In cryptozoospermia or severe oligozoospermia is sperm freezing useful?

Background

Intracytoplasmic Sperm Injection (ICSI) is an Assisted Reproduction Technique (ART) which offers the chance to conceive to patients presenting very low sperm counts (cryptozoospermia/severe oligozoospermia). Sperm freezing before the oocyte pick-up, can prevent from a lack of spermatozoa on the day of the ICSI. It can avoid the cancellation of the ICSI or the use of TESE (Testicular sperm extraction). The objective of this study was to analyse the practice of sperm freezing for these patients in our center over 8 years and the rate of use of these frozen sperms. We also compared the outcome of ICSIs with frozen versus ejaculated sperm.

Material and methods

We performed a retrospective epidemiological study between 2004 and 2011. We recruited all the patients having a sperm count below 1 Million/mL and who were waiting for their first ICSI attempt.

Results

169 patients were recruited: 84 cryopreserved their sperm before the ICSI (secured ICSI) while 85 did not (non-secured ICSI). Both groups were split in cryptozoospermia (<10³ spermatozoa/ml): 19 and 17 patients respectively, very severe oligozoospermia (10³–10⁵/ml): 37 and 13 patients, and severe oligozoospermia (10⁵–10⁶/ml): 28 and 55 patients. The part of secured ICSI significantly increased from 29% during 2004–2007 to 74% during 2008–2011(p?=?0.0029) and the frozen sperm was used in 5.9% of the cases. Median age was significantly higher in the non secured ICSI group (33.57 vs 35.52 for men, p?=?0.0069 and 30.45 vs 32.26 for women, p?=?0.025) but no significant difference was found in the outcome of the ICSI between frozen-thawed sperm and fresh ejaculated sperm.

Conclusion

Sperm freezing before ICSI for severe oligozoospermic and cryptozoospermic patients significantly increased in our practice but the rate of use remain very low. This encourages to define more accurate criteria leading to sperm freezing.

     

C-terminal WxL domain mediates cell wall binding in Enterococcus faecalis and other gram-positive bacteria

Analysis of the genome sequence of Enterococcus faecalis clinical isolate V583 revealed novel genes encoding surface proteins. Twenty-seven of these proteins, annotated as having unknown functions, possess a putative N-terminal signal peptide and a conserved C-terminal region characterized by a novel conserved domain designated WxL. Proteins having similar characteristics were also detected in other low-G+C-content gram-positive bacteria. We hypothesized that the WxL region might be a determinant of bacterial cell location. This hypothesis was tested by generating protein fusions between the C-terminal regions of two WxL proteins in E. faecalis and a nuclease reporter protein. We demonstrated that the C-terminal regions of both proteins conferred a cell surface localization to the reporter fusions in E. faecalis. This localization was eliminated by introducing specific deletions into the domains. Interestingly, exogenously added protein fusions displayed binding to whole cells of various gram-positive bacteria. We also showed that the peptidoglycan was a binding ligand for WxL domain attachment to the cell surface and that neither proteins nor carbohydrates were necessary for binding. Based on our findings, we propose that the WxL region is a novel cell wall binding domain in E. faecalis and other gram-positive bacteria.     

Characterization of chromatin-condensing proteins during spermiogenesis in a neogastropod mollusc (Murex brandaris)

During the process of chromatin cndensation in the spermiogenesis of the neogastropod mollusc Murex brandaris, the nuclear protein complement undergoes a complex series of changes. These changes lead to the appearance of three small protamines in the ripe sperm nuclei. We have characterized this system electrophoretically and at the compositions with antibodies elicited against a specific spermatozoan protamine. Our results indicate that the complex pattern of chromatin condensation during spermiogenesis in this species (M. brandaris) may be modulated by a series of post-translational (and intranuclear) modifications of DNA-interacting proteins, such as precursors to the sperm protamines. The amino acid composition of each sperm protamine is remarkably simple (lys + arg + gly ≥96 mol%). This system of spermiogenic/spermatozoal proteins in the neogastropod M. brandaris clearly differs from that in patellogastropods and archaeogastropods, and it may be helpful in understanding evolutionary changes in the chromatin condensation pattern during the spermiogenesis of gastropod molluscs. © 1994 Wiley-Liss, Inc.     

Oligodendrocyte myelin glycoprotein growth inhibition function requires its conserved leucine-rich repeat domain,not its glycosylphosphatidyl-inositol anchor

The oligodendrocyte myelin glycoprotein (OMgp) inhibits neurite outgrowth and axonal regeneration after brain injury, but its normal function remains unknown. Several observations suggest its implication in cell growth regulation. Here we report an analysis of the domain requirement in OMgp proliferation inhibitory function. We first studied the OMgp protein sequence in 14 mammal species and observed a high conservation of its leucine-rich repeat (LRR) domain. The deletion of this LRR domain is responsible for a total loss of function in an in vitro expression system. The possible three-dimensional structure of the LRR domain of OMgp was modelled using the structure of Yersinia pestis YopM cytotoxin as a template. The predicted arrangement of the LRR segments is compatible with a function of OMgp as a binding protein. The OMgp is a glycosylphosphatidyl-inositol-linked protein anchored in the plasma membrane of oligodendrocytes and neurones. Using deletion mutagenesis, we demonstrated the dispensability of the glycosylphosphatidyl-inositol anchor for OMgp proliferation inhibition function. Our results suggest that OMgp is part of a receptor complex, either as a coreceptor or as a membrane-bound or soluble ligand, involved in the transmission of a growth suppressive signal.     

