scholarly journals Fabrication and Characteristics of Chitosan Sponge as a Tissue Engineering Scaffold

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Takeshi Ikeda ◽  
Kahori Ikeda ◽  
Kouhei Yamamoto ◽  
Hidetaka Ishizaki ◽  
Yuu Yoshizawa ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Porous Scaffold ◽  
Chitosan Solution ◽  
Spongiform Encephalopathy ◽  
Porous Chitosan ◽  
Chitosan Scaffolds ◽  
Controlled Freezing ◽  
The Relationship ◽  
Releasing Time

Cells, growth factors, and scaffolds are the three main factors required to create a tissue-engineered construct. After the appearance of bovine spongiform encephalopathy (BSE), considerable attention has therefore been focused on nonbovine materials. In this study, we examined the properties of a chitosan porous scaffold. A porous chitosan sponge was prepared by the controlled freezing and lyophilization of different concentrations of chitosan solutions. The materials were examined by scanning electron microscopy, and the porosity, tensile strength, and basic fibroblast growth factor (bFGF) release profiles from chitosan sponge were examined in vitro. The morphology of the chitosan scaffolds presented a typical microporous structure, with the pore size ranging from 50 to 200 μm. The porosity of chitosan scaffolds with different concentrations was approximately 75–85%. A decreasing tendency for porosity was observed as the concentration of the chitosan increased. The relationship between the tensile properties and chitosan concentration indicated that the ultimate tensile strength for the sponge increased with a higher concentration. The in vitro bFGF release study showed that the higher the concentration of chitosan solution became, the longer the releasing time of the bFGF from the chitosan sponge was.

scholarly journals Lysozyme-Induced Degradation of Chitosan: The Characterisation of Degraded Chitosan Scaffolds

2017 ◽  
Vol 1 (1) ◽  
pp. 12-22 ◽  
Author(s):  
Andrea Lončarević ◽  
Marica Ivanković ◽  
Anamarija Rogina
Keyword(s):  
Drug Delivery ◽  
Weight Loss ◽  
Enzymatic Degradation ◽  
Gravimetric Analysis ◽  
Degradation Behaviour ◽  
Porous Chitosan ◽  
Before And After ◽  
Glycoside Bond ◽  
Chitosan Scaffolds

Up till now, chitosan has confirmed its versatile application in skin, cartilage and bone tissue engineering, as well as in drug delivery applications. This study is focused on enzymatic degradation of porous chitosan structures usually designed for mentioned purposes. In vitro degradation was monitored during four weeks of incubation at physiological temperature and in two different media, phosphate buffer saline solution and water. The scaffolds were characterised before and after enzymatic degradation using scanning electron microscopy and infrared spectroscopy with Fourier transformations (FTIR). According to the gravimetric analysis, higher weight loss of chitosan scaffolds was observed in buffered medium with respect to the water. The results implied that the total weight loss obtained in buffer involves physical dissolution of chitosan and lysozyme cleavage of glycoside bond. Importantly, FTIR identification of chitosan scaffolds after enzymatic degradation indicated the absence of lysozyme activity in water, indicating that weight loss is a result of the chitosan dissolution. This finding greatly impacts design of degradation experiments and characterisation of degradation behaviour of chitosan-based materials utilised as implants or drug delivery systems.

scholarly journals PrPSc with Seeding Activity Extensively Overlaps with Proteinase-Resistant PrPSc Rather than Infectious PrPSc

Pathogens ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 241 ◽  
Author(s):  
Yoshifumi Iwamaru ◽  
Yuichi Matsuura ◽  
Kohtaro Miyazawa
Keyword(s):  
Spongiform Encephalopathy ◽  
Prion Infection ◽  
Infectious Titer ◽  
Stage Disease ◽  
Amplification Assay ◽  
End Stage ◽  
Dose Levels ◽  
The Relationship ◽  
Conformational Conversion

