days to compare the release profiles from different loading groups. Two distinct phases occurred: first, a burst release of up to 44% was noted within the first 24 h; then, a slow, sustained release (13%-16%) was observed from day 1 to 14. When the burst release was subtracted, the relative percentage of remaining IGF-1 released was similar for all loading groups and broadly followed t ½ kinetics until approximately day 6. Scaffold cross-linking using dehydrothermal treatment did not affect IGF-1 adsorption or release. Bioactivity of released IGF-1 was confirmed by seeding scaffolds (preadsorbed with unlabeled IGF-1) with human osteoarthritic chondrocytes and demonstrating increased proteoglycan production in vitro.

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“…Briefly, circumferential strips cut from the belly region were mounted under isometric tension in a bath of distilled water. The denaturation temperature (T d) is indicated by a sharp increase in tension (4,62) as the bath temperature is increased from ϳ20 to 90°C. Following the heating segment, a 90°C isotherm was maintained for 3 h, during which the isometric tension is supported largely by the denatured collagen in the sample.…”

Section: Denaturation Temperature Testing and Hydrothermal Isometric mentioning

confidence: 99%

Pregnancy-induced remodeling of heart valves

Pierlot

Moeller

Lee

et al. 2015

American Journal of Physiology-Heart and Circulatory Physiology

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Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves. HEART VALVES ARE COMPLEX and dynamic biological structures. They play important roles toward efficient cardiac pumping, ensuring unidirectional blood flow while opening and closing 3 billion times in a lifetime. The extent and the mechanisms via which the valves may adapt to changing loading conditions in either physiology or pathology remain unclear. Many investigations of valve adaptation have focused on physiological development (8,20,(51)(52)(53) or pathological conditions such as left ventricular (LV) dysfunction (10), mitral valve regurgitation (58), myxomatous degeneration (19), or heart failure (17). Recent studies from our laboratory, however, have demonstrated the capacity of maternal heart valve leaflets to remodel under the altered hemodynamics of pregnancy, a nonpathological condition (38,39,60). Pregnancy is accompanied by an increase in blood volume and cardiac output of ϳ50%, as the maternal circulation accommodates the developing fetoplacental unit. This volume overload produces cardiac enlargement (21, 45, 60) with expansion of valve orifices (areas increasing from 12-53% in humans; see Refs. 9 and 43). These changes in geometry then elevate...

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Denaturation of Collagen Via Heating: An Irreversible Rate Process

Cited by 221 publications

References 39 publications

Impact of Er:YAG laser pulse duration on ultra-structure of dentin collagen fibrils

Impact of Er:YAG laser pulse duration on ultra-structure of dentin collagen fibrils

Binding and Release Characteristics of Insulin-Like Growth Factor-1 from a Collagen–Glycosaminoglycan Scaffold

Pregnancy-induced remodeling of heart valves

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