Reproducibility of peak power output during a 10-s cycling maximal effort using different sampling rates.

The study was aimed to investigate the reproducibility of performance parameters obtained from 10-s maximal cycling effort against different braking forces in young adult athletes. The sample (n = 48) included male athletes aged 18.9-29.9 years (175.5 ± 6.9 cm, 76.2 ± 10.1 kg). The exercise protocol was performed in a cycle-ergometer against a random braking force (4% to 11% of body mass). Intra-individual variation was examined from repeated tests within one week. Descriptive statistics were computed and differences between sessions were tested using paired t-test. The coefficient of correlation between repeated measures, technical error of measurement (TEM), coefficient of variation and ICC were calculated. Agreement between trials was examined using the Bland-Altman procedure. Mean values of peak power were relatively stable when obtained from sampling rates of 50 Hz and ranged between 1068 watt and 1082 watt (t(47) = 1.149, p = 0.256, ES-r = 0.165) or while corresponding to a sampling rate of 1 Hz (t(47) = 0.742, p = 0.462, ES-r = 0.107). Correlations between repeated measures were high (+0.907, 95% CI: +0.839 to +0.947) and TEM about 59.3 watt (%CV = 5.52%; ICC = 0.951, 95% CI: 0.912 to 0.972). The present study suggests that reproducibility of peak power in male adult athletes tended to be acceptable and within individual error appeared unrelated to braking force.

Insulin-like growth factor binding proteins 4 and 7 released by senescent cells promote premature senescence in mesenchymal stem cells.

Cellular senescence is the permanent arrest of cell cycle, physiologically related to aging and aging-associated diseases. Senescence is also recognized as a mechanism for limiting the regenerative potential of stem cells and to protect cells from cancer development. The senescence program is realized through autocrine/paracrine pathways based on the activation of a peculiar senescence-associated secretory phenotype (SASP). We show here that conditioned media (CM) of senescent mesenchymal stem cells (MSCs) contain a set of secreted factors that are able to induce a full senescence response in young cells. To delineate a hallmark of stem cells SASP, we have characterized the factors secreted by senescent MSC identifying insulin-like growth factor binding proteins 4 and 7 (IGFBP4 and IGFBP7) as key components needed for triggering senescence in young MSC. The pro-senescent effects of IGFBP4 and IGFBP7 are reversed by single or simultaneous immunodepletion of either proteins from senescent-CM. The blocking of IGFBP4/7 also reduces apoptosis and promotes cell growth, suggesting that they may have a pleiotropic effect on MSC biology. Furthermore, the simultaneous addition of rIGFBP4/7 increased senescence and induced apoptosis in young MSC. Collectively, these results suggest the occurrence of novel-secreted factors regulating MSC cellular senescence of potential importance for regenerative medicine and cancer therapy.

The serotonin receptor 7 promotes neurite outgrowth via ERK and Cdk5 signaling pathways.

Serotonergic neurotransmission is mediated by at least 14 subtypes of 5-HT receptors. Among these, the CNS serotonin receptor 7 (5-HTR7) is involved in diverse physiological processes. Here we show that treatment of murine striatal and cortical neuronal cultures with 5-HTR7 agonists (8-OH-DPAT and LP-211) significantly enhances neurite outgrowth. This effect is abolished by the selective 5-HTR7 antagonist SB-269970, by the ERK inhibitor U0126, by the cyclin-dependent kinase 5 (Cdk5) inhibitor roscovitine, as well as by cycloheximide, an inhibitor of protein synthesis. These data indicate that 5-HTR7 activation stimulates extensive neurite elongation in CNS primary cultures, subserved by ERK and Cdk5 activation, and de novo protein synthesis. Two-dimensional (2D) gel electrophoresis coupled to Western blot analyses reveals both qualitative and quantitative expression changes in selected cytoskeletal proteins, following treatment of striatal primary cultures with LP-211. In particular, the 34 kDa isoform of MAP1B is selectively expressed in stimulated cultures, consistent with a role of this protein in tubulin polymerization and neurite elongation. In summary, our results show that agonist-dependent activation of the endogenous 5-HTR7 in CNS neuronal primary cultures stimulates ERK- and Cdk5-dependent neurite outgrowth, sustained by modifications of cytoskeletal proteins. These data support the hypothesis that the 5-HTR7 might play a crucial role in shaping neuronal morphology and behaviorally relevant neuronal networks, paving the way to new approaches able to modulate CNS connectivity.