The disease-associated prion protein (PrPSc) has the ability to seed the conformational conversion of normal prion proteins into the amyloid fibril form. This prion seeding activity can be measured using an in vitro amplification assay termed real-time quaking-induced conversion (RT-QuIC). There is a strong correlation between RT-QuIC positivity and prion infection; however, the relationship between seeding activity and infectivity remains elusive. In this study, we used endpoint dilution RT-QuIC on the brain homogenates from wild-type mice with mouse-adopted bovine spongiform encephalopathy (mBSE) at defined intervals during the incubation period and evaluated the temporal relationship among prion seeding dose, levels of proteinase-resistant PrPSc (PrPres), and infectious titer. We found that the infectious titer reached a plateau by 100 days postinfection, whereas seeding dose and PrPres levels were continuously elevated. Our calculation showed that the doubling time (dt) for seeding dose from 40 to 100 days postinoculation was closer to the dt for PrPres levels than to the dt for prion titer. Although an uncoupling of seeding doses and PrPres levels was observed at end-stage disease in this model, our findings suggest that there is substantial but not complete overlap between PrPSc with seeding activity and PrPres rather than infectious PrPSc.

scholarly journals Preliminary In Vitro Evaluation of Chitosan–Graphene Oxide Scaffolds on Osteoblastic Adhesion, Proliferation, and Early Differentiation

2020 ◽  
Vol 21 (15) ◽  
pp. 5202 ◽  
Author(s):  
Sonia How Ming Wong ◽  
Siew Shee Lim ◽  
Timm Joyce Tiong ◽  
Pau Loke Show ◽  
Hayyiratul Fatimah Mohd Zaid ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Graphene Oxide ◽  
Cell Adhesion ◽  
Chitosan Solution ◽  
Early Differentiation ◽  
Chitosan Matrix ◽  
Chitosan Scaffolds ◽  
Diphenyl Tetrazolium Bromide ◽  
Differentiation Marker

An ideal scaffold should be biocompatible, having appropriate microstructure, excellent mechanical strength yet degrades. Chitosan exhibits most of these exceptional properties, but it is always associated with sub-optimal cytocompatibility. This study aimed to incorporate graphene oxide at wt % of 0, 2, 4, and 6 into chitosan matrix via direct blending of chitosan solution and graphene oxide, freezing, and freeze drying. Cell fixation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, alkaline phosphatase colorimetric assays were conducted to assess cell adhesion, proliferation, and early differentiation of MG63 on chitosan–graphene oxide scaffolds respectively. The presence of alkaline phosphatase, an early osteoblast differentiation marker, was further detected in chitosan–graphene oxide scaffolds using western blot. These results strongly supported that chitosan scaffolds loaded with graphene oxide at 2 wt % mediated cell adhesion, proliferation, and early differentiation due to the presence of oxygen-containing functional groups of graphene oxide. Therefore, chitosan scaffolds loaded with graphene oxide at 2 wt % showed the potential to be developed into functional bone scaffolds.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Plasminogen Depletion during Streptokinase Treatment or Two-Chain Urokinase Incubation Correlates with Decreased Clot Lysability Ex Vivo and In Vitro

1993 ◽  
Vol 70 (06) ◽  
pp. 0998-1004 ◽  
Author(s):  
Páll T Önundarson ◽  
H Magnús Haraldsson ◽  
Lena Bergmann ◽  
Charles W Francis ◽  
Victor J Marder
Keyword(s):  
Myocardial Infarction ◽  
Ex Vivo ◽  
Time Dependent ◽  
State Variables ◽  
Thrombolytic Treatment ◽  
Direct Proportion ◽  
Plasmin Activity ◽  
Plasma Exposure ◽  
The Relationship

