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 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The uptake of serum albumin by maturation-stage rodent enamel and the resulting effects on the growth of enamel crystallites were investigated in vitro. Albumin uptake was demonstrated by means of gel electrophoresis and confirmed by Western blotting with use of monoclonal antibodies. Measurement of crystal size was carried out by direct TEM measurement of enamel crystallite outlines after incubations in metastable solutions of calcium phosphate. The ability of endogenous enamel enzymes to degrade albumin was investigated by substrate-specific zymography. The results showed that albumin could be taken up by maturation-stage enamel and produce inhibition of crystallite growth. There was no detectable proteolytic activity in the enamel against albumin substrate, which suggests that albumin entering enamel by extravasation in vivo may produce incomplete tissue maturation, resulting in a white, opaque appearance on eruption.
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PMID:The role of albumin in developing rodent dental enamel: a possible explanation for white spot hypoplasia. 131 35

Complement-activating bovine serum albumin (BSA)-anti-BSA immune complexes (ICs) were injected into rabbit knee joint cavities; the contralateral control joint was injected with BSA together with normal rabbit serum. The migration of leukocytes from the synovial venules into the joint cavity was analyzed with light microscopy (LM), scanning (SEM) and transmission (TEM) electron microscopy. EM autoradiography was used to study the endocytosis of ICs by leukocytes. The shape, orientation, and distribution of migrating polymorphonuclear granulocytes (PMNGs) were analyzed by LM morphometry. PMNGs accumulated in the joints injected with ICs. The peak of the number of PMNGs in the synovial tissue was reached after 4 hours, in the joint cavity after 6 hours. PMNGs in the synovial tissue were concentrated in the intimal layer. Migrating PMNGs were polarized, as judged by the ratio between the long (D max) and short (D min) axes of the cells. There was a close association between the migrating PMNGs and the collagen fibers. The morphometric data showed that the nonflattened, cylindrically-shaped PMNGs were oriented along the collagen bundles, running parallel to the synovial surface, and did not migrate in the straight direction of a theoretic leukotactic gradient originating in the joint cavity after IC deposition. SEM and TEM showed that the PMNGs were aligned along the collagen fibers and interacted activity with the collagen by pseudopods and cytoplasmic projections. EM autoradiography showed that the PMNGs in the joint cavity had ingested 125I-labeled ICs and were degranulated. In contrast, the PMNGs within the synovial membrane did not show any signs of IC endocytosis or any apparent degranulation. Synovial type A cells were found to contain ICs. This study indicates that the response of PMNGs in IC-induced synovitis consists of two distinct phases: an initial, mainly migratory phase in the synovial membrane where the PMNGs appear to use the collagen fibres as a climbing framework, and a second phase, in the joint cavity, characterized by PMNG metabolic activation, endocytosis of ICs, and degranulation. The apparent inability of PMNGs in the synovial membrane to ingest ICs and become degranulated might be due to not only concentration differences of ICs and leukotactic factors between the joint cavity and the synovial tissue but also might be related to the apparently active interaction with collagen.
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PMID:Leukocyte migration in synovial tissue. Leukocyte distribution, orientation, and migratory pattern after immune complex deposition in rabbit knee joints. 275 15

Serum proteins have never been described in enamel as they have been in dentin or bone where they are bound to apatite, may be because of the specific organic/crystal relationship which makes enamel crystals different from the other biological apatites. In the present study, crystals from bovine developing enamel have been isolated to test their ability to bind serum albumin in vitro. Those crystals, although naturally coated with enamelins proved to be able to bind gold-labelled serum albumin. Consequently, free binding sites exist at the surface of these biological crystals. It is suggested that the 'sheath' surrounding crystals in TEM observations is the fixed aspect of a dynamic process in vivo. Finally, the lack of blood proteins in enamel cannot be attributed to a particular property of enamel crystallites.
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PMID:In vitro albumin binding on apatite crystals from developing enamel. 350 96

