Membrane dysfunction in Andersen-Tawil syndrome assessed by velocity recovery cycles

Andersen-Tawil syndrome (ATS) due to Kir2.1mutations typically manifests as periodic paralysis, cardiac arrhythmias and developmental abnormalities but is often difficult to diagnose clinically. This study was undertaken to determine whether sarcolemmal dysfunction could be identified with muscle velocity recovery cycles (MVRCs).

Validity of multi-fiber muscle velocity recovery cycles recorded at a single site using submaximal stimuli

To examine the validity of multi-fiber muscle velocity recovery cycles (VRCs) recorded by direct muscle stimulation with submaximal stimuli.

Adiponectin as a marker of success in intracytoplasmic sperm injection/embryo transfer cycles

Adiponectin (Acrp30) is an adipose tissue-derived protein whose serum concentrations, in contrast to leptin, are reported to be negatively correlated to body mass. In spite of the comparatively high circulating adiponectin concentrations, this protein has not been studied in the context of assisted reproduction to date. The aim of this preliminary project was thus to examine the potential of adiponectin to serve as a marker for fertility. We compared adiponectin levels in serum before and after controlled ovarian hyperstimulation, as well as in follicular fluid (FF), between two groups: those with successful outcome (clinical pregnancies) and those with implantation failure. In the former, adiponectin concentrations were higher than in the negative outcome group; this difference was statistically significant (p < 0.05) in serum on the day of oocyte pick-up (OPU) as well as two or three days before OPU, but not in FF or in serum at the beginning of the stimulation phase. This finding adds a new perspective to the suggested but still controversial reduction in FF leptin concentrations in the positive outcome group, and may become a useful tool for early prediction of success of in vitro fertilization treatment for a given patient.

Impact of freezing/thawing procedures on the post-thaw viability of cryopreserved human saphenous vein conduits

BACKGROUND: Cryopreserved human blood vessels are important tools in reconstructive surgery. However, patency of frozen/thawed conduits depends largely on the freezing/thawing procedures employed. METHODS: Changes in tone were recorded on rings from human saphenous vein (SV) and used to quantify the degree of cryoinjury after different periods of exposure at room temperature to the cryomedium (Krebs-Henseleit solution containing 1.8M dimethyl sulfoxide and 0.1M sucrose) and after different cooling speeds and thawing rates following storage at -196 degrees C. RESULTS: Without freezing, exposure of SV to the cryomedium for up to 240 min did not modify contractile responses to noradrenaline (NA). Pre-freezing exposure to the cryomedium for 10-120 min attenuated significantly post-thaw maximal contractile responses to NA, endothelin-1 (ET-1) and potassium chloride (KCl) by 30-44%. Exposure for 240 min attenuated post-thaw contractile responses to all tested agents markedly by 62-67%. Optimal post-thaw contractile activity was obtained with SV frozen at about -1.2 degrees C/min and thawed slowly at about 15 degrees C/min. In these SV maximal contractile responses to NA, ET-1 and KCl amounted to 66%, 70% and 60% of that produced by unfrozen controls. Following cryostorage of veins for up to 10 years the responsiveness of vascular smooth muscle to NA was well maintained. CONCLUSION: Cryopreservation allows long-term banking of viable human SV with only minor loss in contractility.

Velocity recovery cycles of human muscle action potentials and their sensitivity to ischemia

This study was undertaken to test whether recovery cycle measurements can provide useful information about the membrane potential of human muscle fibers. Multifiber responses to direct muscle stimulation through needle electrodes were recorded from the brachioradialis of healthy volunteers, and the latency changes measured as conditioning stimuli were applied at interstimulus intervals of 2-1000 ms. In all subjects, the relative refractory period (RRP), which lasted 3.27 +/- 0.45 ms (mean +/- SD, n = 12), was followed by a phase of supernormality, in which the velocity increased by 9.3 +/- 3.4% at 6.1 +/- 1.3 ms, and recovered over 1 s. A broad hump of additional supernormality was seen at around 100 ms. Extra conditioning stimuli had little effect on the early supernormality but increased the later component. The two phases of supernormality resembled early and late afterpotentials, attributable respectively to the passive decay of membrane charge and potassium accumulation in the t-tubules. Five minutes of ischemia progressively prolonged the RRP and reduced supernormality, confirming that these parameters are sensitive to membrane depolarization. Velocity recovery cycles may provide useful information about altered muscle membrane potential and t-tubule function in muscle disease. Muscle Nerve, 2008.

Intravaginal and intracervical application of seminal plasma in in vitro fertilization or intracytoplasmic sperm injection treatment cycles--a double-blind, placebo-controlled, randomized pilot study

OBJECTIVE: To evaluate whether intravaginal application of seminal plasma at the time of follicle aspiration in IVF or intracytoplasmic sperm injection treatment cycles has the potential to increase pregnancy rate. To calculate the number of patients needed to achieve significance in a multicenter trial. DESIGN: Double-blind, placebo-controlled randomized pilot study. SETTING: University department of gynecological endocrinology and reproductive medicine. PATIENT(S): One hundred sixty-eight patients undergoing IVF or intracytoplasmic sperm injection treatment. INTERVENTION(S): Cryopreserved seminal plasma from the patient's partner or sodium chloride (placebo) was injected into the cervix and the posterior fornix of the vagina just after follicle aspiration. MAIN OUTCOME MEASURE(S): Clinical-pregnancy rate. RESULT(S): One hundred sixty-eight patients agreed to participate in the study. Participation was limited to one treatment cycle. Thirty-one patients (18%) were excluded from the study, mainly as a result of canceled embryo transfers. Seventy patients received placebo, and 67 received seminal plasma. The clinical-pregnancy rate was 25.7% (18/70) in the placebo group. The clinical-pregnancy rate in the seminal plasma group reached 37.3% (25/67), corresponding to a relative increase of 45%. CONCLUSION(S): Even though significance was not reached in this pilot study, the data suggest that seminal plasma has the potential to improve pregnancy rate. It is estimated that around 450 patients need to be recruited to reach significance in a multicenter study.