86,634 research outputs found
Demonstration of receptor-mediated chemotaxis by human spermatozoa. A novel quantitative bioassay.
No full textA novel in vitro technique is described for measuring the chemotactic activity of soluble substances for human spermatozoa. This new bioassay has demonstrated that the synthetic chemotactic peptide N-formyl-Met-Leu-Phe elicits a potent, specific (i.e., receptor-mediated) chemotactic effect on human spermatozoa with an EC50 of 3.2 X 10(-10) M. Quantitative chemotactic studies on human spermatozoa with nine N-formylated-peptide analogs have shown a rank order of peptide potency indistinguishable (p less than 0.001) from that obtained in binding and chemotactic studies with rabbit neutrophils. The competitive antagonist Boc (t-butoxycarbonyl)-Phe-Leu-Phe-Leu-Phe, 10(-6) M, completely inhibited the chemotaxis elicited by f-Met-Leu-Phe, 10(-9) M, and was able to shift by one order of magnitude the molar concentration required by f-Met-Leu-Phe-Phe and f-Met-Leu-Phe to elicit the maximal response. The ability of N-formylated peptides to function as sperm chemoattractants reveals a high degree of correlation with binding, chemotaxis, and lysosomal enzyme release previously employed to define the neutrophil chemotactic receptor. This first unequivocal demonstration of substances having a receptor-mediated chemotactic effect for human male gametes suggests that human spermatozoa may indeed have the ability to respond chemotactically to appropriate environmental signals
"Il Volo di Pègaso" - Raccontare le malattie rare: parole e immagini “Oltre l’ignoto”
No full textSupplemento 1, al n. 1 vol.23 (2010) Notiziario Istituto Superiore di Sanità - ISSN 03949303.
Hanno contribuito alla realizzazione del Secondo concorso artistico-letterario “Il Volo di Pègaso”: per il Centro Nazionale Malattie Rare: Domenica Taruscio(Direttore), Stefania Razeto, Fabiola Gnessi, Davide Varì, Stefano Diemoz;
per il Settore Attività Editoriali:
Paola De Castro (Direttore), Bruno Ballatore, Luigi Nicoletti, Antonio Sesta, Alessandro Spurio,Sandra Salinetti:
Commissione del Secondo concorso “Il Volo di Pegaso”:Cristina Masciola (Sezioni Narrativa e Poesia;Vera Puoti, Gioacchino Loporchio (Sezioni Disegno, Pittura e Scultura); Guido Laudani (Sezioni Fotografia e Cortometraggio
Neuroendocrinologia ed esercizio fisico. Fattori regolanti la liberazione degli ormoni adenoipofisari da stress.
No full textEvidence for the presence of specific receptors for N-formyl chemotactic peptides on human spermatozoa.
No full textSynthetic N-formylated peptides are potent chemoattractants for human spermatozoa in vitro. The specific structure-activity relations for eliciting a chemotactic response and the ability of the antagonist tertbutoxycarbonyl-phenylalanyl-leucyl-phenylalanyl-leucyl- phenylalanine (Boc-Phe-Leu-Phe-Leu-Phe) to inhibit the chemotaxis induced by these peptides strongly suggest the presence of receptors on human spermatozoa. The following studies were performed to identify specific binding sites on human spermatozoa by using [35S]-N-formyl-methionyl-leucyl-phenylalanine [( 35S]f-Met-Leu-Phe), a potent chemotactic peptide. Binding of the [35S]formyl-peptide to human spermatozoa was rapid (t1/2, 8 min) and reversible. Binding isotherms of the saturation experiments revealed a single class of high affinity, low capacity binding sites (equilibrium dissociation constant, 17.7 nM; maximal binding, 109 fmol/2 X 10(6) cells) and an average number of 60,000 receptors per cells. The biological potencies of a series of formyl peptides as chemoattractants correlated closely with their relative abilities to compete with [35S]f-Met-Leu-Phe for specific binding to human spermatozoa. These data fulfill the major criteria for demonstration of specific receptors for chemotactic peptides on human spermatozoa. It is likely that these receptor sites initiate the chemotactic response of human spermatozoa to N-formyl peptides
Lack of endogenous opioid inhibitory tone on LH secretion in early puberty
No full textThirteen normal children, seven males and six females, during early puberty (I-II according to Tanner), have been studied. Each subject was injected at weekly intervals and in random order with 100 μg of LHRH, 0.2 mg/kg of naloxone and 0.9% of saline in single bolus. The gonadotrophin response was evaluated. The administration of naloxone failed to elevate LH levels in any of the subjects studied, even in those who showed a clear gonadotrophin response to LHRH. Unlike the response noted in adults, endogenous opiates do not appear to exert a tonic inhibitory influence on LH secretion during early puberty
Accessibilità e qualità dei servizi socio-sanitari italiani per i pazienti con malattie rare: il parere delle associazioni
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