11 research outputs found
Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients
<p>Abstract</p> <p>Background</p> <p>Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia.</p> <p>Methods</p> <p>Human ejaculates were obtained from healthy volunteers and asthenospermic men by masturbation after 4–5 days of abstinence. For determination of cytosolic free calcium concentration, spermatozoa were loaded with the fluorescent ratiometric calcium indicator Fura-2.</p> <p>Results</p> <p>Treatment of spermatozoa from normospermic men with 20 micromolar progesterone plus 1 micromolar thapsigargin in a calcium free medium induced a typical transient increase in cytosolic free calcium concentration due to calcium release from internal stores. Similar results were obtained when spermatozoa were stimulated with progesterone alone. Subsequent addition of calcium to the external medium evoked a sustained elevation in cytosolic free calcium concentration indicative of capacitative calcium entry. However, when progesterone plus thapsigargin were administered to spermatozoa from patients with asthenozoospermia, calcium signal and subsequent calcium entry was much smaller compared to normospermic patients. As expected, pretreatment of normospermic spermatozoa with both the anti-progesterone receptor c262 antibody and with progesterone receptor antagonist RU-38486 decreased the calcium release induced by progesterone. Treatment of spermatozoa with cytochalasin D or jasplakinolide decreased the calcium entry evoked by depletion of internal calcium stores in normospermic patients, whereas these treatments proved to be ineffective at modifying the calcium entry in patients with asthenozoospermia.</p> <p>Conclusion</p> <p>Our results suggest that spermatozoa from asthenozoospermic patients present a reduced responsiveness to progesterone.</p
Wymagania techniczne i praktyczne wskazówki dla stosujących drewno konstrukcyjne lite i klejone w budownictwie
Motor skills, cognitive development and balance functions of children with Down syndrome
Metastasis to the thyroid gland as the first clinical manifestation of lung cancer – case report
Not All Sperm Are Equal: Functional Mitochondria Characterize a Subpopulation of Human Sperm with Better Fertilization Potential
Human sperm samples are very heterogeneous and include a low amount of truly functional gametes. Distinct strategies
have been developed to characterize and isolate this specific subpopulation. In this study we have used fluorescence
microscopy and fluorescence-activated cell sorting to determine if mitochondrial function, as assessed using mitochondrialsensitive
probes, could be employed as a criterion to obtain more functional sperm from a given ejaculate. We first
determined that mitochondrial activity correlated with the quality of distinct human samples, from healthy donors to
patients with decreased semen quality. Furthermore, using fluorescence-activated cell sorting to separate sperm with active
and inactive mitochondria we found that this was also true within samples. Indeed, sperm with active mitochondria defined
a more functional subpopulation, which contained more capacitated and acrosome intact cells, sperm with lower chromatin
damage, and, crucially, sperm more able to decondense and participate in early development using both chemical
induction and injection into mature bovine oocytes. Furthermore, cell sorting using mitochondrial activity produced a more
functional sperm subpopulation than classic swim-up, both in terms of improvement in a variety of functional sperm
parameters and in statistical significance. In conclusion, whatever the true biological role of sperm mitochondria in
fertilization, mitochondrial activity is a clear hallmark of human sperm functionality.Fundação para a Ciência e Tecnologia (POCTI/CVT/49102/2002; SFRH/BD/23571/2005; SFRH/BPD/63120/2009; SFRH/BD/46002/2008; SFRH/BD/46078/2008)Instituto de Investigação Interdisciplinar da Universidade de Coimbra (III/BIO/50/2005
Expression of Estrogen Receptor Coactivator Proline-, Glutamic Acid- and Leucine-Rich Protein 1 within Paraspinal Muscles in Adolescents with Idiopathic Scoliosis
Human gingival fibroblast response to enamel matrix derivative, porcine recombinant 21.3-kDa amelogenin and 5.3-kDa tyrosine-rich amelogenin peptide
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