Adhesion of biodegradative anaerobic bacteria to solid surfaces.
(9/517)
In order to exploit the ability of anaerobic bacteria to degrade certain contaminants for bioremediation of polluted subsurface environments, we need to understand the mechanisms by which such bacteria partition between aqueous and solid phases, as well as the environmental conditions that influence partitioning. We studied four strictly anaerobic bacteria, Desulfomonile tiedjei, Syntrophomonas wolfei, Syntrophobacter wolinii, and Desulfovibrio sp. strain G11, which theoretically together can constitute a tetrachloroethylene- and trichloroethylene-dechlorinating consortium. Adhesion of these organisms was evaluated by microscopic determination of the numbers of cells that attached to glass coverslips exposed to cell suspensions under anaerobic conditions. We studied the effects of the growth phase of the organisms on adhesion, as well as the influence of electrostatic and hydrophobic properties of the substratum. Results indicate that S. wolfei adheres in considerably higher numbers to glass surfaces than the other three organisms. Starvation greatly decreases adhesion of S. wolfei and Desulfovibrio sp. strain G11 but seems to have less of an effect on the adhesion of the other bacteria. The presence of Fe(3+) on the substratum, which would be electropositive, significantly increased the adhesion of S. wolfei, whereas the presence of silicon hydrophobic groups decreased the numbers of attached cells of all species. Measurements of transport of cells through hydrophobic-interaction and electrostatic-interaction columns indicated that all four species had negatively charged cell surfaces and that D. tiedjei and Desulfovibrio sp. strain G11 possessed some hydrophobic cell surface properties. These findings are an early step toward understanding the dynamic attachment of anaerobic bacteria in anoxic environments. (+info)
Novel vascular graft grown within recipient's own peritoneal cavity.
(10/517)
A method by which to overcome the clinical symptoms of atherosclerosis is the insertion of a graft to bypass an artery blocked or impeded by plaque. However, there may be insufficient autologous mammary artery for multiple or repeat bypass, saphenous vein may have varicose degenerative alterations that can lead to aneurysm in high-pressure sites, and small-caliber synthetic grafts are prone to thrombus induction and occlusion. Therefore, the aim of the present study was to develop an artificial blood conduit of any required length and diameter from the cells of the host for autologous transplantation. Silastic tubing, of variable length and diameter, was inserted into the peritoneal cavity of rats or rabbits. By 2 weeks, it had become covered by several layers of myofibroblasts, collagen matrix, and a single layer of mesothelium. The Silastic tubing was removed from the harvested implants, and the tube of living tissue was everted such that it now resembled a blood vessel with an inner lining of nonthrombotic mesothelial cells (the "intima"), with a "media" of smooth muscle-like cells (myofibroblasts), collagen, and elastin, and with an outer collagenous "adventitia." The tube of tissue (10 to 20 mm long) was successfully grafted by end-to-end anastomoses into the severed carotid artery or abdominal aorta of the same animal in which they were grown. The transplant remained patent for at least 4 months and developed structures resembling elastic lamellae. The myofibroblasts gained a higher volume fraction of myofilaments and became responsive to contractile agonists, similar to the vessel into which they had been grafted. It is suggested that these nonthrombogenic tubes of living tissue, grown in the peritoneal cavity of the host, may be developed as autologous coronary artery bypass grafts or as arteriovenous access fistulae for hemodialysis patients. (+info)
Antitumor effects of an interferon-loaded silicone formulation in human renal cell carcinoma in nude mice.
(11/517)
Conventional therapy for renal cell carcinoma using interferon (IFN) has shown limited antitumor action. The IFN-loaded silicone formulation (IFN-SF) is a sustained-release formulation of human lymphoblastoid IFN, with a medical grade silicone elastomer used as the carrier material. We evaluated the antitumor effect of IFN-SF on human renal cell carcinoma cell line (KU-2) transplanted to nude mice. The treatment was started when the tumor nodules had grown 6 to 8 mm in diameter. IFN-SF, on an aqueous solution of IFN, was given by subcutaneous or peritumoral injection. Antitumor effects were evaluated according to tumor weights calculated as (long diameter) x (short diameter)2/2 in 7 groups consisting of 6 mice each. Serum IFN levels remained detectable up to 30 days after subcutaneous injection of IFN-SF. IFN-SF administered by the subcutaneous and peritumor route significantly inhibited growth of the tumor when compared with tumor growth in the untreated mice and mice treated with aqueous IFN solution. IFN-SF had equivalent inhibitory effects on tumor growth by peritumor and subcutaneous injection. Results indicated that the use of IFN-SF could reduce the frequency of injections and provide better treatment of patients with renal cell carcinoma because of its long-acting effect when it is used systemically. (+info)
Use of solid-phase microextraction (SPME) for the determination of methadone and its main metabolite, EDDP, in plasma by gas chromatography-mass spectrometry.
