HemA protein

Figure 6 Permeation profiles of proteins through HEMA-AEMA copolymer membrane at 30°. The arrows represent the UV irradiation to the membrane. (O) Insulin ( ) lysozyme (A) chymotrypsin (A) albumin. (From Ref. 28.)...

Cytokines are proteins that serve as signal molecules in cell-cell communication, and as such, perform a central and very diverse function in growth and differentiation of an organism. Representatives of cytokines control proliferation, differentiation and function of cells of the immune system and of cells of the blood-forming system. Furthermore, they are involved in processes of inflammation and in the neuronal, hema-poetic and embryonal development of the organism. Known cytokines include the interleukins (IL), erythropoietin, growth hormone, interferons (INF) and tumor necrosis factor (TNF) (see Table 8.1). A review of cytokines and cytokine receptors is to be found in HiU and Treisman, (1995) Taniguchi et al., (1995) and Moutoussamy et al., (1998). 

On hydrophilic surfaces, such as PVA or poly(HEMA), OH-groups of the materials are incorporated in the network structure of adsorbed water molecules (see Sect. 4.4). In consequence, the absolute value of Wj(3 — Wi1 is considered to become still smaller, where - owing to the stabilization of water molecules on the hydrophilic surface - the water-removing-process (reverse reaction of Eq. (2.6)) proceeds slowly. Many experiments were carried out with water-adsorbed hydrophilic surfaces, the behavior of which was time-dependent. In a similar way, the water removal from the proteins [Eq. (2.9)] is also considered to proceed slowly. Thus, we must be careful in considering experimental results in comparison with the data in Tables 3, 4 and 5. 

In this connection, it is to be noted that polyamine-modified po y(HEMA) surfaces exhibit surprisingly reduced interaction with blood proteins and cells (e.g. erythrocyte, platelet, lymphocyte etc.), as will be discussed in Sects. 4.3 and 4.4. The present author considers that there are probably closely related mechanisms between the suppressing effect of the poly(DIPAM) or (Methacrol)-modi-fied SPU and that of the polyamine-modified poly(HEMA) surfaces, with regard to their mode of interaction with the biological elements. 

Hydrophilicity and hydrophobicity are the most fundamental properties to be controlled for materials whenever they are utilized in biomedical devices. Protein-adsorption behavior on several biomaterials of different hydrophilicity was discussed by comparing available data with two modellings (Ikada and Peppas) for the protein-adsorption process. The adsorptive behavior of poly(HEMA) carrying polyamine functional groups was also discussed. It is well-known that protein adsorption is the first event when any of the body fluids encounters an artificial material. 

An A-B-A-type block copolymer (HEMA-St-HEMA) was shown to form a microdomain structure and to exhibit excellent blood compatibility in both in vitro and ex vivo examinations. For instance, the luminal surface of the HEMA-STY coated vascular graft was bare without detectable thrombi after 372-day implantation in dog carotid aortas. The excellent blood compatibility was discussed by taking results of the unique mode of protein adsorption of HEMA-STY surface into account. 

The Effect of Monomer Purity on Protein Adsorption onto Poly-(HEMA). The importance of relatively minor contamination of the monomers used in formulating hydrogels to be used in biomedical applications has not been recognized widely as yet, although Bruck has referred to this problem in connection with the soft contact lens (26). Protein adsorption studies performed with hydrogels made with monomers of typical commercial quality illustrate this potential problem. 

Fortunately, highly purified HEMA became available (from Hydro Med Sciences) about this time, and other monomers were readily purified by vacuum distillation. The poly (HEMA) hydrogels made with the purified HEMA showed far lower protein adsorption from either water or buffered saline than hydrogels made with the commercially available HEMA as experiment C, Table I shows. These results emphasize the biological importance of hydrogel composition in particular and biomaterial composition and purity in general. 

Figure 1. The effect of MAAc on protein adsorption onto poly(HEMA)/ Silastic at low ionic strength. The solvent was 0.005M HEPES, pH 7.4. Protein concentration was 0.5 mg/ml. See Table II for other details.

Table II. Effect of MAAc on Protein Adsorption onto Poly (HEMA) /Silastic Hydrogels ...

The listed amount of methacrylic acid was contained in the HEM A monomer used to form the poly (HEM A)/Silastic hydrogels, which had 20% grafted poly(HEMA). These hydrogels were equilibrated for 45 hrs at 37°C in 0.5mg/ml protein solutions in the listed solvents and then rinsed in the equilibration solvent, using decantation and dilution and 15 min of stirring. Ninhydrin assays were then used to determine absorbed protein. 

