Diamond-like carbon films for polyethylene femoral parts: Raman and FT-IR spectroscopy before and after incubation in simulated body liquid.

In artificial prosthetics for knee, hip, finger or shoulder joints, ultrahigh molecular weight polyethylene (UHMW-PE) is a significant material. Several attempts to reduce the wear rate of UHMW-PE, i.e. the application of suitable coatings, are in progress. A surface modification of polyethylene with wear-resistant hydrogenated diamond-like carbon is favourable, owing to the chemical similarity of polyethylene (-C-H(2)-)(n) and C:H or amorphous C:H (a-C:H) coatings with diamond-like properties. In the present study, the microstructure of a-C:H coatings on UHMW-PE substrates was investigated by Raman and Fourier transform infrared (FT-IR) spectroscopy. FT-IR spectroscopy shows very broad absorption lines, which point to the disorder and diversity of different symmetric, asymmetric aromatic, olefin sp(2)-hybridized or sp(3)-hybridized C-H groups in the amorphous diamond-like carbon coating. Following a long incubation of 12 months in a simulated body liquid, the structural investigations were repeated. Furthermore, fractured cross-sections and the wetting behaviour with polar liquids were examined. After incubation in simulated body liquid, Raman spectroscopy pointed to a reduction of the C-H bonds in the diamond-like carbon coatings. On the basis of these findings, one can conclude that hydrogenated diamond-like carbon is able to interact with salt solutions by substituting the hydrogen with appropriate ions.

[Calcium-oxygen modified amorphous and nanocrystalline carbon layers as biomaterials]. / Kalzium-Sauerstoff-modifizierte amorphe und nanokristalline Kohlenstoffschichten als Biomaterial.

Undoped and Ca-O-modified diamond-like carbon coatings were deposited by a direct current discharge. Hardness and Young's modulus of Ca-O-modified DLCs were reduced in comparison with the undoped DLC, but the adherence of the Ca-O-modified films is improved. Ca-O-modified DLCs have a higher fraction of nano-crystalline regions with carbon in sp2 hybridisation. In addition, an increased oxygen content and CaCO3 was identified in Ca-O-modified DLCs. While mouse fibroblasts of the type L929 attach and grow on unmodified diamond-like carbon coatings synthesized by the decomposition of hydrocarbon, the addition of CaO-H2O into the precursor gas improves the coatings biological acceptance by the cells.

Nano- and microstructure of short fibre reinforced and unreinforced hydroxyaptite.

Hydroxyapatite (HA) and alumina short fibre reinforced hydroxyapatite (Al2O3/HA) were processed by uniaxial pressing of green bodies with 200 MPa and sintering in air for 4 hours at 1150 degrees C, 1175 degrees C and 1200 degrees C. The phase composition of the materials were investigated by transmission electron microscopy and Raman spectroscopy. Results were supported by X-ray diffraction. Amorphous calcium phosphate could be found either as islands in unreinforced HA or at the grain boundaries in the Al2O3/HA composite. The reinforced calcium phosphate contains an enhanced amount of decomposition products like tetracalcium phosphate.

Diamond-like carbon coatings with Ca-O-incorporation for improved biological acceptance.

Diamond-like carbon (DLC) coatings were modified by doping the thin films with Ca-O compounds. Raman spectroscopy indicates growth of sp(2)-hybridised, ordered regions in size and/or number within the amorphous carbon-hydrogen network as a result of the Ca-O-incorporation. CaCO(3) was identified by X-ray induced photoelectron spectroscopy. Proliferation and morphology of L929 mouse fibroblasts reveal improved biocompatibility of Ca-O-modified DLC.

Expression of the messenger RNAs for luteinizing hormone-releasing hormone (LHRH) and its receptor in human ovarian epithelial carcinoma.

Recently we reported the presence of specific high affinity binding sites for luteinizing hormone-releasing hormone (LHRH) and its analogues (Kd = 1.5 or 1.7 nM) in the human epithelial ovarian cancer cell lines EFO-21 and EFO-27. The proliferation of these cell lines was inhibited by nM concentrations of a LHRH agonist. This study was performed to ascertain whether these ovarian cancer cell lines produce LHRH and whether the high affinity LHRH binding site found previously was identical to the pituitary LHRH receptor. Significant amounts of immunoreactive LHRH were found in the extracts of both the EFO-21 cell line (449 +/- 56 fmol/10(6) cells) and the EFO-27 line (409 +/- 76 fmol/10(6) cells). LHRH bioactivity of these extracts, assessed in terms of release of luteinizing hormone by rat pituitary cells, was comparable to that of authentic LHRH. EFO-21 and EFO-27 cells expressed the mRNAs for both human LHRH and human LHRH receptor as assessed by reverse transcriptase-PCR using oligonucleotide primers according to published sequences. In addition, in eight of eight biopsy samples of human epithelial ovarian cancers we detected mRNA for LHRH, six of these specimens expressed the mRNA representing the LHRH receptor. These data support the concept that human epithelial ovarian cancers might have a local system based on LHRH to regulate cell proliferation. It is still obscure at present whether LHRH produced locally has a stimulatory, inhibitory, or no impact on the proliferation of ovarian cancer cells. However, exogenous LHRH agonists seem to have clear antiproliferative activity, probably mediated through LHRH receptors. This finding might provide the base for novel approaches in the therapy of epithelial ovarian cancer.

