Comparison of a polymethylmethacrylate and glass-ionomer bone cement using a hemiarthroplasty in the rabbit femur

Polymethylmethacrylate (PMMA) bone cements present various problems with respect to biocompatibility and stability. In order to study the histological changes at the bone-cement interface following total hip replacement, a small animal model was created by implanting hip prostheses using two different bone cements (PMMA and glass-ionomer cement, GIC). Two problems with the use of GIC for fixation of the prosthesis became evident. One year following implantation, histomorphometric analysis of femurs containing the GIC demonstrated significantly higher amounts of osteoid at the bone-cement interface. This disturbance of mineralization is comparable with osteomalacia and probably due to leaching of aluminum ions. In addition the mechanical properties of GIC proved to be inadequate for the loads placed upon it in this hip replacement model.     

Comparative Study of Ultrasonication-Induced and Naturally Self-Assembled Silk Fibroin-Wool Keratin Hydrogel Biomaterials

This study reports the formation of biocompatible hydrogels using protein polymers from natural silk cocoon fibroins and sheep wool keratins. Silk fibroin protein contains β-sheet secondary structures, allowing for the formation of physical cross-linkers in the hydrogels. Comparative studies were performed on two groups of samples. In the first group, ultrasonication was used to induce a quick gelation of a protein aqueous solution, enhancing the ability of Bombyx mori silk fibroin chains to quickly entrap the wool keratin protein molecules homogenously. In the second group, silk/keratin mixtures were left at room temperature for days, resulting in naturally-assembled gelled solutions. It was found that silk/wool blended solutions can form hydrogels at different mixing ratios, with perfectly interconnected gel structure when the wool content was less than 30 weight percent (wt %) for the first group (ultrasonication), and 10 wt % for the second group (natural gel). Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) were used to confirm that the fibroin/keratin hydrogel system was well-blended without phase separation. Fourier transform infrared spectroscopy (FTIR) was used to investigate the secondary structures of blended protein gels. It was found that intermolecular β-sheet contents significantly increase as the system contains more silk for both groups of samples, resulting in stable crystalline cross-linkers in the blended hydrogel structures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the samples’ characteristic morphology on both micro- and nanoscales, which showed that ultrasonic waves can significantly enhance the cross-linker formation and avoid phase separation between silk and keratin molecules in the blended systems. With the ability to form cross-linkages non-chemically, these silk/wool hydrogels may be economically useful for various biomedical applications, thanks to the good biocompatibility of protein molecules and the various characteristics of hydrogel systems.     

Effect of the primary heat treatment on the bond formation in cold welding of aluminum and steel by cold forging

Cold forging enables the manufacturing of high strength monolithic components. When used as joining technology it can also be extended to an enabler of multi-material product design. The contact conditions at the interface between the components during the cold forging process play a crucial role. The joining of two billets of steel and aluminum is investigated by a finite element analysis with regard to the material distribution and the effect of a primary heat treatment of both materials. These parameters affect the surface enlargement and the contact normal stress which are decisive parameters for the formation of a sound bond between aluminum and the hardly cold weldable steel. The experimental results present the effect of a primary heat treatment on the bond formation. Microscopic analyses of the bond formation allow a deeper insight into the bonding mechanism. Thus, the results lead to process design guidelines for cold welding by cold forging.     

Microwave treatment of dietary gelatin does not generate cis-4-hydroxy-l-proline, an inhibitor of collagen biosynthesis

Aqueous solutions (5?g/100?ml) of commercial preparations of (a) an enzymatic partial hydrolysate of gelatin and (b) type A gelatin were subjected to threefold heating to boiling in a domestic microwave oven at 750?W and to conventional heating. Then samples were totally hydrolyzed (6?M hydrochloric acid, 110??°C, 24?h) and investigated for the presence of eight possible stereoisomers of 3- and 4-hydroxyproline (Hyp) using capillary gas chromatography. Amino acids were analyzed as N(O)-trifluoroacetyl 2-propyl esters on Chirasil-l-Val and detected by selected ion monitoring mass spectrometry. Blanks of (a) and (b) were analyzed in parallel. Relative amounts of 5.0±0.2% cis-4-d-Hyp were generated from native trans-4-l-Hyp as a result of total hydrolysis in all samples and independent of previous treatment. Notably, neither cis-3-l-Hyp nor cis-4-l-Hyp could be detected in either of the gelatin samples. Thus a report on the generation of antifibrotic and therefore potentially hazardous cis-3-l-Hyp and cis-4-l-Hyp from protein-bonded native trans-3-l-Hyp and trans-4-l-Hyp on microwave heating of infant formulae could not be confirmed.     

