Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydrogels prepared by radiation-induced polymerization at a low temperature have been used as carriers for the controlled release of peptides and proteins. It was found that polymerization of 2-hydroxyethyl methacrylate in the presence of poly (ethylene glycol) methyl ether (MPEG) enabled the more porous and swellable matrics to be obtained, the higher the molecular weight of MPEG. As a consequence, protein release took place at an increasing extent and, provided that MPEG molecular weight was high enough, high molecular weight proteins could also be released. Such a state of affairs was not met in the case of hydrogels based on poly (2-hydroxyethyl acrylate). SEM analysis revealed that even high molecular weight MPEG did not give rise to any porosity, even though the degree of swelling was very high. As a result, no protein release was observed. It was therefore concluded that control of hydrogel porosity for the controlled release of large proteins is of overwhelming importance.
 ...
PMID:Controlled release of proteins and peptides from hydrogels synthesized by gamma ray-induced polymerization. 150 92

The spontaneous reaction of 110 microM chlorambucil (4-[p-[bis(2-chloroethyl)amino]phenyl]-butanoic acid; CHB) with 5 mM GSH at 37 degrees C in physiological phosphate-buffered saline for 35 min gave primarily the monoglutathionyl derivative, 4-[p-[N-2-chloroethyl,N-2-S-glutathionylethyl]amino]phenyl]-butano ic acid; CHBSG) and the diglutathionyl derivative, 4-[p-[bis(2-S-glutathionylethyl]amino]phenyl]-butanoic acid (CHBSG2) with small amounts of the hydroxy-derivatives: 4-[p-[N-2-chloroethyl,N-2-hydroxy-ethyl]amino] phenyl-butanoic acid (CHBOH) and 4-[p-[N-2-S-glutathionylethyl-2-hydroxyethyl]amino]phenyl]-butanoi c acid (CHBSGOH). The inclusion of approximately physiological amounts of human glutathione S-transferases (GSTs) A1-1, A2-2, P1-1, M1a-1a M3-3 or P1-1 (for nomenclature see Mannervik et al., 1992, Biochem. J., 282, 305) had little or no catalytic effect on these reactions as determined by loss of CHB. However, GTSs A1-1 and A2-2 were associated with a significant increase of CHBSG at the expense of CHBSG2 + CHBSGOH suggesting that these GTs sequestered CHBSG at the active site. This interpretation was supported by inhibition studies which showed that CHBSG was a pure competitive inhibitor of the activity of GSTs A1-1 and A2-2 towards 1-chloro-2,4-dinitrobenzene with Ki's of 1.3 and 1.2 microM respectively. GSH transferases P1-1 and M1a-1a were inhibited by CHBSG above 10 microM. Incubation of 2 microM CHB, a concentration which may be of more significance for chemotherapy, in the presence or absence of GST A1-2 (20-50 microM) showed catalysis of GSH monoconjugation equivalent to 18% of the spontaneous rate. However, the dominant effect again was the sequestration of CHBSG which reached 74.3 +/- 1.5 (SEM)% of the total reactants at 60 min compared to 28.9 +/- 0.3(SEM)% in controls. CHBSG, although possessing a potential electrophilic centre, showed no detectable alkylation of plasmid DNA but indirect evidence was obtained that it alkylated other cellular macromolecules. It is concluded that the contribution of GSTs to catalysis of CHB detoxication will depend on factors not previously considered, namely the relative molarities of CHB, CHBSG and GSTs, and the cellular capacity to excrete CHBSG to relieve product inhibition.
 ...
PMID:Chlorambucil-monoglutathionyl conjugate is sequestered by human alpha class glutathione S-transferases. 152 May 81

The adsorption of 2-hydroxyethyl methacrylate (HEMA) on bovine dentin from aqueous solution was examined to clarify the priming effects of HEMA on dentin bonding. HEMA adsorption was characterized by: (1) slow attainment of equilibrium at higher concentrations (after 72 h); (2) a linear isotherm with a maximum possible adsorption, where an abrupt horizontal plateau occurred; (3) the large adsorption of ca. 2.5% by weight at the plateau; and (4) a vertical initial slope of the isotherm. The morphological difference between dentin powder surfaces before and after adsorption could not be determined. After heating, however, dentin powder which adsorbed HEMA was more resistant to demineralization with 6N HCl than the powder which did not adsorb. SEM examinations demonstrated that there was a demineralization-resistant dentin layer in tooth which adsorbed HEMA. The results indicated that HEMA infiltrated into intertubular dentin during adsorption.
 ...
PMID:Adsorption of 2-hydroxyethyl methacrylate on dentin from aqueous solution. 209 9

