Medullary thyroid carcinoma with multiple hepatic metastases: treatment with transcatheter arterial embolization and percutaneous ethanol injection.
A 54-year-old man with medullary thyroid carcinoma in the thyroid gland was unable to undergo total thyroidectomy because the tumor had invaded the mediastinum. Radiation therapy and chemotherapy were given. Seven years later, intractable diarrhea and abdominal pain appeared, and computed tomography demonstrated hypervascular tumors in the thyroid gland and in the liver. The tumors were successfully treated with percutaneous ethanol injection to a lesion in the thyroid gland and transcatheter arterial embolization followed by percutaneous ethanol injection to tumors in the liver. Transcatheter arterial embolization and percutaneous ethanol injection may be valuable in treating medullary thyroid carcinoma. (+info)
Modulation of cell proliferation and differentiation through substrate-dependent changes in fibronectin conformation.
Integrin-mediated cell adhesion to extracellular matrices provides signals essential for cell cycle progression and differentiation. We demonstrate that substrate-dependent changes in the conformation of adsorbed fibronectin (Fn) modulated integrin binding and controlled switching between proliferation and differentiation. Adsorption of Fn onto bacterial polystyrene (B), tissue culture polystyrene (T), and collagen (C) resulted in differences in Fn conformation as indicated by antibody binding. Using a biochemical method to quantify bound integrins in cultured cells, we found that differences in Fn conformation altered the quantity of bound alpha5 and beta1 integrin subunits but not alphav or beta3. C2C12 myoblasts grown on these Fn-coated substrates proliferated to different levels (B > T > C). Immunostaining for muscle-specific myosin revealed minimal differentiation on B, significant levels on T, and extensive differentiation on C. Differentiation required binding to the RGD cell binding site in Fn and was blocked by antibodies specific for this site. Switching between proliferation and differentiation was controlled by the levels of alpha5beta1 integrin bound to Fn, and differentiation was inhibited by anti-alpha5, but not anti-alphav, antibodies, suggesting distinct integrin-mediated signaling pathways. Control of cell proliferation and differentiation through conformational changes in extracellular matrix proteins represents a versatile mechanism to elicit specific cellular responses for biological and biotechnological applications. (+info)
Can vector control play a useful supplementary role against bancroftian filariasis?
A single campaign of mass treatment for bancroftian filariasis with diethylcarbamazine (DEC) in Makunduchi, a town in Zanzibar, United Republic of Tanzania, combined with elimination of mosquito breeding in pit latrines with polystyrene beads was followed by a progressive decline over a 5-year period in the microfilarial rate from 49% to 3%. Evidence that vector control had contributed to this long-term decline was obtained by comparison with another town, Moga, where a DEC campaign was used without vector control and where resurgence of microfilariae could be observed 3-6 years after the campaign. In Zanzibar town, treatment of 3844 wet pit latrines and cesspits with polystyrene beads reduced the adult mosquito population in houses by about 65%. Supplementary treatment of open drains and marshes with Bacillus sphaericus produced little or no additional reduction compared to a sector of the town where only pit treatment with polystyrene was carried out. The cost and effort of achieving the 65% reduction in mosquito population could hardly be justified for its impact on filariasis alone, but its noticeable impact on biting nuisance might help to gain community support for an integrated programme. (+info)
Defensins impair phagocytic killing by neutrophils in biomaterial-related infection.
The implantation of foreign material carries a risk of infection which frequently is resistant to all treatment short of removing the implant. We have previously shown that these materials activate neutrophils by contact, leading to production of oxygen free radicals accompanied by release of granule products. Such activation further results in depletion of local host defenses, including the capacity of biomaterial-activated neutrophils to kill bacteria. Among the granule products released from neutrophils are small cationic antibacterial peptides (human neutrophil peptides [HNP]) known as defensins. Here we tested the hypothesis that defensins, released from activated neutrophils onto the surface of biomaterials, might play a role in the deactivation of subsequent neutrophil populations. Incubation of neutrophils with purified HNP resulted in a dose-related impairment of stimulus-induced oxygen radical production and of phagocytic killing. Furthermore, fresh neutrophils added to biomaterial-associated neutrophils exhibited impaired phagocytic killing. This impairment could be abrogated by antibody to HNP but not by an irrelevant antibody. Taken together, these observations support the idea that neutrophils activated at a material surface can create, by means of HNP release, an environment hostile to their microbicidal function and that of their infiltrating brethren. (+info)
Quantitative analysis of styrene monomer in polystyrene and foods including some preliminary studies of the uptake and pharmacodynamics of the monomer in rats.