To resolve discrepancies between its enzymological activity and its in vitro or in vivo activity, 6-acetylmethylenepenicillanic acid (Ro 15-1903), a potent beta-lactamase inhibitor, was investigated for its chemical stability and its ability to penetrate the bacterial cell envelope. Although Ro 15-1903 was fairly stable in water or saline, it was found to be unstable in a rich medium, in mouse plasma and in human serum. Decomposition half-lives in Tryptic Soy Broth (TSB) and mouse plasma were determined by spectrometry to be 1.3 hours and 12 minutes respectively. These values were confirmed by a biochemical method for determination of Ro 15-1903. Furthermore, a large enhancement of the in vitro activity was noticed when the assay medium was changed from TSB to a synthetic medium in which Ro 15-1903 was more stable. The ampicillin-potentiating activity marginally increased if a permeability mutant harboring the R6K plasmid, which codes for TEM-1 beta-lactamase production, was used instead of the wild-type strain. These results prove that the chemical instability of Ro 15-1903 is the main cause of its disproportionally low activity in vitro and in vivo. Ro 15-1903 is not nonspecifically inactivated by proteins, since it did not lose its activity after incubation with bovine serum albumin (50 mg/ml) for 2 hours at 37 degrees C. It seems to react specifically with beta-lactamase.
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PMID:Studies on 6-acetylmethylenepenicillanic acid (Ro 15-1903). III. Relationship between in vitro activity and chemical stability. 631 68

Female CBA/H-T6T6 mice were given daily i.p. injections of 1 ml of saline containing 250 mg of human serum albumin (HSA) for 7 consecutive days. Control mice received the same volume of saline only. At approximately 24 hourly intervals for the 10 days after the first injection, groups of mice (3 HSA and 1 saline-injected) were killed and kidney tissue was taken for light (LM) scanning (SEM) and transmission (TEM) electron microscopy. Small numbers of glomeruli with Bowman's space filled with protein and fine, radially-disposed casts in collecting tubules were observed by LM. SEM revealed focal changes in both endothelium and epithelium, and in a few cases severely damaged epithelial cells were seen. TEM showed numerous small regions of loss or change in shape of foot processes. Epithelial cell branches became increasingly swollen. By the third day after the last injection glomerular morphology appeared to have returned to normal. Although the cause of the proteinuria was attributed to the effects of HSA-induced increased blood viscosity, the focal distribution of the observed morphological changes remains unexplained.
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PMID:Morphological changes in the kidneys of mice with proteinuria induced by albumin-overload. 661 9

The aim of the present work is to prepare and characterize a functionalized latex with chloromethyl groups on the surface and to perform the covalent coupling of anti-human serum albumin (a-HSA) IgG protein. The chloromethyl-styrene latex (CMS) was synthesized by means of a core-shell emulsion polymerization in a batch reactor. The monodisperse-obtained latex was characterized by determining the diameter (TEM and PCS), the surface charge density (conductometric and potentiometric titration), the amount of chloromethyl groups on the surface (hydrolysis reaction), and the stability vs electrolyte concentration (turbidity measurements). Electrokinetic characterization was also performed (electrophoretic mobility versus pH and ionic strength). IgG was chemically bound to the latex particles under different sensitization and block-stabilization conditions. Colloidal stability of complexes was studied to select an immunolatex suitable for the development of latex immunoassays. The final part of this work consists of a study of the immunoreactivity of the IgG-latex complexes at different pH and ionic strength, in particular under physiological conditions. The results show that chemically bound IgG to chloromethyl latex provides an IgG-latex complex suitable for application in immunodiagnosis tests.
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PMID:Chloroactivated latex particles for covalent coupling of antibodies. Application to immunoassays. 929 2

Human transferrin was covalently coupled to ultrasmall superparamagnetic iron oxide (USPIO) particles, and the transferrin-USPIO obtained was investigated in vivo in experimental SMT/2A tumor-bearing rats (rat mammary carcinoma). Physicochemical characterization showed an overall size of 36 nm (DLS) with a core size of 5 nm (TEM). Relaxivities were R1 = 23.6 and R2 = 52.1 liter/mmol.s (0.47 T). Bound transferrin was 280 micrograms/mg of iron. Pharmacokinetic investigations revealed a half-life of 17 min in normal rats. The MR evaluation of tumor signal intensity over time showed a 40% (range 25-55%) signal reduction 150 min after injection with the reduction persisting for at least 8 h. Control experiments using the parent USPIO compound or USPIO labeled with a nonspecific human serum albumin (HSA-USPIO) showed a change of only 10% (range 5-15%) in tumor signal intensity over time. The results demonstrate that a combination of the USPIO relaxivity properties with the specificity of transferrin-mediated endocytosis allows in vivo detection of tumors by MR imaging.
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PMID:Targeting of ultrasmall superparamagnetic iron oxide (USPIO) particles to tumor cells in vivo by using transferrin receptor pathways. 970 5