The poly (HEM A) sheets were prepared by B. Ratner using a special technique he developed. The HEMA solutions were poured between glass plates, and polymerization was chemically initiated. The chemical and physical properties of this material are very similar to those of radiation-grafted poly (HEMA) insofar as protein adsorption is concerned. Heterogeneous or homogeneous poly (HEMA) films were made by polymerization in solvents in which the poly (HEMA) is insoluble or soluble, respectively the result is a white opaque material in the first case and a transparent material in the second case. The resulting films were washed free of excess monomer and then soaked in the buffer to be used in the fibrinogen adsorption experiment for 10 days at 37 °C prior to the actual experiment. 

The poly (HEMA) films used in this study were much thicker (0.1 cm) than those of grafted poly (HEMA) (about 0.001 cm). Assuming equivalent porosities with respect to proteins for both cast and grafted... 

The reduced adsorption of fibrinogen from plasma onto Silastic and poly (HEMA)/Silastic compared with that from pure buffered saline solutions could be caused by competition from other proteins for the adsorption sites. Albumin and y-globulin are both present in plasma in relatively high concentrations (about 45 and 10 mg/ml, respectively, compared with ca. 3 mg/ml for fibrinogen), so either might compete effectively with fibrinogen for adsorption. To test this, mixtures of I-fibrinogen... 

A change in the hydrophilic nature of the polymer surface on irradiation of poly-(p-phenylazoacrylanilide) (PAAn) or its copolymer with HEMA may be used to control the adsorption — desorption behavior of proteins or organic substances onto the polymer [49]. Adsorption of lysozyme onto the copolymer of p-phenylazo-acrylanilide and HEMA was foimd to decrease from 4.6 eg to 1.8 eg per gram of adsorbent on ultraviolet irradiation, which induces the isomerization from the trans to the cis form. The decrease in adsorption ability upon ultraviolet irradiation is explained by a reduction of the hydrophobic interaction between the protein and the polymer, which results from the appearance of hydrophilic cw-form azobenzene on the surface. 

Reagents reactive solely toward the methionyl side-chain in native proteins have not been described to date. Selective conversion of the thioether to the sulfoxide derivative by photosensitized oxidation has been reported in a protein devoid of free thiol groups. The selective photosensitized oxidation employed methylene blue or hema-toporphyrin as sensitizers, and aqueous acetic acid (30-90% v/v), or acidic buffers at pH 2-6.5, as solvents (Scoffone et al. 1970). Anaerobic photo-oxidation in 4 M aqueous acetone has been reported to lead to the same result (Gennari and Jori 1970). Methionine can be regenerated from the sulfoxide by incubation with thiols (5 % aqueous j9-mercapto-ethanol at pH 8.0, for 24 hr under Nj Jori et al. 1968). 

Leakage of various plasma proteins into the urinary space as a result of tubulointerstitial damage caused by conditions such as inflammation may also occur. This can cause hema-... 

Treatment of -ABSC-HEMA with glutaraldehyde produced enzyme supports capable of binding up to 55 wt % trypsin. Incorporation of hydrophobic styrene units Into the support reduced the capacity to 2-. 4 wt X but enhanced the specific activity of the trypsin. The esterase activity of bound trypsin, assayed with TAME, was found to range from 11% to 45% of that exhibited by the free trypsin. Active-site titration of a PHEMA-trypsln conjugate with p-nltrophenyl-p -guanadlnobenzoate HCl Indicated the active species to be 31% of the total amount of protein bound. 

Kleinmann, I., Plicka, J., Smidl, P. and Vins, I. 1994. Hydrophobic interaction chromatography of proteins on HEMA-based sorbents. Am. Lab. April, 34H-34L. 

As stated earlier in this discussion, most non-hema-topoietic malignancies of the mediastinum should be presumed metastatic until proven otherwise. Immunohistologic analysis is only variably productive in establishing a site of origin for secondary carcinomas in this location. If determinants are found that are unassociated with PTCs, such as TTF-1, thyroglobulin, prostate-specific antigen, S-100 protein, FLAP, CA 19-9 (an enteric carcinoma marker), or CA 125 (a serosal and Mullerian tract marker),it is likely that the lesion is a metastasis. Conversely, the presence of coexpression of keratin 5/6, p63, and CD5 would, at least tentatively, appear to support a thymic origin for such a neoplasm. 

Ayan I, Dogan O, Kebudi R, et al. Immunohistochemical detection of p53 protein in rhabdomyosarcoma association with clinicopathological features and outcome. J Pediatr Hema-tol Oncol. 1997 19 48-53. 

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