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GS Ashcroft MA Horan SE Herrick RW Tarnuzzer GS Schultz MW Ferguson 《Canadian Metallurgical Quarterly》1997,290(3):581-591
Despite the association of increasing age with chronic wound-healing disorders and an impaired rate of healing of acute cutaneous wounds, the role of matrix metalloproteinases (MMPs) is unknown. To determine the spatial and temporal patterns and activities of MMP-1, -2, -3 and -9, 132 healthy humans aged between 19 and 96 years underwent 4-mm punch biopsies followed by wound excision between day 1 and day 180 post-wounding. Wounds showed an age-related increase in MMP-2 and MMP-9 immunostaining from day 3; this was associated with degradation of gelatin as shown by zymograms and with increased proteinase activity as shown by azocoll assays. Distinct spatial localisations for each MMP were observed: MMP-2 was found in epidermal structures; MMP-9 was observed in inflammatory cells up to day 21; MMP-1 was localised to keratinocytes at the wound margin. Normal old skin showed pro-MMP-2 bands on zymography and increased MMP-2 immunostaining. These results indicate that: (1) intrinsic ageing is associated with the up-regulation of MMPs previously associated with chronic wound healing; (2) wound-tissue proteinases are essentially active up to day 21 postwounding; and (3) intrinsic ageing may predispose to tissue breakdown disorders because of MMP-2 up-regulation in normal skin. 相似文献
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A 31-year-old female was found dead with 18 nicotine transdermal system patches taped to her upper body and a plastic bag taped over her nose and mouth (the cause of death was ruled asphyxiation). Nicotine concentrations in biological fluids and tissues were analyzed using a liquid-liquid extraction followed by injection onto and HP-5890 gas chromatograph (GC) equipped with a nitrogen-phosphorus detector. Cotinine was separated from the biological matrices using solid-phase extraction followed by analysis on an HP-5890 GC with flame ionization detection. A variety of specimens were analyzed, including blood, urine, vitreous, brain, liver, and gastric contents. Heart and femoral blood concentrations (1.4 and 0.46 micrograms/mL, respectively) were 175 and 57 times, respectively, the mean C(max) value reported following the proper administration of a single 7-mg/day patch. 相似文献
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GS Kim SH Kim JK Cho JY Park MJ Shin YK Shong KU Lee H Han TG Kim SL Teitelbaum WR Reinus MP Whyte 《Canadian Metallurgical Quarterly》1997,76(3):157-169
Pancreatic cancer is an aggressive disease with a dismal prognosis. It has long been regarded as one of the most difficult cancers to accurately diagnose and stage preoperatively. The purpose of this review is to provide an update of the state-of-the-art for early detection, diagnosis, and staging of pancreatic cancer. These methods include spiral CT scans, magnetic resonance imaging, positron emission tomography (PET) imaging, laparoscopy, endoscopic ultrasound, CA 19-9 serology, fine needle aspiration cytology, ERCP brush cytology, and screening for p53 and ras oncogenes. These advanced techniques should help us to detect pancreatic cancers in high-risk populations at a curative stage and to decrease pancreaticoduodenectomies for benign disease which could otherwise be treated with less morbid procedures. In addition, these tests will help reliably diagnose pancreatic cancer preoperatively. 相似文献
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Laser Doppler flowmetry was used intraoperatively to monitor femoral head perfusion during open reduction of 13 congenital hip dislocations in 11 patients. Laser Doppler determinations ranged from 12 to 400 mV before reduction and 30 to 300 mV after reduction. Three patients had magnitude changes in excess of 50%. One had increased perfusion, and two had decreased blood flow. Avascular necrosis of the hip occurred in one patient that was not predicted by laser Doppler flowmetry. Femoral head perfusion measured 175 mV for the dislocated hip and 180 mV after reduction of the femoral head and completion of the pelvic osteotomy. The authors conclude that laser Doppler flowmetry is not a reliable method for monitoring femoral head perfusion during open reduction of the hip for developmental hip dysplasia. 相似文献
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Narendra Reddy;Vijaykumar Guna;Nagananda GS;Supritha Muppuri;Pornanong Aramwit; 《Biofuels, Bioproducts and Biorefining》2024,18(1):113-124
We present a simple approach to convert coconut (copra) oil cake into biothermoplastics with properties that are suitable for replacing synthetic polymer-based plastics in current use. About 1.9 million tons of copra meal are generated ever year as coproducts and are available at $0.50–$0.60 per kilogram, making it a renewable, sustainable and low-cost raw material. Despite containing proteins, carbohydrates and oil, there are limited non-food applications of oil meals since most oil meals are typically non-thermoplastic and hence difficult to be processed into bioproducts. In this study, we report the processing of copra meal into biothermoplastics in the presence of various plasticizers, heat and pressure. Compression molded films and bioproducts were developed from copra meal by heating at 130°C in the presence of glycerol, coconut oil or cashew shell oil as plasticizer. The films obtained had tensile strength of up to 4.4 MPa and were inherently stable in water. A one-step crosslinking with citric acid was done to further improve the strength and stability of the films. With large availability at low cost, copra meal provides an opportunity to develop low-cost, biodegradable, edible and innovative bioproducts that have the potential to replace the synthetic polymer-based plastics in current use, particularly single-use plastics. 相似文献
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Sourav Barik;Mayureshwar Sunil Konarde;Aswathy NR;Sudha GS;Arpita A. Pattnaik;Aswini Kumar Mohapatra; 《Polymer Composites》2024,45(12):11200-11211
Bacterial biopolymers are polymeric materials that are produced by microorganisms. Due to its inherent brittleness and slow crystallization rate, it has limited industrial applications. Polyhydroxybutyrate (PHB) composites have been created to tackle these problems by combining non-modified clay and organically modified nanoclay. In this study, 3 wt % of two different kinds of clays were incorporated to PHB through melt mixing method to prepare composites of PHB/bentonite Clay (BC) and PHB/organically modified nanoclay (Cloisite 30B (C30B)). The characteristics of PHB and its composites were investigated to study their thermal, rheological, morphological, surface properties and biodegradability. The study showed that the incorporation of C30B and BC into the PHB matrix improved the crystallization temperature to 97.30 and 96.82°C respectively as compared to the crystallization temperature of the PHB matrix as 88.79°C. The increased result of storage modulus (G') and loss modulus (G\") in its rheological analysis confirmed that there was proper melt intercalation in case of both PHB/C30B and PHB/BC composite. The morphological characteristics results provide less coagulation and good clay distribution over the polymer matrix which leads to improved contact angle of 66.60° and 68.15° in case of PHB/BC and PHB/C30B respectively. Further both the composites and PHB film showed biodegradation characteristics. In the realm of nanocomposite films for various applications, where the cost is the major consideration, the PHB/BC composite films are promising economical solution in place of high cost PHB/C30B nanocomposite films. 相似文献
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