Structural analysis of toxic volkensin, a type 2 ribosome inactivating protein from Adenia volkensii Harm (kilyambiti plant): molecular modeling and surface analysis by computational methods and limited proteolysis.

Volkensin, isolated from Adenia volkensii, is one of the most toxic type 2 ribosome-inactivating protein (RIP), exerting its biological function by inhibiting protein synthesis. Despite the high sequence identity with type 2 RIPs, including ricin, volkensin shows interesting peculiar properties. In this work a computational model building of volkensin was performed. The volkensin electrostatic potential charge distribution, the hydrophobic profile and the surface topology analyses were also carried out to aid the understanding of structure-function relationships of this potent toxin. Volkensin surface topology was probed by applying a limited proteolysis approach with the aim to gain insights into volkensin conformational features.

Precursor ion discovery on a hybrid quadrupole-time-of-flight mass spectrometer for gonadotropin-releasing hormone detection in complex biological mixtures.

The gonadotropin-releasing hormone (GnRH) family includes several hypophysiotropic peptides occupying a central position in the regulatory loop controlling reproduction. Studies are still under way to clarify its biological role and evolutionary implication. Although sequencing of multiple genomes is bringing further advances in the understanding of the evolution of GnRH, there is still a need for biochemical studies aiming to identify GnRH from different species. Using a hybrid quadrupole-time-of-flight (Q-TOF) instrument, a new method for selective and sensitive GnRH detection and characterization from tissue extracts has been developed. The method uses the "precursor ion discovery" mode based on the capability of the Q-TOF analyzer to quickly record alternate mass spectra at low and high collision energy of precursor and product ion spectra, respectively, following liquid chromatographic separation of complex biological mixtures. The method exploits the selective detection of a specific b(2) product ion at m/z 249.1, corresponding to the N-terminus dipeptide pyroglutamic acid-histidine, highly conserved among nearly all species (22 of 24), and deriving from the preferential fragmentation of GnRHs carrying the dipeptide. Importantly, the method also includes acquisition of the product ion spectra from any candidate precursor ion, thereby allowing the determination of sequence information to confirm the GnRH identity or to isolate new ones.

Kidney transplantation from donors with viral B and C hepatitis.

INTRODUCTION: The success of renal transplantation as a treatment for end-stage renal disease has created a chronic shortage of donor organs. We present our experience in transplanting kidneys from donors with hepatitis B virus (HBV) or hepatitis C virus (HCV) among matched serology-positive recipients. MATERIALS AND METHODS: From January 2002 to November 2005, 44 patients with end-stage renal disease and HCV seropositivity underwent kidney transplantation. In 28 transplants in HCV+ recipients, the donor was HCV+ (DC+/RC+) and in 16 of these cases the donor (one living donor) was HCV- (DC-/RC+). In the same period 14 patients with HBV infection and HbsAg seropositivity underwent kidney transplantation: eight received their graft from a cadaveric HbsAg-positive donor (DB+/RB+), while six patients received their graft from an HbsAg-negative donor. RESULTS: Viral reactivation was higher among DC+/RC+ (21.4%) than DC-/RC+ patients (6%). Graft survivals were 90% and 88% for DC+/RC+ and DC-/RC+, respectively; patient survivals were 100% for DC+/RC+ and 94% for DC-/RC+. Among the group of DB+/RB+, all the patients developed an HBV-DNA positivity in the early postoperative period. Patient and graft survivals were 100% in both groups. CONCLUSIONS: Our results suggest that HBV- and HCV-positive donors can be considered as an alternative donor source, because their kidneys are allocated to the matched serology-positive recipients, shortening their time on the waiting list.