The effects of a recombinant mouse amelogenin (rM179) on the growth of apatite crystals nucleated on a bioactive glass (45S5 type Bioglass) surface were investigated with a view to gaining a better understanding of the role of amelogenin protein in tooth enamel formation and of its potential application in the design of novel enamel-like biomaterials. Bioglass discs were incubated in phosphate-buffered saline (PBS) to preform a calcium phosphate surface layer and subsequently immersed in blank, bovine serum albumin (BSA)- and rM179-containing supersaturated calcification solutions (SCS(B), SCS(BSA) and SCSrM179), respectively. Calcium phosphate layers formed on all the treated samples and were characterized to be apatite by X-ray diffraction and Fourier transmission infrared spectrophotometry. Under scanning electron microscopy, plate-shaped crystals (approximately 50 nm thick and 300-600 nm across) were observed on the samples after PBS incubation. The crystals grown from SCS(B) were of the typical plate shape except for an increased thickness, while needle-shaped crystals (200-300 nm long and 50-70 nm thick) were precipitated on the SCS(BSA)-immersed samples. Interestingly, it was found that the crystals deposited on the SCSrM179-immersed samples adopted an elongated, curved shape (approximately 500 nm long and approximately 120 nm thick). Further TEM observations showed that the crystals generated by the SCSrM179 immersion appeared to be composed of bundles of lengthwise crystals (15-20 nm thick) orientated parallel to one another, much alike the long and thin crystals observed in the very early stage of enamel formation. The significant modulation by the rM179 protein of apatite crystal growth is quite different from the overall inhibition observed by BSA and most likely is relevant to the specific function of the amelogenin matrix in controlling enamel crystal growth in vivo.
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PMID:Modulation of apatite crystal growth on Bioglass by recombinant amelogenin. 1050 73

Oppositely charged globular protein and surfactant systems, such as lysozyme-sodium dodecyl sulfate (SDS) and ovalbumin-dodecyltrimethylammonium chloride (DOTAC) form precipitate, gel, and colorless solution in water over a wide concentration range. Bluish solutions are also recognized in connection with the redissolution of precipitate as well as prior to the gel formation. For the lysozyme-SDS system the bluish solution has been suggested to consist of finely dispersed gel particles in solution. The oppositely charged bovine serum albumin (BSA)-DOTAC-water system forms only a large, clear solution phase and a narrow, bluish solution region within a very limited surfactant concentration range. In the lysozyme-SDS system the formation of protein-surfactant aggregates and their growth and breakdown are studied in detail by cryogenic-transmission electron microscopy (cryo-TEM) method. In particular a series of samples with an increased surfactant concentration at fixed 4 wt% of lysozyme is studied. Imaging of the bluish solution at different protein concentrations exhibits large aggregates in the form of rod-like, sheet-like, and star-like objects which are attributed to the gel. At excess amounts of SDS, in the colorless solution, only small objects are detected. In the ovalbumin-DOTAC-water and BSA-DOTAC-water systems large aggregates are also observed in the bluish solutions. Colorless solutions for these two systems show the presence of small objects in the cryo-TEM micrographs. Ultrathin sections of the lysozyme and ovalbumin gels fixed with OsO(4) also show the presence of aggregated structures as judged from the transmission electron microscopy observations. Copyright 2000 Academic Press.
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PMID:A Cryo-TEM Study of Protein-Surfactant Gels and Solutions. 1066 12

Chitosan nanoparticles (CS NP) with various formations were produced based on ionic gelation process of tripolyphosphate (TPP) and chitosan. They were examined with diameter 20-200 nm and spherical shape using TEM. FTIR confirmed tripolyphosphoric groups of TPP linked with ammonium groups of chitosan in the nanoparticles. Factors affecting delivery properties of bovine serum albumin (BSA) as model protein have been tested, they included molecular weight (Mw) and deacetylation degree (DD) of chitosan, the concentration of chitosan and initial BSA, and the presence of polyethylene glycol (PEG) in encapsulation medium. Increasing Mws of chitosan from 10 to 210 kDa, BSA encapsulation efficiency was enhanced about two times, BSA total release in PBS (phosphate buffer saline) pH 7.4 in 8 days was reduced from 73.9 to 17.6%. Increasing DD from 75.5 to 92% promoted slightly the encapsulation efficiency and decelerated the release rate. The encapsulation efficiency was highly decreased by increase of initial BSA and chitosan concentration; higher loading capacity of BSA speeded the BSA release from the nanoparticles. Adding PEG hindered the BSA encapsulation and accelerated the release rate.
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PMID:Effect of molecular structure of chitosan on protein delivery properties of chitosan nanoparticles. 1248 Feb 87


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