Concentrations of homocysteine in follicular fluid and embryo quality and oocyte maturity in infertile women: a prospective cohort.

Homocysteine is one of the components of follicular fluid (FF), so that any disruptions in its concentration may affect oocyte development. The aim of this study was to determine the relationship between FF homocysteine concentration and embryo quality, oocyte maturity, and pregnancy rate. Oocytes and embryos of 44 infertile women were categorised into different groups based on their maturity and quality, respectively. FF homocysteine levels, oocyte maturity, embryo quality, and pregnancy status were measured. A significant association was observed between the levels of FF homocysteine ​and oocyte maturation rate (p = .00). The concentration of FF homocysteine was higher than 9.8 µm/L in women with oocyte maturation < 80%. Most of the good quality embryos belonged to homocysteine levels < 9.8 µm/L. Decreased FF homocysteine concentrations can significantly improve the oocyte maturation rate and embryo quality. Aging may be an indirect factor contributing to decreased embryo quality and oocyte maturation through increasing FF homocysteine levels.IMPACT STATEMENTWhat is already known on this subject? It has been demonstrated that homocysteine is one of the components of follicular fluid (FF), but no information is available about the link between its concentration in FF and oocyte development.What do the results of this study add? The data indicated that decreased FF homocysteine concentrations at a younger age may remarkably improve the oocyte maturity and embryo quality of infertile patients undergoing assisted reproductive treatment (ART).What are the implications of these findings for clinical practice and/or further research? Based on the findings and considering the ease of measuring serum homocysteine and its direct correlation with FF homocysteine, homocysteine level measurement is recommended in patients who are candidates for infertility treatment in order to estimate oocyte maturation rate, embryo quality, and ART outcomes. Future studies are suggested to investigate patients with PCOS, endometriosis, and male factor infertility.

Accelerated nonlinear interactions in graded-index multimode fibers.

Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. As shown in recent studies, the complex nature of such heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we study for the first time, accelerated nonlinear intermodal interactions in core-diameter decreasing multimode fibers. We demonstrate that in the anomalous dispersion region, this spatiotemporal acceleration can lead to relatively blue-shifted multimode solitons and blue-drifting dispersive wave combs, while in the normal domain, to a notably flat and uniform supercontinuum, extending over 2.5 octaves. Our results pave the way towards a deeper understanding of the physics and complexity of nonlinear, heavily multimoded optical systems, and could lead to highly tunable optical sources with very high spectral densities.

Instant and efficient second-harmonic generation and downconversion in unprepared graded-index multimode fibers.

We show that germanium-doped graded-index multimode silica fibers can exhibit relatively high conversion efficiencies (∼6.5%) for second-harmonic generation when excited at 1064 nm. This frequency-doubling behavior is also found to be accompanied by an effective downconversion. As opposed to previous experiments carried out in single- and few-mode fibers where hours of preparation were required, in our system, these χ(2) related processes occur almost instantaneously. The efficiencies observed in our experiments are, to the best of our knowledge, among the highest ever reported in unprepared fibers.

Versatile supercontinuum generation in parabolic multimode optical fibers.

We demonstrate that the pump's spatial input profile can provide additional degrees of freedom in tailoring at will the nonlinear dynamics and the ensuing spectral content of supercontinuum generation in highly multimoded optical fibers. Experiments and simulations carried out at 1550 nm indicate that the modal composition of the input beam can substantially alter the soliton fission process as well as the resulting Raman and dispersive wave generation that eventually lead to supercontinuum in such a multimode environment. Given the multitude of conceivable initial conditions, our results suggest that it is possible to pre-engineer the supercontinuum spectral content in a versatile manner.

Tailoring frequency generation in uniform and concatenated multimode fibers.

We demonstrate that frequency generation in multimode parabolic-index fibers can be precisely engineered through appropriate fiber design. This is accomplished by exploiting the onset of a geometric parametric instability that arises from resonant spatiotemporal compression. By launching the output of an amplified Q-switched microchip laser delivering 400 ps pulses at 1064 nm, we observe a series of intense frequency sidebands that strongly depend on the fiber core size. The nonlinear frequency generation is analyzed in three fiber samples with 50 µm, 60 µm, and 80 µm core diameters. We further demonstrate that by cascading fibers of different core sizes, a desired frequency band can be generated from the frequency lines parametrically produced in each section. The observed frequency shifts are in good agreement with analytical predictions and numerical simulations. Our results suggest that core scaling and fiber concatenation can provide a viable avenue in designing optical sources with tailored output frequencies.

Visible supercontinuum generation in a graded index multimode fiber pumped at 1064 nm.

We observe efficient supercontinuum generation that extends into the visible spectral range by pumping a low differential mode group delay graded index multimode fiber in the normal dispersion regime. For a 28.5 m long fiber, the generated spectrum spans more than two octaves, starting from below 450 nm and extending beyond 2400 nm. The main nonlinear mechanisms contributing to the visible spectrum generation are attributed to multipath four-wave mixing processes and periodic spatio-temporal breathing dynamics. Moreover, by exploiting the highly multimodal nature of this system, we demonstrate versatile generation of visible spectral peaks in shorter fiber spans by altering the launching conditions. A nonlinearly induced mode cleanup was also observed at the pump wavelength. Our results could pave the way for high brightness, high power, and compact, multi-octave continuum sources.

Genotyping of Acanthamoeba isolated from water in recreational areas of Tehran, Iran.

A comprehensive survey assessing the presence of Acanthamoeba was conducted on 50 samples from water sources in parks and public squares from 22 municipal districts of Tehran, Iran. The prevalence and genotypes of Acanthamoeba were determined by PCR and the PCR fragments of ribosomal RNA genes sequenced. Sixteen (32%) samples were positive for Acanthamoeba spp. Sequence analysis revealed that the positive isolates belonged to the T4 and T5 genotypes. Fourteen isolates (87.5%) were T4, and two (12.5%) were T5. Acanthamoeba may be a problematic organism for contact lens wearers and for immunocompromised individuals. In Iran, Acanthamoeba keratitis has increased in recent years, mainly due to poor hygiene in contact lens wearers. A thorough survey for the prevalence of this amoeba could have a significant role in prevention of disease. This is the first report of the T5 genotype from water in recreational areas of Tehran.

Seroprevalence of Acanthamoeba Antibodies in Rheumatoid Arthritis Patients by IFAT, Tehran, Iran 2007.

BACKGROUND: This preliminary study was conducted to discriminate the prevalence of Acanthamoeba antibodies in rheumatoid arthritis (RA) patients and healthy controls to analyze the correlation between these two groups. METHODS: From October 2006 to August 2007 a total of 121 serum samples from RA patients attending the Rheumatolgy Department at Shariati Hospital in Tehran were obtained and stored at -20°C until using by indirect fluorescent-antibody test (IFAT). RA was diagnosed according to the American Collage of Rheumatology classification criteria. The organism used in this study was isolated from various water resources in Tehran, Iran cultured axenically and then went on a PCR assay based on 18S rRNA to identify the genus Acanthomoeba. Indirect immunofluorescence antibody (IFA) staining of serum samples was carried out to detect anti Acanthomoeba antibodies. RESULTS: In culture, out of 22 samples, 13(59%) were grown in xenic but only two in axenic medium. PCR amplified a 904bp fragment, specific for Acanthamoeba. Of examined serum samples, Acanthamoeba antibodies were present in 70 (57.8%) and 52 (41.2%), respectively. The highest titer of antibodies (1:320) was detected in one patient with RA. CONCLUSION: Our study supports the hypothesis that some parasitic microorganisms can involve and contribute toward the development of rheumatoid syndromes.