Caspofungin in the treatment of azole-refractory esophageal candidiasis in kidney transplant recipients.

BACKGROUND: Infection is a common cause of morbidity and mortality in kidney transplant recipients. The incidence of esophageal and urogenital candidiasis in kidney and kidney-pancreas transplant recipients has not been well documented. Azoles are safe, effective agents to treat esophageal candidiasis. However, resistance to azoles is now becoming common. This study reports the use of caspofungin for the treatment of azole-resistant esophageal and urogenital candidiasis in kidney transplant recipients. PATIENTS AND METHODS: The incidence of esophageal and urogenital candidiasis was evaluated among 140 kidney transplantations and four combined kidney-pancreas transplants performed over a 2-year period. RESULTS: Twenty-two patients (15.7%) presented with esophageal candidiasis, while seven patients (5%) showed urogenital candidiasis. Thirteen patients with esophageal candidiasis (59%) and four patients (57%) with urogenital candidiasis did not improve after a week of azole treatment. A regimen of caspofungin was started in these patients, who tolerated the treatment. Urogenital candidiasis recurred in two patients 2 and 3 months after the treatment. One patient with esophageal candidiasis did not improve with caspofungin and was switched to amphotericin B therapy. There were no other recurrences of candidiasis among patients treated with caspofungin for a median follow-up of 8 months. CONCLUSIONS: Renal transplant patients remain at high risk for fungal infections. Although the number of patients was limited, the results of this study indicated that caspofungin is an effective, well-tolerated alternative for difficult-to-treat, azole-resistant candida infections in kidney and pancreas transplant recipients. The high costs of the drug limit the use of caspofungin as first-line antifungal therapy, reserving its use to recipients who had undergone unsuccessful azole therapy.

Occupational hypersensitivity to metal salts, including platinum, in the secondary industry.

BACKGROUND: Exposure to platinum group elements (PGEs) - platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir) - may cause acute toxicity or hypersensitivity with respiratory symptoms, urticaria and (less frequently) contact dermatitis. Our aim was to determine the prevalence and the clinical characteristics of hypersensitivity to platinum salts and to other elements of the platinum group. METHODS: A total of 153 subjects working in a catalyst manufacturing and recycling factory were examined. The examination consisted of a work exposure and medical questionnaire, physical examination, skin prick test for PGEs and other common aeroallergens, and patch tests for PGEs. Skin prick tests and patch tests were performed with H(2)[PtCl(6)], K(2)[PtCl(4)], Na(2)[PtCl(6)], IrCl(3), RhCl(3), PdCl(2), aqueous solutions at different concentrations. RESULTS: Positive prick test reactions to Pt-salts at various concentrations were found in 22 (14.4%) of 153 workers; eight had simultaneous reactions to all Pt-salts tested; seven had positive responses to H(2)[PtCl(6)] only; four had simultaneous positive reactions to both H(2)[PtCl(6)] and K(2)[PtCl(4)]; three had positive reactions to H(2)[PtCl(6)] and Na(2)[PtCl(6)]. Three of 22 had positive reactions to H(2)[PtCl(6)] and IrCl(3) solutions, two of these had positive reactions to H(2)[PtCl(6)], IrCl(3) and RhCl(3) solutions. Positive patch test reactions to platinum salts at day 2 were seen in two of 153 subjects. CONCLUSIONS: The results of this study demonstrate that Pt-salts are important allergens in the catalyst industry and that the clinical manifestations involve both the respiratory system and the skin. Hexachloroplatinic acid should be considered the most important salt to use for skin prick tests.