Glucose oxidase (GOD) was immobilized in a poly(2-hydroxyethyl methacrylate) (HEMA) membrane through matrix entrapment in order to investigate the effect of various parameters (e.g. concentration of ingredients, temperature, repeated interaction with glucose and shelf storage) on the activity of the enzyme. Permeability of the membrane to a model permeant was tested and SEMs were obtained. It was observed that upon immobilization the affinity of GOD towards glucose was substantially decreased, and increasing the GOD content of the membrane adversely affected the activity. Membranes with the highest enzyme activity were also found to be the most permeable. Changes were detected in the pH and temperature where GOD is most active. Membrane permeability was observed to increase when crosslinker, and/or HEMA concentrations were low. The same parameters were also found to alter the morphology of the membrane as observed under SEM.
 ...
PMID:Immobilization of glucose oxidase in poly(2-hydroxyethyl methacrylate) membranes. 342 49

In this paper a technique is described, using Araldite CY 223 and hardener HY 2967 as injection material, for preparing corrosion casts or histological sections. The plastic has a viscosity (at 39-40 degrees C) similar to that of blood, a gelling time of approximately 17 min (at 40 degrees C), and an exothermic transition energy of delta H = 80.28 +/- 3.20 cal/gm. The influence of the plastic on the tissue is discussed. The histological sectioning of fixed tissue containing Araldite-filled blood vessels after embedding in 2-hydroxyethyl-methacrylate (GMA) is described. When using GMA in a modification of the mixtures of Ruddell (1967) and Sims (1974), methylbenzoate is recommended as an intermedium in order to obtain a more uniform infiltration and reproducible section thickness. At the same time methylbenzoate is recommended as a storing fluid. Sections of 2-3 micrometers afford satisfying morphologic and morphometric results. This method allows various arterial wall dimensions to be measured easily, and provides a suitable means to compare histometric values with SEM data derived from corrosion casts.
 ...
PMID:A new plastic for morphometric investigation of blood vessels, especially in large organs such as the human liver. 711 2

Poly(2-hydroxyethyl methacrylate) (pHEMA) membrane was prepared via photopolymerization and activated with epichlorohydrin. The conidia of Aspergillus niger strains (wild type 'NRRL-3' and genetically improved strain 'NRRL-3/2-2A') were covalently-immobilized on the membranes. Uniform growth of A. niger cells on membrane surfaces was verified by SEM. The glucose oxidase (GOD) activity of the immobilized cells was determined in a continuous flow membrane reactor (CFMR) by assaying for hydrogen peroxide produced. The activity was also determined in the culture fluids of A. niger strains, freely grown in batch cultures. The CFMR was run with 0.1 mol dm-3 glucose with a fixed flow rate of 20 cm3 h-1 for 60 h during which a 10% loss of the original activity was detected. The loss of the activity with the freely cultivated mycelia was about 50% after 30 h. The GOD activity of the improved strain NRRL-3/2-2A was about 20 times higher whether in immobilized or in free form. The GOD activity of the immobilized A. niger strains in the continuous flow membrane reactor was found to be 2.5 times better than their counterparts freely grown in batch cultures indicating that immobilization increases the activity and the stability of the microorganisms.
 ...
PMID:Covalent immobilization of Aspergillus niger on pHEMA membrane: application to continuous flow reactors. 776 11

A poly(2-hydroxyethyl methacrylate) (pHEMA)-grafted polymer film was prepared by plasma-induced graft copolymerization onto an elastic material, silicone rubber, and a plastic material, poly(4-methyl-1-pentene) (TPX). The control, Ar plasma-treated and pHEMA-grafted silicone rubber and TPX surfaces were characterized by ESCA, FTIR-ATR, SEM and contact angle techniques. ESCA verified the respective chemical shift of control and Ar plasma-treated films. The presence of the grafted pHEMA was also verified by ESCA. The introduction of pHEMA onto a hydrophobic support provided an adequate surface for rabbit corneal epithelium cell attachment and growth. Cell attachment and growth onto these surfaces were examined by light microscopy. Cell attachment onto the control and Ar plasma-treated surfaces was negligible, while improved attachment and growth of rabbit corneal epithelium cells was demonstrated on the pHEMA-grafted polymeric surface. At 72 h, the pHEMA-grafted silicone rubber surface attached and grew more cells as compared with those on a pHEMA-grafted TPX surface. The pHEMA-grafted silicone rubber surface demonstrated a confluent cell layer after 72 h.
 ...
PMID:Plasma-induced graft copolymerization of HEMA onto silicone rubber and TPX film improving rabbit corneal epithelial cell attachment and growth. 819 88

