The study of metal ion release and cytotoxicity in Co–Cr–Mo and Ti–Al–V alloy in total knee prosthesis – scanning electron microscopic observation

We surgically retrieved two cobalt(Co)–chromium(Cr)–molybdenum(Mo) and five titanium(Ti)–aluminum(Al)–vanadium(V) alloy knee prostheses from patients because of mechanical failure and pain. We examined the distribution of the small particles which were released from the Co–Cr–Mo and Ti–Al–V alloys using a backscattered scanning electron microscopy (SEM). In addition we analyzed the metals in the artificial knee joints and the tissues adjacent to them using energy dispersive X-ray spectroscopy (EDS). We demonstrated that a myriad of fine particles, produced by the abrasion of both Co–Cr–Mo and Ti–Al–V alloys, accumulated in the synovial cells. As Co–Cr–Mo alloys disintegrate easily in the cells, Co dissolves from the peripheral areas of them, although Cr remains within the cells. In contrast Ti–Al–V alloys are very stable in the synovial cells. From these findings we conclude that the Co–Cr–Mo alloys are hazardous to the body as the alloys release Co which enters the body. In contrast the Ti–Al–V alloys are very stable and are patently safer. Artificial joints, however, are still in considerable need of improvement.     

Recombination and Pol ζ Rescue Defective DNA Replication upon Impaired CMG Helicase—Pol ε Interaction

The CMG complex (Cdc45, Mcm2–7, GINS (Psf1, 2, 3, and Sld5)) is crucial for both DNA replication initiation and fork progression. The CMG helicase interaction with the leading strand DNA polymerase epsilon (Pol ε) is essential for the preferential loading of Pol ε onto the leading strand, the stimulation of the polymerase, and the modulation of helicase activity. Here, we analyze the consequences of impaired interaction between Pol ε and GINS in Saccharomyces cerevisiae cells with the psf1-100 mutation. This significantly affects DNA replication activity measured in vitro, while in vivo, the psf1-100 mutation reduces replication fidelity by increasing slippage of Pol ε, which manifests as an elevated number of frameshifts. It also increases the occurrence of single-stranded DNA (ssDNA) gaps and the demand for homologous recombination. The psf1-100 mutant shows elevated recombination rates and synthetic lethality with rad52Δ. Additionally, we observe increased participation of DNA polymerase zeta (Pol ζ) in DNA synthesis. We conclude that the impaired interaction between GINS and Pol ε requires enhanced involvement of error-prone Pol ζ, and increased participation of recombination as a rescue mechanism for recovery of impaired replication forks.     

Speciation-capable field instrument for the measurement of arsenite and arsenate in water

Hydride generation to form arsine and in-line preconcentration of the arsine into an alkaline KMnO4 receiver followed by molybdenum blue (MB) colorimetric determination of the arsenate formed is proposed for the highly sensitive and separate measurement of total inorganic As and As(III). Reduction of As to AsH3 is carried out by NaBH4; when the reduction is carried out at pH 1, all the inorganic As is reduced to AsH3, and when carried out at pH 7, only As(III) is reduced. Reductions at the two different pH levels are carried out in two different arsine generators simultaneously using constant addition of NaBH4 with solenoid pumps. The AsH3 is collected by individual porous membrane diffusion scrubbers filled with a stationary solution of KMnO4, and the contents of the two scrubbers sequentially enter a flow analysis stream. MB is formed by merging with a ammonium molybdate-ascorbic acid reagent, passing through a heated reactor, and is then measured by a LED/photodiode-based absorbance detector. Robustness was confirmed for total As using three types of certified natural water samples. Speciation analysis data from well water samples analyzed by this method agree well with HPLC-ICPMS measurements in a different laboratory. The system has been successfully applied to field measurements of As(III) and As(V), where levels were significantly below 1 mug/L. For a 20-mL sample, the limits of detection (LODs) for this inexpensive instrument are 0.3 microg/L for both As(III) and total As. When an 80-mL sample is analyzed, LODs are 0.07 microg/L As(III) and 0.09 microg/L total As. The general approach should be applicable to many other analyte species of interest that can be isolated from the matrix by the formation of a suitable volatile compound that can be recaptured.     

Renal Cyclooxygenase Products are Higher and Lipoxygenase Products are Lower in Early Disease in the pcy Mouse Model of Adolescent Nephronophthisis

Nephronophthisis (NPHP) is a pediatric form of hereditary polycystic kidney disease (PKD), and is the leading cause of end stage renal disease in children. The pcy mouse is an orthologous model of human NPHP, with a mutation in the Nphp3 gene. Renal phospholipase A₂, cyclooxygenase (COX) 1 and cyclic AMP are elevated in this model, suggesting that eicosanoid formation may be altered. In another type of PKD observed in the Han:SPRD-Cy rat, inhibition of eicosanoid production slows disease progression. If renal eicosanoids are similarly altered in NPHP, potential for pharmacologic intervention also may exist for this disorder. Therefore, renal fatty acids and eicosanoids were determined in pcy and normal mice at 15, 30 and 60 days of age by gas chromatography and HPLC–tandem mass spectrometry, respectively. Renal cysts in enlarged kidneys were observed in pcy mice by 15 days of age and increased over time. Renal phospholipid ARA levels were higher in pcy compared to normal mice at 15 and 30 days. Eicosanoid differences were observed starting at 30 days, when the COX products 6-keto-prostaglandin (PG) F_1α, thromboxane B₂ and PGE₂ were higher in pcy compared to normal kidneys. Overall, total COX products were elevated at 30 and 60 days. In contrast, the levels of the lipoxygenase (LOX) products were not altered until 60 days of age and these were lower in pcy kidneys compared to normal. These findings suggest that altered eicosanoids play a role in NPHP, and that manipulating these levels with pharmacologic agents may have therapeutic potential.     

