Highly packed and aligned fluoride substituted hydroxyapatite via a surfactant-free process

Biomolecules and surfactants are believed to be the key factors for reconstruction of tooth enamel and preparation of fluoride hydroxyapatite coating with enamel-like structure on dental implants. We have developed an alternative surfactant-free biomimetic method to stimulate growth of fluoride substituted hydroxyapatite coatings with highly packed and aligned structure on metallic substrates. Oxidized titanium plates were chosen as the substrates. The biomimetic fluoride hydroxyapatite was prepared by immersing the pretreated Ti plates into the phosphate-buffered solution with Ca(2+), H(2)PO(4)(-), HPO(4)(2-), and F(-). The pH value was controlled at 7.4 at the beginning. Every titanium plate (10 mm × 10 mm × 1 mm) was soaked into 20 mL of ion doped phosphate buffered solution in sealed plastic bottles, kept at 37°C or 60°C without stirring for time periods of 1 day to 2 weeks. After immersion, the samples were removed from the solution, rinsed with deionized water and allowed to dry in air. The fluoride substituted hydroxyapatite layer, composed of needle-like crystallites with the diameter of 10-20 nm, was well-organized and tightly packed. XRD results showed a sharper and stronger (002) peak, which could be used to explain that there was a preferable orientation along the c axis. The coating could be reconstructed on the former layer if the mineralization process was repeated, and the structure of the coating could be preserved. The method could be used to construct well organized fluoride substitute hydroxyapatite coating on metal implants.     

Genetic evidence for the presence of two distinct hantaviruses associated with Apodemus mice in Croatia and analysis of local strains

In Europe, Dobrava-Belgrade (DOBV), Saaremaa (SAAV), and Puumala (PUUV) viruses are known to cause hemorrhagic fever with renal syndrome (HFRS). All three hantaviruses are now found in Croatia. Lung tissue samples of 315 Apodemus mice trapped in 2003-2004 were screened for the presence of hantaviral N-Ag and 20 mice (6.3%) were found either strongly positive or weak/suspected-positive. Partial sequences of hantavirus M and S segments were recovered by RT-PCR from six mice and subjected to (phylo)genetic analysis that revealed the presence of four novel strains of DOBV and one of SAAV. Curiously, one of the newly described DOBV strains was found in Apodemus agrarius mouse, that is, not in the traditional host, A. flavicollis mice, suggesting a spillover event. S segment sequences recovered previously from HFRS cases [Markoti? et al., 2002] were confirmed as DOBV sequences; one of which appeared particularly close to the prototype Slovenian DOBV isolate. Taken together with earlier data on PUUV in Croatia, these results show a co-circulation of three European hantavirus pathogens in this country. So far, not a single SAAV sequence has been recovered from HFRS patients either in Croatia or neighboring Slovenia and Hungary nor in Slovakia suggesting a somewhat lower fequency of acute SAAV infection in humans in this part of Europe than for example in the Baltics.     

Long‐TE 1H MRS suggests that liver fat is more saturated than subcutaneous and visceral fat

Cross‐talk between adipose tissue and liver is disturbed in the metabolic syndrome. Moreover, the relative fatty acid composition of adipose and liver fat is poorly characterized. Long‐TE ¹H MRS can determine the unsaturation and polyunsaturation of adipose tissue. The aim of this study was to use long‐TE ¹H MRS to determine the composition of liver fat and its relation to adipose tissue composition. Sixteen subjects with increased liver fat (>5%) were recruited for the study. Using TE = 200 ms, we were able to resolve the olefinic (?CH, 5.3 ppm) and water (H₂O, 4.7 ppm) resonances in liver spectra and to obtain a repeatable estimate of liver fat unsaturation (coefficient of variation, 2.3%). With TE = 135 ms, the diallylic (?C? CH₂? C?, 2.8 ppm) resonance was detectable in subjects with a liver fat content above 15%. Long‐TE ¹H MRS was also used to determine the unsaturation in subcutaneous (n = 16) and visceral (n = 11) adipose tissue in the same subjects. Liver fat was more saturated (double bonds per fatty acid chain, 0.812 ± 0.022) than subcutaneous (double bonds per fatty acid chain, 0.862 ± 0.022, p < 0.0004) or visceral (double bonds per fatty acid chain, 0.865 ± 0.033, p < 0.0004) fat. Liver fat unsaturation correlated with subcutaneous unsaturation (R = 0.837, p < 0.0001) and visceral unsaturation (R = 0.879, p < 0.0004). The present study introduces a new noninvasive method for the assessment of the composition of liver fat. The results suggest that liver fat is more saturated than subcutaneous or visceral adipose tissue, which may be attributed to differences in de novo lipogenesis. Copyright © 2010 John Wiley & Sons, Ltd.     