Food reinforcement, the dopamine D? receptor genotype, and energy intake in obese and nonobese humans.

[Correction Notice: An erratum for this article was reported in Vol 122(1) of Behavioral Neuroscience (see record 2008-01943-025). In the original article, the n values (and corresponding percentages) for the number of people with the A1/A1 & A1/A2 and A2/A2 genotypes were reversed in Table 2. The corrected table appears in the erratum, with the revised numbers appearing in bold font.] The authors measured food reinforcement, polymorphisms of the dopamine D? receptor (DRD?) and dopamine transporter (DAT1) genes, and laboratory energy intake in 29 obese and 45 nonobese humans 18-40 years old. Food reinforcement was greater in obese than in nonobese individuals, especially in obese individuals with the TaqI A1 allele. Energy intake was greater for individuals high in food reinforcement and greatest in those high in food reinforcement with the TaqI A1 allele. No effect of the DAT1 genotype was observed. These data show that individual differences in food reinforcement may be important for obesity and that the DRD? genotype may interact with food reinforcement to influence energy intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous hyperaccumulation of nickel, manganese, and calcium in Alyssum leaf trichomes

We have developed commercially viable phytoremediation/phytomining technologies employing Alyssum Ni-hyperaccumulator species to quantitatively extract Ni from soils. The majority of Ni is stored either in Alyssum leaf epidermal cell vacuoles or in the basal portions only of the numerous stellate trichomes. Here, we report simultaneous and region-specific localization of high levels of Ni, Mn, and Ca within Alyssum trichomes as determined by scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX). Plants were grown in high Ni soil, achieving up to 48 400 microg g(-1) Ni in total leaf concentration; however, Ca and Mn were not enriched in the experimental soils. The region-specific localization of hyperaccumulated Ca, Mn, and Ni occurred in three soil types, five Alyssum species/ecotypes, and over a wide range of soil Ni concentrations. The metal concentration in the trichome basal compartment was approximately 15-20% dry weight, the highest ever reported for healthy vascular plant tissue.     

Photocatalytically active thin films on float glass with enhanced hydrophilicity and transmission for photovoltaic applications

In this paper, the results on the preparation of photocatalytically active thin films will be presented. The films based on TiO₂ and were deposited by using sputtering technique as well as by applying combustion CVD methods. For the determination of the photocatalytically properties of the films the decomposition of stearic acid after UV irradiation was investigated by FT-IR measurements. Additionally, measurements of the water contact angles on the surfaces, long-term hydrophilicity measurements and UV-VIS measurements were carried out. It was found for the sputtered films that the photocatalytic properties of the as-deposited films were comparable to commercially available whereas the annealed films showed higher photocatalytic activity. By applying optimal film thicknesses, a strong increase of the transmission value compared to commercially available products could be observed.     

Roentgen contrast media, source for AOX-contamination of waste water by hospitals]

A 30-year-old HIV-positive man presented with acute hydrocephalus secondary to tuberculous meningitis, for which an external ventricular drain was inserted. He developed marked natriuresis in the postoperative period, which resulted in acute hyponatraemia (131 to 122 mmol/l) and a contraction of his intravascular volume. A diagnosis of cerebral salt wasting syndrome was made, and he responded to sodium and fluid loading. This case highlights the differentiation of cerebral salt wasting syndrome from the more commonly occurring syndrome of inappropriate anti-diuretic hormone secretion as the aetiology of the hyponatraemia.