Browsing by Subject "freeze drying"

Now showing 1 - 4 of 4
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    Evaluation of the Effects of Different Biomaterials on Bone Defects
    (Lippincott Williams and Wilkins, 2000) Dalkýz M.; Ozcan A.; Yapar M.; Gökay N.; Yüncü M.
    Studies concerning natural and synthetic graft materials that have been used in different medical procedures have focused on freeze-dried bone, coral, hydroxylapatite, and tricalcium phosphate. This study histologically investigates the effects of these materials on the healing of bone defects. The experiments were performed on 30 albino rabbits. Cavities were drilled in the posterior right tibias of rabbits and were filled with coral, freeze-dried bone, hydroxylapatite, or calcium hydroxide. One cavity was left unfilled as a control. The bone in which the materials were implanted was excised at 7, 15, 30, 45, and 60 days. After the histological staining procedures, the prepared materials were observed using a light microscope. Although all materials showed good bone remodeling at the end of 60 days, coral and hydroxylapatite materials could be seen in the bone structure. The most effective materials within bone defect improvement were freeze-dried bone and calcium hydroxide.
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    Serum hepatitis B DNA: Stability in relation to multiple freeze-thaw procedures
    (2005) Sanlidag T.; Akcali S.; Ozbakkaloglu B.
    Quantitation of hepatitis B virus (HBV) DNA is often performed in specimens that have been frozen and thawed more than once. It is important to establish whether viral load measurements are affected by repeated freeze-thaw cycles. The effect of multiple freeze-thaw cycles on HBV DNA quantitation was carried out by testing serum specimens subjected to 1 (baseline) to 10 cycles with the appropriate Digene Hybrid Capture System. Five HBV DNA-positive samples were selected at random from sera with concentrations ranging from 7 pg/ml to 3529 pg/ml and they were frozen and thawed up to 10 cycles and then tested for changes in HBV DNA levels. Negative control and positive standards were tested in triplicate; and all specimens were tested in duplicate. The stability of HBV DNA in serum was evaluated by scattergram analysis by determining the number of samples showing a ≥20% change in HBV DNA levels after freeze-thaw cycles. With the exception of one sample (7 pg/ml) 10 cycles of freezing and thawing did not change significantly the HBV DNA quantity in any of the samples tested. The results showed that the quantity of HBV DNA in four of five serum specimens subjected up to 10 freeze-thaw cycles was stable. © 2004 Elsevier B.V. All rights reserved.
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    Gamma scintigraphy and biodistribution of 99mTc-cefotaxime sodium in preclinical models of bacterial infection and sterile inflammation
    (John Wiley and Sons Ltd, 2016) Ilem-Ozdemir D.; Asikoglu M.; Ozkilic H.; Yilmaz F.; Hosgor-Limoncu M.; Ayhan S.
    99mTc-cefotaxime sodium (99mTc-CEF) was developed and standardized under varying conditions of reducing and antioxidant agent concentration, pH, radioactivity dose, and reducing agent type. Labeling studies were performed by changing the selected parameters one by one, and optimum labeling conditions were determined. After observing the conditions for maximum labeling efficiency and stability, lyophilized freeze dry kits were prepared accordingly. Simple method for radiolabeling of CEF with 99mTc has been developed and standardized. Labeling efficiency of 99mTc-CEF was assessed by both radio thin-layer chromatography and radio high-performance liquid chromatography and found higher than 90%. The labeled compound was found to be stable in saline and human serum up to 24 h. Two different freeze dry kits were developed and evaluated. Based on the data obtained from this study, both products were stable for 6 months with high labeling efficiency. The prepared cold kit was found sterile and pyrogen free. The bacterial infection and sterile inflammation imaging capacity of 99mTc-CEF was evaluated. Based on the in vivo studies, 99mTc-CEF has higher uptake in infected and inflamed thigh muscle than healthy thigh muscle. Cefotaxime sodium (CEF) was successfully labeled with 99mTc from newly developed instant kit. Radiochemical purity was found greater than 90% and the labeled compound was stable in human serum during incubation period up to 24 h. The improved kit was found to be sterile, pyrogen free and stable up to 6 months. According to gamma scintigraphy studies, 99mTc-CEF showed a higher uptake in bacterial infected and sterile inflamed muscle than healthy thigh muscle. © Copyright 2016 John Wiley & Sons, Ltd.
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    Topical systems for the controlled release of antineoplastic Drugs: Oxidized Alginate-Gelatin Hydrogel/Unilamellar vesicles
    (Academic Press Inc., 2023) Stagnoli S.; Garro C.; Ertekin O.; Heid S.; Seyferth S.; Soria G.; Mariano Correa N.; Leal-Egaña A.; Boccaccini A.R.
    The efficacy of chemotherapeutic procedures relies on delivering proper concentrations of anti-cancer drugs in the tumor surroundings, so as to prevent potential side effects on healthy tissues. Novel drug carrier platforms should not just be able to deliver anticancer molecules, but also allow for adjustements in the way these drugs are administered to the patients. We developed a system for delivering water-insoluble drugs, based on the use of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), or bis(2-ethylhexyl) sulfosuccinate benzyl-n-hexadecyldimethylammonium (BHD-AOT), embedded into oxidized alginate-gelatin (ADA/Gel) hydrogel, emulating a patch for topic applications. After being loaded with curcumin, cancer cells such as human colorectal adenocarcinoma (HCT116 and DLD-1) and melanoma cell lines (MEL501), and non-malignant cells such as mammary epithelial cell lines (NMuMG) and embryonal fibroblasts (NIH 3T3 or NEO cells) were analyzed for biocompatibility and cytotoxic effects. The results show that the proposed system can load comparatively higher concentrations of the drug (with respect to other nano/microcarriers in the literature), and that it can enhance the likelihood of the drug being uptaken by cancer cells instead of non-malignant cells. These assays were complemented by diffusion studies across the stratum corneum of rat skin, with the aim of determining the system's efficiency during topical application. Finally, the stability of the patch was tested after lyophilization to determine its potential pharmaceutical use. As a whole, the combined system represents a highly reliable and robust method for embedding and delivering complex insoluble chemotherapeutical molecules, and it is less invasive than other alternative methods in the literature. © 2022 Elsevier Inc.