It has been reported that the presence of a smear layer on dentinal substrates can compromise bonding. Typically, smear layers are removed by acidic agents that selectively extract calcium salts from dentin surfaces to leave a collagen-rich substrate. Acid-conditioned dentin (i.e., demineralized) is then primed and an adhesive agent applied. In the present study, we removed smear layers by "polishing" dentin specimens with a hydroxyapatite paste and ultrasonication. Bonding procedures were carried out by means of an aqueous solution of 20% 2-methacryloyloxyethyl phenyl phosphoric acid (phenyl-P) and 30% 2-hydroxyethyl methacrylate, referred to as 2OP-30H, a "self-etching primer". The 20P-30H solution was applied to "intact" dentin (i.e., non-demineralized) for either 30 or 60 s. Control samples received no application (O s) of the self-etching primer. Mean tensile bond strengths (10 MPa) were similar in both the 30-second- and 60-second-primed groups. The widths of formed hybrid layers varied from 0.3 +/- 0.2 micron at O s application (control) to 2.1 +/- 0.3 micron for the 30-second group and 4.1 +/- 0.2 micron for the 60-second group. SEM and TEM observations revealed that the 20P-30H self-etching primer created diffusion channels into "intact" calcium-rich dentin which permitted monomer to infiltrate dentin substrates. Hybrid layers identified under microscopic examination demonstrated resistance to both HCI and NaOCI treatments, suggesting that the hybrid layer was not defective, and that bonding was stable.
 ...
PMID:Bonding to intact dentin. 895 25

An investigation of the surface by XPS photoelectron spectroscopy has shown that the process of production of cast contact lenses based on poly(2-hydroxyethyl methacrylate-co-diethyleneglycol methacrylate) is accompanied by mass transfer at the lens-mold boundary. This phenomenon, which impairs the compatibility of the lens during its application, can be considerably suppressed by employing a suitable surface modification of polypropylene molds. The surface treatment consisting in the oxidation of the mold surface by an AC corona discharge in the oxygen atmosphere increases hydrophilicity of the material, thus facilitating separation of the lens from the mold. The results of the XPS study were also confirmed microscopically by employing the SEM method.
 ...
PMID:The surface treatment of polypropylene molds and its effect on the quality of cast contact lenses. 1014 96

Aerosolized hypertonic saline is currently being investigated as a new agent for the treatment of impaired mucociliary clearance which occurs in many respiratory diseases. Mannitol aerosols, in particular dry powder inhalers, have been proposed as an alternative treatment to saline, offering the same osmotic load with other benefits. However, the effects of these hypertonic aerosols on airway epithelial ion transport processes have not been tested in human subjects in vivo. This report examines the effect of these solutions on airway ion transport using the nasal potential difference (PD) technique. Seven healthy nonsmoking adult volunteers were studied. On different days, a dose-response curve was constructed for the saline added to Krebs N-[2-hydroxyethyl] piperazine-N'-[2-ethanesulphonic acid] (HEPES) diluent. The reversibility of this saline effect was measured, and the response to additional saline (500 mM) and mannitol (1 M) compared. Hypertonic saline decreased nasal PD in a dose-related manner, with mean (SEM) decreases in PD (less negative) of 6.6 (1.5), 7.6 (1.6), 10.0 (2.0), 13.1 (2.9) and 14.8 (3.2) mV (n =4) for addition of 150 mM, 250 mM, 500 mM, 1,200 mM and 2,000 mM NaCl to the Krebs HEPES diluent, respectively. The effect of hypertonic saline was fully reversible with washout for 3 min (presaline 15.9 (0.5) mV, postwashout 15.8 (1.1) mV, (n=4)). The hypertonic saline response was rapid in onset, sustained for at least 4 min, and decreased PD from 13.7 (1.7) mV to 5.1 (1.3) mV (n = 7, p < 0.001). In contrast, addition of mannitol to the perfusate did not significantly alter nasal PD, with a nonsignificant trend towards an increase (more negative) in the PD, (premannitol 13.9 (1.6) mV, postmannitol 15.3 (2.0) mV, n=7). As the osmotic stimulus of the 1 M mannitol is similar to that of the 500 mM sodium chloride, the divergent nasal potential difference responses suggest that the response to the saline was specific to the sodium chloride itself and not the simultaneous change in osmolarity. This demonstrates that the human airway epithelium in vivo can respond to topical hypertonic saline independent of the altered osmolarity.
 ...
PMID:Hypertonic saline alters ion transport across the human airway epithelium. 1133 19


1 2 3 4 5 6 7 8 9 Next >>