Genipin Protects Engineered Cartilage Against IL-1alpha Induced Degradation

2008 ◽  
Author(s):  
Andrea R. Tan ◽  
Eric G. Lima ◽  
Kacey G. Marra ◽  
Clark T. Hung
Keyword(s):  
Surgical Intervention ◽  
Crosslinking Agent ◽  
Blue Pigment ◽  
Naturally Occurring ◽  
Engineered Tissue ◽  
Interleukin 1Α ◽  
Amine Groups ◽  
High Concentrations ◽  
Engineered Cartilage ◽  
Dark Blue

Tissue-engineering has great potential for treating cartilage pathologies such as osteoarthritis by replacing degraded tissue with newly developed engineered tissue. However proinflammatory cytokines such as interleukin-1α (IL-1α) are a confounding issue as they are often present in high concentrations as part of the chronic pathology or as a result of the surgical intervention itself(1). The catabolic effects of these mediators may be especially pronounced in engineered tissues whose cells are not yet fully embedded in the potentially chondroprotective enclosure of a cartilaginous extracellular matrix(2). One method to protecting initially fragile constructs from degradation may be through the use of non-toxic cross-linking agents. Genipin is a naturally occurring crosslinking agent that reacts with amino acids or amine groups and leads to the formation of stable crosslinked products that are identifiable by a dark blue pigment (Figure 1). Cartilage cross-linked with genipin has been shown to be more resistant to collagenase digestion(3) and to injection of chondroitinase-ABC(4). In this study, we examined whether engineered constructs pre-treated with genipin would better resist IL-1α induced catabolic degradation.

Mesoscopic gelation of chitosan and genipin at below critical concentrations

2017 ◽  
Author(s):  
Christoph Engwer ◽  
Ronja Loy ◽  
Ioannis S. Chronakis ◽  
Ana C. Mendes ◽  
Francisco M. Goycoolea
Keyword(s):  
Sol Gel ◽  
Crosslinking Agent ◽  
Small Deformation ◽  
Macroscopic Appearance ◽  
Critical Concentrations ◽  
Gelation Kinetics ◽  
Gardenia Jasminoides ◽  
Sol Gel Transition ◽  
Low Cytotoxicity ◽  
High Concentrations

Genipin is increasingly used as a crosslinking agent for chitosans due to its low cytotoxicity as a naturally occurring extract of the plant <i>Gardenia jasminoides</i>. Genipin reacts with the primary amino groups of chitosan to form blue hydrogels. We studied the gelation kinetics of different chitosans varying in their properties (molar mass 34 000-213 000 g mol<sup>-1</sup>, degree of acetylation 9-20%) and genipin in detail. We found that critical sol-gel transition times obtained from dynamic light scattering were in good agreement with the results obtained by small deformation oscillatory rheometry and microviscosimetry at high concentrations of chitosan. However, at below critical concentrations, we found a second regime of gelation that followed the same Ross-Murphy's gelation kinetics. The macroscopic appearance of these samples was a suspension of weak gel-like particles that were sensitive to mechanical forces. We believe that the material is a mesoscopic gel, as described for other polymers. To the best of our knowledge, this is the first time that this phenomenon has been described for the gelling system of chitosan and genipin.

scholarly journals Desensitization Contributes to the Synaptic Response of Gain-of-Function Mutants of the Muscle Nicotinic Receptor

2006 ◽  
Vol 128 (5) ◽  
pp. 615-627 ◽  
Author(s):  
Sergio Elenes ◽  
Ying Ni ◽  
Gisela D. Cymes ◽  
Claudio Grosman
Keyword(s):  
Nicotinic Receptor ◽  
Dissociation Rate ◽  
Gain Of Function ◽  
Naturally Occurring ◽  
Channel Opening ◽  
Speed Up ◽  
High Concentrations ◽  
Dissociation Rate Constants ◽  
Kinetics Of ◽  
Peak Value