SummaryThe relationship between lytic state variables and ex vivo clot lysability was investigated in blood drawn from patients during streptokinase administration for acute myocardial infarction. A lytic state was already evident after 5 min of treatment and after 20 min the plasminogen concentration had decreased to 24%, antiplasmin to 7% and fibrinogen 0.2 g/1. Lysis of radiolabeled retracted clots in the patient plasmas decreased from 37 ± 8% after 5 min to 21 ± 8% at 10 min and was significantly lower (8 ± 9%, p <0.005) in samples drawn at 20, 40 and 80 min. Clot lysability correlated positively with the plasminogen concentration (r = 0.78, p = 0.003), but not with plasmin activity. Suspension of radiolabeled clots in normal plasma pre-exposed to 250 U/ml two-chain urokinase for varying time to induce an in vitro lytic state was also associated with decreasing clot lysability in direct proportion with the duration of prior plasma exposure to urokinase. The decreased lysability correlated with the time-dependent reduction in plasminogen concentration (r = 0.88, p <0.0005). Thus, clot lysability decreases in conjunction with the development of the lytic state and the associated plasminogen depletion. The lytic state may therefore limit reperfusion during thrombolytic treatment.

Monitoring Anticoagulant Therapy by Activated Partial Thromboplastin Time: Hirudin Assessment

1994 ◽  
Vol 72 (05) ◽  
pp. 685-692 ◽  
Author(s):  
Michael T Nurmohamed ◽  
René J Berckmans ◽  
Willy M Morriën-Salomons ◽  
Fenny Berends ◽  
Daan W Hommes ◽  
...  
Keyword(s):  
Whole Blood ◽  
Partial Thromboplastin Time ◽  
Ex Vivo ◽  
Fold Increase ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Recombinant Hirudin ◽  
Interindividual Differences ◽  
The Relationship

SummaryBackground. Recombinant hirudin (RH) is a new anticoagulant for prophylaxis and treatment of venous and arterial thrombosis. To which extent the activated partial thromboplastin time (APTT) is suitable for monitoring of RH has not been properly evaluated. Recently, a capillary whole blood device was developed for bed-side monitoring of the APTT and it was demonstrated that this device was suitable to monitor heparin therapy. However, monitoring of RH was not evaluated.Study Objectives. To evaluate in vitro and ex vivo the responsiveness and reproducibility for hirudin monitoring of the whole blood monitor and of plasma APTT assays, which were performed with several reagents and two conventional coagulometers.Results. Large interindividual differences in hirudin responsiveness were noted in both the in vitro and the ex vivo experiments. The relationship between the APTT, expressed as clotting time or ratio of initial and prolonged APTT, and the hirudin concentration was nonlinear. A 1.5-fold increase of the clotting times was obtained at 150-200 ng/ml plasma. However, only a 2-fold increase was obtained at hirudin levels varying from 300 ng to more than 750 ng RH/ml plasma regardless of the assays. The relationship linearized upon logarithmic conversion of the ratio and the hirudin concentration. Disregarding the interindividual differences, and presuming full linearity of the relationship, all combinations were equally responsive to hirudin.Conclusions. All assays were equally responsive to hirudin. Levels up to 300 ng/ml plasma can be reliably estimated with each assay. The manual device may be preferable in situations where rapid availability of test results is necessary.

SINTESIS DAN MODIFIKASI STRUKTUR DAN PORI MEMBRAN KITOSAN TERCROSSLINK UNTUK STERILISASI MEDIA PERTUMBUHAN BAKTERI

2019 ◽  
Vol 3 (2) ◽  
pp. 27
Author(s):  
Emma Savitri ◽  
Natalia Suseno ◽  
Tokok Adiarto
Keyword(s):  
Tensile Strength ◽  
Chitosan Solution ◽  
Curing Temperature ◽  
Growth Media ◽  
Optimum Conditions ◽  
Separation Processes ◽  
Crosslinking Process ◽  
Chitosan Membrane ◽  
Chitosan Membranes ◽  
Crosslinked Chitosan