Expression of luteinizing hormone releasing hormone and its mRNA in human endometrial cancer cell lines.

Recent results have shown that specific binding sites for luteinizing hormone-releasing hormone (LHRH) are present in biopsy samples of human endometrial cancer and in the human endometrial cancer cell lines Ishikawa and HEC-1A. The proliferation of these cell lines was retarded by LHRH analogs. The present study was undertaken to determine whether these endometrial tumor cells also produce LHRH or an LHRH-like peptide which could serve as natural ligand for the LHRH binding sites. Using a specific antibody, LHRH-immunoreactivity was detected in extracts of Ishikawa (426 +/- 84 fmol/10(6) cells) and HEC-1A (368 +/- 41 fmol/10(6) cells) cells. LHRH-like bioactivity of these samples was assessed in a rat pituitary cell culture system. The release of luteinizing hormone induced by endometrial cancer cell extracts corresponded to that obtained with comparable amounts of authentic LHRH. The expression of the mRNA for LHRH could be demonstrated by reverse transcriptase - polymerase chain reaction using specific primers according to the published sequence and by subsequent Southern blot analysis. The presence of immuno- and bioactive LHRH-like factors and the demonstration of expression of the mRNA for LHRH in two human endometrial cancer cell lines supports the concept of an autocrine regulatory system based on LHRH in endometrial cancer.

Chromatographic and antigenic properties of Echinococcus granulosus hydatid cyst-derived glycolipids.

The neutral and acidic fraction glycolipids of Echinococcus granulosus metacestode tissue compartments were isolated, defined by their chromatographic and antigenic properties, and assessed as to their efficacy as antigens in the serodiagnosis of human hepatic cystic and alveolar echinococcosis, and other helminthiases. Analyses were accomplished by thin-layer chromatography immunostaining and ELISA. The neutral glycolipid fraction's major carbohydrate epitope was the same as or very similar to that of Taenia crassiceps neutral glyco(sphingo)lipids, as represented by the 'neogala'-series core structure. The blood group-active, carbohydrate epitope P1 was expressed by a number of neutral fraction glycolipid component bands. The reverse-phase, thin-layer chromatography-isolated neutral fraction glycolipid component, designated Ag1, was efficient in the serological discrimination of cystic echinococcosis medium to high-titred sera. Ag1 did not specifically discriminate low-titred sera, i.e., other human helminthiases. The detected sialic acid residues of the acidic fraction glycolipids, on enzymatic cleavage, were identified as N-acylneuraminic acid and terminal. The acidic fraction glycolipids exhibited the paradox of only chemically minor components being antigenic towards cystic and alveolar echinococcosis infection sera. The combined acidic fraction glycolipid components Ra and Rx were capable of serological discrimination between cystic echinococcosis, alveolar echinococcosis and other helminthiases.

High affinity binding and direct antiproliferative effects of LHRH analogues in human ovarian cancer cell lines.

Recently, specific binding sites for luteinizing hormone releasing hormone (LHRH) and its analogues have been demonstrated in biopsy samples of human epithelial ovarian cancer. Their biological significance remained obscure. In this study we ascertained whether such LHRH-binding sites are also present in the human epithelial ovarian cancer cell lines EFO-21 and EFO-27 and if they could mediate antiproliferative effects of LHRH analogues. Using [125I, D-Trp6]LHRH, a high affinity/low capacity binding site was detected in both lines: EFO-21 (Kd1 = 1.5 x 10(-9) M; binding capacity (Bmax1) = 4.9 fmol/10(6) cells) and EFO-27 (Kd1 = 1.7 x 10(-9) M; Bmax1 = 3 fmol/10(6) cells). In addition, a second class of low affinity/high capacity binding sites (EFO-21: Kd2 = 7.5 x 10(-6) M; Bmax2 = 24 pmol/10(6) cells; EFO-27: Kd2 = 4.3 x 10(-6) M; Bmax2 = 14.5 pmol/10(6) cells) was demonstrated. Specific binding of [125I, D-Trp6]LHRH was displaced with nearly equal efficiency by unlabeled [D-Trp6]LHRH, the LHRH-antagonists SB-75 and Hoe-013, and by native LHRH but not by unrelated peptides such as oxytocin and somatostatin. In the presence of 10(-5) M agonist [D-Trp6]LHRH, the proliferation of both cell lines was significantly reduced to 77% of controls after 24 h and to approx. 60% after 6 days. Lower concentrations (10(-9) M) of the agonist, significantly decreased the proliferation to 87.5% for EFO-21 and 86% for EFO-27 after 6 days. These antiproliferative effects were enhanced by increasing doses of [D-Trp6]LHRH and were maximal at 10(-5) M (EFO-21: 65.5% of control, EFO-27: 68% of control). Similar dose-dependent antiproliferative effects were obtained in EFO-21 line with the LHRH-antagonists SB-75 and Hoe-013, while these analogues had no effects on the proliferation of EFO-27 cells. SB-75 partly antagonized the antiproliferative effect of [D-Trp6]LHRH in a dose dependent way in the EFO-27 line. These data suggest that LHRH analogues can directly inhibit the in vitro proliferation of human ovarian cancer cells. This effect might be mediated through the high affinity LHRH binding sites.