Although the muscle nicotinic receptor (AChR) desensitizes almost completely in the steady presence of high concentrations of acetylcholine (ACh), it is well established that AChRs do not accumulate in desensitized states under normal physiological conditions of neurotransmitter release and clearance. Quantitative considerations in the framework of plausible kinetic schemes, however, lead us to predict that mutations that speed up channel opening, slow down channel closure, and/or slow down the dissociation of neurotransmitter (i.e., gain-of-function mutations) increase the extent to which AChRs desensitize upon ACh removal. In this paper, we confirm this prediction by applying high-frequency trains of brief (∼1 ms) ACh pulses to outside-out membrane patches expressing either lab-engineered or naturally occurring (disease-causing) gain-of-function mutants. Entry into desensitization was evident in our experiments as a frequency-dependent depression in the peak value of succesive macroscopic current responses, in a manner that is remarkably consistent with the theoretical expectation. We conclude that the comparatively small depression of the macroscopic currents observed upon repetitive stimulation of the wild-type AChR is due, not to desensitization being exceedingly slow but, rather, to the particular balance between gating, entry into desensitization, and ACh dissociation rate constants. Disruption of this fine balance by, for example, mutations can lead to enhanced desensitization even if the kinetics of entry into, and recovery from, desensitization themselves are not affected. It follows that accounting for the (usually overlooked) desensitization phenomenon is essential for the correct interpretation of mutagenesis-driven structure–function relationships and for the understanding of pathological synaptic transmission at the vertebrate neuromuscular junction.

scholarly journals An Instrumented Bioreactor for Mechanical Stimulation and Real-Time, Nondestructive Evaluation of Engineered Cartilage Tissue

2012 ◽  
Vol 6 (2) ◽  
Author(s):  
Jenni R. Popp ◽  
Justine J. Roberts ◽  
Doug V. Gallagher ◽  
Kristi S. Anseth ◽  
Stephanie J. Bryant ◽  
...  
Keyword(s):  
Nondestructive Evaluation ◽  
Mechanical Stimulation ◽  
Ultrasonic Transducer ◽  
Testing Machine ◽  
Cartilage Tissue ◽  
Matrix Deposition ◽  
Intermittent Compression ◽  
Engineered Tissue ◽  
Engineered Cartilage

Mechanical stimulation is essential for chondrocyte metabolism and cartilage matrix deposition. Traditional methods for evaluating developing tissue in vitro are destructive, time consuming, and expensive. Nondestructive evaluation of engineered tissue is promising for the development of replacement tissues. Here we present a novel instrumented bioreactor for dynamic mechanical stimulation and nondestructive evaluation of tissue mechanical properties and extracellular matrix (ECM) content. The bioreactor is instrumented with a video microscope and load cells in each well to measure tissue stiffness and an ultrasonic transducer for evaluating ECM content. Chondrocyte-laden hydrogel constructs were placed in the bioreactor and subjected to dynamic intermittent compression at 1 Hz and 10% strain for 1 h, twice per day for 7 days. Compressive modulus of the constructs, measured online in the bioreactor and offline on a mechanical testing machine, did not significantly change over time. Deposition of sulfated glycosaminoglycan (sGAG) increased significantly after 7 days, independent of loading. Furthermore, the relative reflection amplitude of the loaded constructs decreased significantly after 7 days, consistent with an increase in sGAG content. This preliminary work with our novel bioreactor demonstrates its capabilities for dynamic culture and nondestructive evaluation.

NUTRITION OF A COBALAMIN-REQUIRING SOIL BACTERIUM

1957 ◽  
Vol 3 (2) ◽  
pp. 329-334 ◽  
Author(s):  
Milton K. Goldberg ◽  
S. H. Hutner ◽  
J. E. Ford
Keyword(s):  
Growth Response ◽  
Soil Bacterium ◽  
Intrinsic Activity ◽  
Vitamin B ◽  
Factor B ◽  
Naturally Occurring ◽  
High Concentrations

The pattern of the vitamin B12 requirement of a soil bacterium "Lochhead 38" (provisionally assigned to Arthrobacter) resembled that of the protozoan Ochromonas malhamensis and of higher animals. Of the naturally-occurring B12-vitamins, cyanocobalamin and vitamin B12III are active. Pseudovitamin B12 and Factor A have very little or no intrinsic activity, and when present in relatively high concentrations both compounds depress the rate of the growth response to limiting cyanocobalamin. Factor B, the porphyrin-like nucleus of the vitamin B12 molecule without the nucleotide, is inactive, as are also methionine and deoxyribosides. A disadvantage in the use of Lochhead 38 for assay purposes is that in vitamin-B12-dehcient cultures the organisms flocculate.