Many mass-transfer applications have used chitosan membrane in separation processes. This research applied crosslinked chitosan membrane to sterillize bacterial growth media. Chitosan membranes having 79 % DD were produced by casting and drying chitosan solution. The images of the membrane were characterized by SEM and other characterizations such as permeability, permselectivity and tensile strength were investigated. The flux increased with longer submersion period but the rejection decreased. Otherwise, the flux decreased and rejection increased in line with an increase in curing temperature. Tensile strength increased with the increase of submersion period and curing temperature. The optimum conditions of crosslinking process are 2 hours of submersion periods and curing temperature at 90 oC.  It gives flux 5.8930 L/jam.m2, rejection 97.47 % and tensile strength 49640 kN/m2

Formulation and Evaluation of Chitosan-Polyaniline Nanocomposites for Controlled Release of Anticancer Drug Doxorubicin

2018 ◽  
Vol 8 (2) ◽  
Author(s):  
Dillip Kumar Behera ◽  
Kampal Mishra ◽  
Padmolochan Nayak
Keyword(s):  
Tensile Strength ◽  
Drug Release ◽  
Nanocomposite Films ◽  
Casting Method ◽  
Sustained Drug Release ◽  
In Vitro Drug Release ◽  
Clay Particles ◽  
Solution Casting Method ◽  
Nanoclay Content

In this present work, chitosan (CS) crosslink with polyaniline (PANI) with montmorilonite (MMT) called as (CSPANI/MMT) and CS crosslink with PANI without MMT called as (CS-PANI) were prepared by employing the solution casting method. Further the formation of nanocomposites CS-PANI/MMT and CS-PANI were investigated using XRD, FTIR, SEM and tensile strength. Water uptake and swelling ratio of the CS-PANI and CS-PANI/MMT were found to decrease with increase in concentration of clay. Mechanical properties of the CS-PANI and CS-PANI/MMT were assessed in terms of tensile strength and extensibility using texture analyzer. Increase in tensile strength and reduction in extensibility was reported with increase in the nanoclay content. In vitro drug release study on CS-PANI and CS-PANI/MMT indicated pronounced sustained release of doxorubicin by the incorporation of clay particles in the CS polymer matrix. Overall CSPANI/MMT nanocomposite films exhibited improved mechanical and sustained drug release properties than CS-PANI.

Thickness of endometrium: predictor of the effectiveness of IVF/ICSI programs (literature review)

GYNECOLOGY ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 113-116
Author(s):  
L A Bagdasaryan ◽  
I E Korneyeva
Keyword(s):  
Assisted Reproductive Technologies ◽  
Endometrial Thickness ◽  
Molecular Genetic ◽  
Uterine Cavity ◽  
Reproductive Technologies ◽  
Genetic Characteristics ◽  
Vitro Fertilization ◽  
Need To Evaluate ◽  
The Relationship

The aim of the study is to systematically analyze the data available in the modern literature on the relationship between endometrial thickness and the frequency of pregnancy in the program of assisted reproductive technologies (ART). Materials and methods. The review includes data from foreign and domestic articles found in PubMed on this topic. Results. The article presents data on the relationship between the thickness of the endometrium and the frequency of pregnancy in ART programs. The greatest number of studies is devoted to the evaluation of the relationship between the thickness of the endometrium and the frequency of pregnancy on the day of the ovulation trigger. Data are presented on the existence of a correlation between the thickness of the endometrium measured on the day of the ovulation trigger and the frequency of clinical pregnancy, as well as data on the need to evaluate the structure of the endometrium and the state of subendometric blood flow. The importance of multilayered (three-layered) endometrium as a prognostic marker of success in in vitro fertilization/intracytoplasmic sperm injection programs in the ovum is emphasized. The conclusion. The thickness of the endometrium can not be used as an argument for canceling the cycle or abolishing embryo transfer to the uterine cavity. Further studies in this direction are needed with a study of the morphological and molecular genetic characteristics of the endometrium, which in the future will allow us to evaluate the relationship between the thickness of the endometrium and the probability of pregnancy.

Sign in / Sign up

Export Citation Format

Share Document