A variety of food containers, drinking cups and cutlery, fabricated from polystyrene (PS) or polystyrene-related plastic, were analyzed for their styrene monomer content. Samples of yogurt, packaged in PS cups, were similarly analyzed and the leaching of styrene monomer from PS containers by some food simulants was also determined. Blood level studies with rats, dosed with styrene monomer by various routes, illustrated uptake phenomena that were dependent on the dose and route of administration and were also affected by the vehicle used to convey the styrene monomer. (+info)
Protein adhesion force dynamics and single adhesion events.
Using the manipulation force microscope, a novel atomic force microscope, the adhesion forces of bovine serum albumin, myoglobin, ferritin, and lysozyme proteins to glass and polystyrene substrates were characterized by following the force necessary to displace an adsorbed protein-covered microsphere over several orders of magnitude in time. This force was consistent with a power law with exponent a = 0.37 +/- 0.03 on polystyrene, indicating that there is no typical time scale for adhesion on this substrate. On glass, the rate of adhesion depended strongly on protein charge. Forces corresponding to single protein adhesion events were identified. The typical rupture force of a single lysozyme, ferritin, bovine serum albumin, and myoglobin protein adhering to glass was estimated to be 90 +/- 10 pN, 115 +/- 13 pN, 277 +/- 44 pN, and 277 +/- 44 pN, respectively, using a model of the experimental system. These forces, as well as the force amplitudes on hydrophobic polystyrene, correlate with protein stiffness. (+info)
RecA polymerization on double-stranded DNA by using single-molecule manipulation: the role of ATP hydrolysis.
The polymerization of RecA on individual double-stranded DNA molecules is studied. A linear DNA (lambda DNA, 48.5 Kb), anchored at one end to a cover glass and at the other end to an optically trapped 3-micrometers diameter polystyrene bead, serves as a template. The elongation caused by RecA assembly is measured in the presence of ATP and ATP[gammaS]. By using force extension and hydrodynamic recoil, a value of the persistence length of the RecA-DNA complex is obtained. In the presence of ATP, the polymer length is unstable, first growing to saturation and then decreasing. This suggests a transient dynamics of association and dissociation for RecA on a double-stranded DNA, the process being controlled by ATP hydrolysis. Part of this dynamics is suppressed in the presence of ATP[gammaS], leading to a stabilized RecA-DNA complex. A one-dimensional nucleation and growth model is presented that may account for the protein assembly. (+info)
Spore surface glycoproteins of Colletotrichum lindemuthianum are recognized by a monoclonal antibody which inhibits adhesion to polystyrene.
Conidia (spores) of Colletotrichum lindemuthianum, a fungal plant pathogen causing bean anthracnose, adhere to the aerial parts of host plants to initiate the infection process. These spores possess a fibrillar 'spore coat' as well as a cell wall. In a previous study a mAb, UB20, was raised that recognized glycoproteins on the spore surface. In this study UB20 was used to localize and characterize these glycoproteins and to investigate their possible role in adhesion. Glycoproteins recognized by UB20 were concentrated on the outer surface of the spore coat and, to a lesser extent, at the plasma membrane/cell wall interface. Extraction of spores with hot water or 0.2% SDS resulted in removal of the spore coat. Western blotting with UB20 showed that a relatively small number of glycoproteins were extracted by these procedures, including a major component at 110 kDa. Biotinylation of carbohydrate moieties, together with cell fractionation, confirmed that these glycoproteins were exposed at the surface of the spores. In adhesion assays, > 90% of ungerminated conidia attached to polystyrene Petri dishes within 30 min. UB20 IgG at low concentrations inhibited attachment in an antigen-specific manner. This suggests that the glycoproteins recognized by this mAb may function in the initial rapid attachment of conidia to hydrophobic substrata. Polystyrene microspheres bound selectively to the 110 kDa glycoprotein in Western blots, providing further evidence that this component could mediate interactions with hydrophobic substrata. (+info)