Partial purification of galactinol synthase from leaves of Cucurbita pepo

1982 ◽  
Vol 60 (7) ◽  
pp. 1054-1059 ◽  
Author(s):  
John A. Webb
Keyword(s):  
Cucurbita Pepo ◽  
Partial Purification ◽  
Galactinol Synthase ◽  
Inositol 1 ◽  
Mature Leaves ◽  
Galactosyl Transferase ◽  
Naturally Occurring ◽  
High Concentrations ◽  
Uridine Nucleotides

An enzyme synthesizing galactinol, UDP-D-galactose:myo-inositol-1-α-D-galactosyl transferase (galactinol synthase), has been isolated and partially purified from mature leaves of Cucurbita pepo. The enzyme showed optimal activity between pH 7.5 and 8.0 and required Mn2+ and the presence throughout isolation, storage, and assay of a sulfhydryl protectant (β-mercaptoethanol). EDTA was completely inhibitory. From a range of metal ions only Mg2+ partially replaced Mn2+, while Co2+, Zn2+, Cu2+, and Ni2+ were inhibitory. The uridine nucleotides and UDP-glucose were from 40 to 80% inhibitory and probably constitute part of the in vivo control system. High concentrations of galactose, melibiose, and xylose were partially inhibitory. The enzyme appeared highly specific for myo-inositol and showed no ability for galactosyl transfer to any other naturally occurring sugar or sugar alcohol. Some reactivity was obtained with the isomeric scyllo-inositol but the product was not identified. A range of other sugar nucleotides were unreactive.

scholarly journals Pro-Degradant Activity of Naturally Occurring Compounds on Polyethylene in Accelerate Weathering Conditions

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 195 ◽  
Author(s):  
Nadka Tzankova Dintcheva ◽  
Delia Gennaro ◽  
Rosalia Teresi ◽  
Marilena Baiamonte
Keyword(s):  
Thin Films ◽  
Thermal Analysis ◽  
Vitamin E ◽  
Light Exposure ◽  
Low Density Polyethylene ◽  
Accelerated Weathering ◽  
Low Density ◽  
Naturally Occurring ◽  
Accelerate Weathering ◽  
High Concentrations

In this work, naturally occurring compounds, such as Vitamin E (VE) and Ferulic Acid (FA), at high concentrations, have been considered as pro-degradant agents for Low Density Polyethylene (PE). However, all obtained results using the naturally occurring molecules as pro-oxidant agents for PE have been compared with the results achieved using a classical pro-oxidant agent, such as calcium stearate (Ca stearate) and with neat PE. The preliminary characterization, through rheological, mechanical and thermal analysis, of the PE-based systems highlights that the used naturally occurring molecules are able to exert a slight plasticizing action on PE and subsequently the PE rigidity and crystallinity slightly decrease, while the ductility increases. To assess the pro-degradant activity of the considered naturally occurring compounds, thin films of neat PE and PE-based systems containing 2 and 3 wt.% Ca stearate, VE and FA have been produced and subjected to accelerated weathering upon UVB light exposure. All obtained results point out that the VE and FA, at these high concentrations, exert a clear pro-oxidant activity in PE and this pro-oxidant activity is very similar to that exerted by Ca stearate. Moreover, the VE and FA at high concentrations can be considered as suitable eco-friendly pro-degradant additives for PE, also in order to control the polyolefin degradation times.

Phytoestrogens

1998 ◽  
Vol 4 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Rachel Mackey ◽  
John Eden
Keyword(s):  
Epidemiological Data ◽  
Asian Populations ◽  
Colon Cancers ◽  
Naturally Occurring ◽  
Urinary Levels ◽  
High Dietary Intake ◽  
High Concentrations ◽  
Relative Potencies

