M. Hammadeh

Surface topography and wetting modifications of PEEK for implant applications

Polyetheretherketone (PEEK) is considered as a substitute for metallic implant materials due to its extremely low elastic modulus (3–4xa0GPa). Despite its good mechanical properties, PEEK exhibits a slow integration with the bone tissue due to its relatively inert surface and low biocompatibility. We introduced a dual modification method, which combines the laser and plasma surface treatments to achieve hierarchically patterned PEEK surfaces. While the plasma treatment leads to nanotopography, the laser treatment induces microstructures over the PEEK surface. On the other hand, plasma and laser treatments induce inhomogeneity in the surface chemistry in addition to the tailored surface topography. Therefore, we coated the structured PEEK surfaces with a thin alumina layer by pulsed laser deposition (PLD) to get identical surface chemistry on each substrate. Such alumina-coated PEEK surfaces are used as a model to investigate the effect of the surface topography on the wetting independent from the surface chemistry. Prepared surfaces bring advantages of enhanced wetting, multiscaled topography, proven biocompatibility (alumina layer), and low elastic modulus (PEEK as substrate), which together may trigger the use of PEEK in bone and other implant applications.

The impact of cigarette smoking on protamines 1 and 2 transcripts in human spermatozoa

Abstract This study was conducted to evaluate the relation between cigarette smoking, semen quality and ratios of protamine mRNAs in smokers and non-smokers. Spermatozoa from 123 men and 64 smokers and 59 non-smokers whose female partners attended an assisted reproduction and andrology laboratory were evaluated. Protamine mRNA was extracted from purified sperm, reverse-transcribed and subjected to real-time quantitative PCR using specific primer pairs for protamine 1 (PRM1) and protamine 2 (PRM2). The main outcomes showed that PRM1 mRNA levels in smokers were significantly lower (pu2009=u20090.05) than that of non-smokers. Additionally, PRM2 mRNA levels in smokers were significantly lower (pu2009=u20090.001) than that of non-smokers. PRM1/PRM2 mRNA ratios in non-smokers samples show significant differences (pu2009=u20090.001) compared with those in smokers. PRM1/PRM2 mRNA ratios were negatively and significantly correlated (pu2009=u20090.001) with semen volume, sperm count and normal sperm morphology. We concluded that sperm quality and sperm protamine mRNAs were negatively affected by smoking, and these data will serve as new evidence for the hazardous effect of smoking on male fertility. Additionally, protamine transcripts ratios may serve as a marker for male fertility.

The status of global DNA methylation in the spermatozoa of smokers and non-smokers

RESEARCH QUESTIONnDoes regular smoking affect semen quality and the levels of DNA methylation in mature human spermatozoa?nnnDESIGNnSpermatozoa from 109 men were evaluated (55 smokers and 54 non-smokers). DNA was extracted from purified spermatozoa, and DNA methylation was quantified by enzyme-linked immunosorbent assay (ELISA).nnnRESULTSnGlobal DNA methylation of non-smokers is significantly lower (Pu202f<u202f0.001) than that of smokers (4.85u202f±u202f2.72 and 7.08u202f±u202f1.77u202fng/μl, respectively). Moreover, the mean global DNA methylation levels were significantly correlated (ru202f=u202f0.22;Pu202f=u202f0.02) with non-condensed chromatin in the spermatozoa. Levels of non-condensed chromatin were significantly higher (Pu202f<u202f0.001) in smokers (29.75u202f±u202f9.38%) compared with non-smokers (20.96u202f±u202f11.31%). Furthermore, global sperm DNA methylation was negatively correlated with high significance (Pu202f<u202f0.010) with sperm: count (ru202f=u202f-0.27), motility (ru202f=u202f-0.30) and vitality (ru202f=u202f-0.26).nnnCONCLUSIONnSmoking interferes with DNA methylation. Also, DNA methylation is significantly correlated with sperm parameters and sperm non-condensed chromatin. These data emphasize another detrimental effect of smoking on male fertility. DNA methylation may, therefore, be considered as a fertility marker in men.

Relationship between nuclear DNA fragmentation, mitochondrial DNA damage and standard sperm parameters in spermatozoa of fertile and sub-fertile men before and after freeze-thawing procedure

The aim of this study was to assess the stability of nuclear and mitochondrial DNA (n‐DNA and mt‐DNA) of spermatozoa under freeze‐thawing and to find out the correlation between them and their association with standard sperm parameters. Forty‐three semen samples were collected from fertile (G.1; n = 29) and sub‐fertile (G.2; n = 14). N‐DNA fragmentation was determined by TUNEL assay and mt‐DNA using caspase 3 staining. Each semen sample was frozen at −196°C by the programmed freezer. Freeze‐thawing decrease vitality, total motility and membrane integrity from (43.02 ± 22.74%; 31.63 ± 18.15%; 51.5 ± 24.82%) to (22.71 ± 17.3%; 9.21 ± 6.61%; 34.64 ± 19.92% respectively [p < .001]). G.1 native spermatozoa stained positive with TUNEL and caspase 3 were (14.85 ± 17.6% and 5.8 ± 11.59%) and increased after freeze‐thawing to 27.54 ± 19.74% (p = .004) and 7.3 ± 6.13% (p = .01) respectively. In G.2, TUNEL and caspase 3 were (19.84 ± 17.52% and 7.53 ± 8.56%) and increased to (29.48 ± 16.97% [p = .03] and 10.21 ± 11.73%). In conclusion, freeze‐thawing process affects not only semen parameters but also n‐DNA and mt‐DNA. Therefore, n‐DNA and mt‐DNA could be used as sensitive parameters for assessment of the cryodamage of human spermatozoa.