Human isometric force production and electromyogram activity of knee extensor muscles in water and on dry land

This study was designed to determine trial-to-trial and day-to-day reproducibility of isometric force and electromyogram activity (EMG) of the knee extensor muscles in water and on dry land as well as to make comparisons between the two training conditions in muscle activity and force production. A group of 20 healthy subjects (12 women and 8 men) were tested three times over 2 weeks. A measurement session consisted of recordings of maximal and submaximal isometric knee extension force with simultaneous recording of surface EMG from the vastus medialis, vastus lateralis and biceps femoris muscles. To ensure identical measurement conditions the same patient elevator chair was used in both the dry and the wet environment. Intraclass correlation coefficients (ICC) and coefficients of variation (CV) showed high trial-to-trial (ICC=0.95–0.99, CV=3.5%–11%) and day-to-day reproducibility (ICC=0.85–0.98, CV=11%–19%) for underwater and dry land measurements of force and EMG in each muscle during maximal contractions. The day-to-day reproducibility for submaximal contractions was similar. The interesting finding was that underwater EMG amplitude decreased significantly in each muscle during maximal (P?P?P?P?相似文献   

The response of macrophages to titanium particles is determined by macrophage polarization

Aseptic loosening of total joint replacements is driven by the reaction of macrophages to foreign body particles released from the implant. It was hypothesized that the macrophages’ response to these particles is dependent, in addition to particle characteristics and contaminating biomolecules, on the state of macrophage polarization as determined by the local cytokine microenvironment. To test this hypothesis we differentiated M1 and M2 macrophages from human peripheral blood monocytes and compared their responses to titanium particles using genome-wide microarray analysis and a multiplex cytokine assay. In comparison to non-activated M0 macrophages, the overall chemotactic and inflammatory responses to titanium particles were greatly enhanced in M1 macrophages and effectively suppressed in M2 macrophages. In addition, the genome-wide approach revealed several novel, potentially osteolytic, particle-induced mediators, and signaling pathway analysis suggested the involvement of toll-like and nod-like receptor signaling in particle recognition. It is concluded that the magnitude of foreign body reaction caused by titanium particles is dependent on the state of macrophage polarization. Thus, by limiting the action of M1 polarizing factors, e.g. bacterial biofilm formation, in peri-implant tissues and promoting M2 macrophage polarization by biomaterial solutions or pharmacologically, it might be possible to restrict wear-particle-induced inflammation and osteolysis.     

Intestinal mucosa permeability following oral insulin delivery using core shell corona nanolipoparticles

Chitosan nanoparticles (NC) have excellent capacity for protein entrapment, favorable epithelial permeability, and are regarded as promising nanocarriers for oral protein delivery. Herein, we designed and evaluated a class of core shell corona nanolipoparticles (CSC) to further improve the absorption through enhanced intestinal mucus penetration. CSC contains chitosan nanoparticles as a core component and pluronic F127-lipid vesicles as a shell with hydrophilic chain and polyethylene oxide PEO as a corona. These particles were developed by hydration of a dry pluronic F127-lipid film with NC suspensions followed by extrusion. Insulin nested inside CSC was well protected from enzymatic degradation. Compared with NC, CSC exhibited significantly higher efficiency of mucosal penetration and, consequently, higher cellular internalization of insulin in mucus secreting E12 cells. The cellular level of insulin after CSC treatment was 36-fold higher compared to treatment with free insulin, and 10-fold higher compared to NC. CSC significantly facilitated the permeation of insulin across the ileum epithelia, as demonstrated in an ex vivo study and an in vivo absorption study. CSC pharmacological studies in diabetic rats showed that the hypoglycemic effects of orally administrated CSC were 2.5-fold higher compared to NC. In conclusion, CSC is a promising oral protein delivery system to enhance the stability, intestinal mucosal permeability, and oral absorption of insulin.     

T-lymphocyte subpopulations do not express identical combinations of interleukin-2 receptor chains in the early phase of their activation and proliferation

Owing to the contrasting observations in the field of interleukin(IL)-2 receptor research, the expression of IL-2 receptor chains was analysed on resting and anti-CD3 antibody (OKT3) activated CD4 and CD8 T cells by flow cytometry. Prior to the stimulation, 49% of CD4+ cells expressed IL-2Ralpha (CD25), whereas the expression of IL-2Rbeta (CD122) was very low (8%). The reverse was true for CD8 cells: 48% of them were positive for CD122, but only a fraction (10%) expressed CD25. Practically all lymphocytes expressed IL-2Rgamma (CD132). Interestingly, the unbalanced expression of IL-2Ralpha and -beta continued throughout the stimulation period of 2 days. In addition, the expression of CD45 isoforms in combination with the IL-2R chains and CD71 was followed during the activation of CD4+ T cells. Although CD45RA+/RO- CD4 cells were effectively activated, they retained their naive phenotype up to 2 days of stimulation. On the other hand, CD45RA+low/RO+low (Ddull) CD4+ cells shifted to the memory phenotype rapidly after being activated. However, by day 6 of stimulation the shift of both naive and Ddull cells to memory ones was obvious. The role of the IL-2 receptor in the activation of CD4 subpopulations is discussed.     

Neuropeptide Y polymorphism and alcohol consumption in middle‐aged men

Neuropeptide Y (NPY) plays an important role in the hypothalamic regulation of food intake and energy balance. According to recent findings in animals, NPY also seems to be a potent regulator of alcohol consumption. We used the recently identified Leu(7) to Pro(7) polymorphism in the signal peptide part of NPY to investigate whether the NPY system is associated with alcohol consumption in humans. The subjects (N = 889) were an ethnically homogenous, nonselected population sample of middle‐aged men from Eastern Finland. The gene variant producing Pro(7) substitution was associated with a 34% higher average alcohol consumption, even after adjustment for a number of covariates (P = 0.03). The proportion of heavy drinkers (over 230 g of ethanol/week) was also somewhat higher in this group (13.1% vs. 8.2%, P = 0.10). Our study provides the first evidence that alcohol preference in humans is likely to be regulated by the NPY system. Am. J. Med. Genet. 93:117–121, 2000. © 2000 Wiley‐Liss, Inc.