(12/517)
A simple, rapid method for the determination of methadone and its metabolite 2-ethylene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in plasma using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry is proposed. A 100-microm polydimethylsiloxane film fiber was exposed by immersion for 30 min in a diluted plasma solution (1:4 with buffer pH 9) containing both compounds and an internal standard (proadifen). Calibration curves were linear over the concentration range 50-2000 ng/mL. The analysis time was 45 min per sample. The determination of methadone and EDDP was subject to no interference. The performance of SPME was compared with that of liquid-liquid extraction, obtaining lower limits of detection for EDDP. The method using the two extraction procedures was applied to 10 plasma samples from methadone-treated patients. (+info)
Patterned deposition of cells and proteins onto surfaces by using three-dimensional microfluidic systems.
(13/517)
Three-dimensional microfluidic systems were fabricated and used to pattern proteins and mammalian cells on a planar substrate. The three-dimensional topology of the microfluidic network in the stamp makes this technique a versatile one with which to pattern multiple types of proteins and cells in complex, discontinuous structures on a surface. The channel structure, formed by the stamp when it is in contact with the surface of the substrate, limits migration and growth of cells in the channels. With the channel structure in contact with the surface, the cells stop dividing once they form a confluent layer. Removal of the stamp permits the cells to spread and divide. (+info)
Coated bedpans: their cleaning and disinfection.
(14/517)
This paper reports on tests of cleaning and disinfection of stainless steel bedpans which have been coated with either a silicone grease or polytetrafluoroethylene (PTFE). The coatings were applied manually using an aerosol spray (silicone grease and PTFE), and by an industrial process (PTFE). Soils used comprised (i) British Standard Soil (B.S., 1966), (ii) human serum albumin labelled with technetium-99m (HSA-Tc), and (iii) a suspension of Streptococcus faecalis in broth. Tests of cleaning and disinfection were carried out in automatic washing and steam disinfector machines. Results show that aerosol spraying impairs the cleaning process but that bedpans coated by the industrial process with PTFE are superior to uncoated bedpans. (+info)
Microfabrication of an analog of the basal lamina: biocompatible membranes with complex topographies.
(15/517)
A microfabrication approach was used to produce novel analogs of the basal lamina with complex topographic features. A test pattern of ridges and channels with length scales (40 to 310 micrometer) similar to the invaginations found in a native basal lamina was laser machined into the surface of a polyimide master chip. Negative replicates of the chip were produced using polydimethylsiloxane silicone elastomer and these replicates were used as templates for the production of thin ( approximately 21 micrometer) membranes of collagen or gelatin. The resulting membranes had a complex topography of ridges and channels that recapitulated the features of the master chip. To demonstrate their utility, these complex membranes were laminated to type I collagen sponges and their surfaces were seeded with cultured human epidermal keratinocytes to form a skin equivalent. The keratinocytes formed a differentiated and stratified epidermis that conformed to the features of the microfabricated membrane. The topography of the membrane influenced the differentiation of the keratinocytes because stratification was enhanced in the deeper channels. Membrane topography also controlled the gross surface features of the skin equivalent; infolds of the epidermis increased as channel depth increased. These novel microfabricated analogs of the basal lamina will help to elucidate the influence of topography on epithelial cell proliferation and differentiation and should have applications in the tissue engineering of skin equivalents as well as other basal lamina-containing tissues. (+info)
Solid-phase microextraction in the determination of methadone in human saliva by gas chromatography-mass spectrometry.
(16/517)
Solid-phase microextraction (SPME) with a 100-microm polydimethylsiloxane film fiber was applied to the determination of methadone and 2-ethylidine-3,3-diphenylpyrrolidine (EDDP) by GC-MS in human saliva and compared with liquid-liquid extraction. A shorter extraction time of 30 min with the fiber was obtained, speeding up the total analysis time. Linearity was found for SPME from 0.05 to 2.0 microg/mL (r = 0.9976 for methadone; r = 0.9988 for EDDP) with precision between 0.7 and 4.3% for saliva spiked with 0.2 and 1.5 microg/mL of methadone and EDDP. The limit of detection using SPME was 0.04 microg/mL for methadone and 0.008 microg/mL for EDDP. Analytical recoveries of SPME and liquid-liquid extraction ranged from 98.8 to 103.6%. The use of deuterated internal standard by both methods have yielded comparable results. Thus, the SPME method is highly accurate, precise, and useful for determination of methadone and EDDP in saliva. (+info)