Phytoestrogens are defined as naturally occurring compounds found in plants that are structurally and functionally similar to 17-ß oestradiol or that produce oestrogenic effects. They are diphenolic in structure and are most commonly found in cereals, legumes and grasses. There have been numerous classes identified, the mostly highly investigated being isoflavones and lignans. Isoflavones are attenuated oestrogens. They behave both in vivo and in vitro as agonists and antagonists. Genistein and daidzein are found in high concentrations in soy beans and soy products. Their relative potencies as compared to oestradiol are low but they exhibit equivalent levels of bioactivity when tested in high concentrations. Lignans are found in oilseeds, cereals and berries. The main urinary lignans are enterolactone and enterodiol. Most phytoestrogens are modified by gut flora from glycoside precursors to a compound with oestrogenic properties. A high dietary intake of phytoestrogens was first noted to be associated with decreased incidences of certain diseases. This epidemiological data was obtained primarily from studying Asian populations. Soy consumption is highest in Japan, where urinary levels of phytoestrogen metabolites are extremely high and there are lower rates of so-called ‘Western’ diseases, including breast, endometrial, colon cancers as well as atherosclerotic disease. Research to date has focused on the antiproliferative potential of phytoestrogens, primarily genistein both in vitro and in vivo. Their role in the relief of menopausal symptoms, their hypocholesterolaemic effects and bone resorption protection have been investigated to some extent with promising results. A brief overview of the background of, and the research into, phytoestrogens will be provided in this article.

scholarly journals Effect of Ultraviolet C Irradiation on Isoflavone Concentrations in Different Cultivars of Soybean (Glycine max)

Plants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1043 ◽  
Author(s):  
Krishna Bahadur Karki ◽  
Awdhesh Kumar Mishra ◽  
Seong-Jin Choi ◽  
Kwang-Hyun Baek
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Dorsal Surface ◽  
Polyphenolic Compounds ◽  
Soy Isoflavones ◽  
Liquid Chromatography Mass Spectrometry ◽  
Naturally Occurring ◽  
Ultraviolet C ◽  
High Concentrations ◽  
Uv C

Phytoestrogens are naturally occurring plant polyphenolic compounds present in high concentrations in soybean products. Phytoestrogens are divided into three classes: lignans, isoflavones, and coumestans. Nine types of glycoside isoflavones and three types of aglycoside isoflavones are reported in soybean. Soy isoflavones can reduce the risk of a certain type of cancer, cardiovascular problems, osteoporosis, and menopausal symptoms. We irradiated the leaves of five cultivars of soybean with UV-C (260 nm) and determined the effect on concentrations of isoflavone compounds using liquid chromatography–mass spectrometry (LC–MS). Isoflavone concentrations were significantly higher following irradiation, particularly in the cultivar Daepung, which was selected as the best cultivar for high isoflavone induction with UV-C irradiation. Further experimentation with the cultivar Daepung revealed that 20 min UV-C irradiation was the best treatment for the induction of aglycone compounds, and 5 min with the dorsal surface facing the UV-C irradiation source was the best treatment for the induction of glycoside isoflavone compounds.

Studies on the action of interleukin-1 on term human fetal membranes and decidua

1994 ◽  
Vol 72 (2) ◽  
pp. 133-139 ◽  
Author(s):  
B. Alnaif ◽  
R. J. Benzie ◽  
W. Gibb
Keyword(s):  
Preterm Labor ◽  
Interleukin 1 ◽  
Fetal Membranes ◽  
Frozen Sections ◽  
Human Amnion ◽  
Chorion Laeve ◽  
Interleukin 1Α ◽  
Low Levels ◽  
High Concentrations ◽  
Dispersed Cells

Recent studies have indicated the possible importance of cytokines in the onset of term and preterm labor. To examine this further, the effect of interleukin-1β (IL-1β), interleukin-1α (IL-1α), and interleukin-6 (IL-6) on prostaglandin output by dispersed cells from human amnion, chorion laeve, and decidua obtained at term (38–40 weeks gestation) was examined. During the first or second 24 h of culture no significant effect of these interleukins on prostaglandin output was observed. The reason for this apparent refractoriness was further investigated by studying the distribution of IL-1 receptors in frozen sections of undisrupted fetal membranes and decidua at term. Whole-tissue autoradiography indicated that receptors were present in chorion–decidua but not in amnion. By using emulsion autoradiography, IL-1 receptors were found in high concentrations in chorion laeve and were absent in amnion and at low levels in the decidua. These studies indicate that under normal circumstances in human pregnancy at term IL-1 did not stimulate prostaglandin production by dispersed cells. In the case of amnion, this may be due to the absence of receptors, and therefore it would appear that the IL-1 receptor must first be induced in this tissue before it can respond to this cytokine. Furthermore, although chorion laeve expresses the IL-1 receptor, dispersed cells from this tissue did not respond to the cytokine by increasing prostaglandin output.Key words: labor, prostaglandins, interleukin-1, interleukin-1 receptor, fetal membranes, decidua.

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