Long-term effect of an enteral diet with a different n-6/n-3 ratio on fatty acid composition and blood parameters in rats

The n-6/n-3 ratio of polyunsaturated fatty acids (PUFAs) in enteral feeding formulas is not considered to be important, because the short-term administration of these formulas has been the norm for postoperative digestive organs. However, the long-term administration of enteral feeding formulas has been increasingly recommended for patients with aging-associated aphagia. This study is aimed at investigating the effect of the long-term administration of an enteral feeding formula containing n-3 polyunsaturated fatty acids (PUFAs) on the fatty acid composition of endogenous phospholipids. Rats, which were initially fed a diet lacking n-3 PUFAs for 2 generations, were subsequently fed an enteral feeding formula containing or lacking n-3 PUFAs for 12 weeks (n = 10). Then, the fatty acid composition of phospholipids in the brain, liver, red blood cells, and plasma of the rats was analyzed. Although the fatty acid composition of neural tissues is suggested to be not affected by diet, the n-6/n-3 ratio of phospholipids in the brains of rats that were fed an enteral feeding formula containing n-3 PUFAs was significantly lower than those of rats that were fed a formula lacking n-3 PUFAs. The enteral feeding formula containing n-3 PUFAs may be effective for the regulation of brain functions and the prevention of atherosclerosis.     

Formation of a mental abacus for computation and its use as a memory device for digits: A developmental study.

In order to examine whether representational changes in digit memory would be observed as a function of the extent of expertise in mental-abacus operation, five groups of operators, differing in extent of expertise (i.e., novices, lower intermediates, intermediates, junior experts, and experts), were required (a) to reproduce series of five digits either forward or backward as quickly as possible and (b) to perform a simple aural-verbal or visual-spatial task interpolated between the presentation and reproduction of a near-span series of digits. The intermediates and more skilled operators as well as a majority of the lower intermediates showed nearly equal amounts of time for forward and backward reproduction, whereas novices took a much longer time for backward than for forward reproduction. The more skilled operators were, the less vulnerable was their memory for digits to the aural-verbal interpolated task (a relation that was significant) and the more vulnerable to the visual-spatial task (a relation that was insignificant). These results strongly suggest that the advanced operators applied their mental abacus to digit memory. It is claimed that a system of representation formed through routine problem solving is transferred automatically to other cognitive tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scanning electron microscopy and energy-dispersive X-ray analysis of self-etching adhesive systems to ground and unground enamel

The morphological analysis of the ground and unground enamel was treated with three different self-etching adhesive systems. Ultrastructural features were observed by using the field emission scanning electron microscope (FESEM) in combination with Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Thirty extracted human molars were used for this study. Teeth were divided into two groups. In the first group unground enamel was etched with either Clearfil SE Bond (Kuraray-Japan), G Bond (GC-Japan) or Tri S Bond (Kuraray-Japan) according to the manufactures instructions. In the second group ground enamel was treated as above. In addition 24 ungrounded and grounded enamel specimens were etched and bonded with the three self-etching adhesives and restored with composite resin (Clearfil ST-Kuraray). Then they were cross-sectioned and interfacial analysis was done with the combination of EDS analysis. Etching patterns of the enamel varied according to the self-etching adhesive. Clearfil SE Bond produced micro-irregular etching pattern creating crater like area in ground enamel while other two produced mild etching pattern. All three adhesives produced incomplete etching on unground enamel. Interfacial studies showed demineralization for the bonding agent penetration and the formation of hybrid layer. The self-etching adhesives produced different specific SEM morphologies on unground and ground enamel.     

Specific response of osteoblast-like cells on hydroxyapatite layer containing serum protein

Accelerations of bone-like apatite deposition and cell growth on an electrically polarized ceramic hydroxyapatite have been reported. A relationship between these phenomena was investigated in a previous report, and then it was suggested that osteoblast-like cell’s (MC3T3-E1) growth had relevance to the mineral growth. The effect of the formed apatite layer especially appeared to be on the cell adhesion. The acceleration of cell proliferation on the polarized HAp has been shown using fibroblastic cell (L929) and nerve cell (SK-N-SH) lines, therefore the effect of the layer on L929 and SK-N-SH was investigated to support the mechanism of acceleration of cell proliferation by polarization of HAp. In this study, the effect of the bone-like apatite layer was not confirmed on L929 cell’s growth. On the other hand, the acceleration of nerve cell’s proliferation was confirmed on the formed apatite layer. However, the remarkable improvement of the cell adhesion of SK-N-SH was not confirmed on the apatite layer. Consequently, it was considered that the bone-like apatite containing serum protein obtained by the coprecipitation of bone-like apatite and serum protein has a pronounced role only in the activity of osteoblast-like cells.