Neurotoxicity of macrophages infected by HIV1

Conclusion Neuronal astrocytes and perhaps oligodendrocytic lesions occur during the course of HIVinfection of CNS cells. Most of the results suggest that these lesions are indirectlyinduced by infected macrophages, probably monocytes, present in the brain. Twomechanisms of neurotoxicity have been studied to date, one testing soluble factors presentin supernatant of infected monocytes and the other the direct effect of adhering HIV-infected monocytes to neurons and astrocytes. These two mechanisms are not mutually exclusive. They both indicate a major role for monocytes in the induction of brain lesionsand the crucial importance of the neurotoxic approach in the study of HIV inducedencephalopathy.     

The Role of Visual Processing Speed in Reading Speed Development

A steady increase in reading speed is the hallmark of normal reading acquisition. However, little is known of the influence of visual attention capacity on children''s reading speed. The number of distinct visual elements that can be simultaneously processed at a glance (dubbed the visual attention span), predicts single-word reading speed in both normal reading and dyslexic children. However, the exact processes that account for the relationship between the visual attention span and reading speed remain to be specified. We used the Theory of Visual Attention to estimate visual processing speed and visual short-term memory capacity from a multiple letter report task in eight and nine year old children. The visual attention span and text reading speed were also assessed. Results showed that visual processing speed and visual short term memory capacity predicted the visual attention span. Furthermore, visual processing speed predicted reading speed, but visual short term memory capacity did not. Finally, the visual attention span mediated the effect of visual processing speed on reading speed. These results suggest that visual attention capacity could constrain reading speed in elementary school children.     

Dynamic aspects of antibody:oligosaccharide complexes characterized by molecular dynamics simulations and saturation transfer difference nuclear magnetic resonance

Carbohydrates are likely to maintain significant conformational flexibility in antibody (Ab):carbohydrate complexes. As demonstrated herein for the protective monoclonal Ab (mAb) F22-4 recognizing the Shigella flexneri 2a O-antigen (O-Ag) and numerous synthetic oligosaccharide fragments thereof, the combination of molecular dynamics simulations and nuclear magnetic resonance saturation transfer difference experiments, supported by physicochemical analysis, allows us to determine the binding epitope and its various contributions to affinity without using any modified oligosaccharides. Moreover, the methods used provide insights into ligand flexibility in the complex, thus enabling a better understanding of the Ab affinities observed for a representative set of synthetic O-Ag fragments. Additionally, these complementary pieces of information give evidence to the ability of the studied mAb to recognize internal as well as terminal epitopes of its cognate polysaccharide antigen. Hence, we show that an appropriate combination of computational and experimental methods provides a basis to explore carbohydrate functional mimicry and receptor binding. The strategy may facilitate the design of either ligands or carbohydrate recognition domains, according to needed improvements of the natural carbohydrate:receptor properties.     

Deletion of TRAAK Potassium Channel Affects Brain Metabolism and Protects against Ischemia

Cerebral stroke is a worldwide leading cause of disability. The two-pore domain K⁺ channels identified as background channels are involved in many functions in brain under physiological and pathological conditions. We addressed the hypothesis that TRAAK, a mechano-gated and lipid-sensitive two-pore domain K⁺ channel, is involved in the pathophysiology of brain ischemia. We studied the effects of TRAAK deletion on brain morphology and metabolism under physiological conditions, and during temporary focal cerebral ischemia in Traak^−/− mice using a combination of in vivo magnetic resonance imaging (MRI) techniques and multinuclear magnetic resonance spectroscopy (MRS) methods. We provide the first in vivo evidence establishing a link between TRAAK and neurometabolism. Under physiological conditions, Traak^−/− mice showed a particular metabolic phenotype characterized by higher levels of taurine and myo-inositol than Traak^+/+ mice. Upon ischemia, Traak^−/− mice had a smaller infarcted volume, with lower contribution of cellular edema than Traak^+/+ mice. Moreover, brain microcirculation was less damaged, and brain metabolism and pH were preserved. Our results show that expression of TRAAK strongly influences tissue levels of organic osmolytes. Traak^−/− mice resilience to cellular edema under ischemia appears related to their physiologically high levels of myo-inositol and of taurine, an aminoacid involved in the modulation of mitochondrial activity and cell death. The beneficial effects of TRAAK deletion designate this channel as a promising pharmacological target for the treatment against stroke.