Trombectomía mecánica en el ictus isquémico agudo, conociendo nuestros resultados / Mechanical thrombectomy in acute ischemic stroke, knowing our results

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Human embryonic stem cells carrying an unbalanced translocation demonstrate impaired differentiation into trophoblasts: an in vitro model of human implantation failure.

Carriers of the balanced translocation t(11;22), the most common reciprocal translocation in humans, are at high risk of creating gametes with unbalanced translocation, leading to repeated miscarriages. Current research models for studying translocated embryos and the biological basis for their implantation failure are limited. The aim of this study was to elucidate whether human embryonic stem cells (hESCs) carrying the unbalanced chromosomal translocation t(11;22) can provide an explanation for repeated miscarriages of unbalanced translocated embryos. Fluorescent in situ hybridization and karyotype analysis were performed to analyze the t(11;22) in embryos during PGD and in the derived hESC line. The hESC line was characterized by RT-PCR and FACS analysis for pluripotent markers. Directed differentiation to trophoblasts was carried out by bone morphogenetic protein 4 (BMP4). Trophoblast development was analyzed by measuring ß-hCG secretion, by ß-hCG immunostaining and by gene expression of trophoblastic markers. We derived the first hESC line carrying unbalanced t(11;22), which showed the typical morphological and molecular characteristics of a hESC line. Control hESCs differentiated into trophoblasts secreted increasing levels of ß-hCG and concomitantly expressed the trophoblast genes, CDX2, TP63, KRT7, ERVW1, CGA, GCM1, KLF4 and PPARG. In contrast, differentiated translocated hESCs displayed reduced and delayed secretion of ß-hCG concomitant with impaired expression of the trophoblastic genes. The reduced activation of trophoblastic genes may be responsible for the impaired trophoblastic differentiation in t(11;22)-hESCs, associated with implantation failure in unbalanced t(11;22) embryos. Our t(11;22) hESCs are presented as a valuable human model for studying the mechanisms underlying implantation failure.

Spindle imaging: a new marker for optimal timing of ICSI?

BACKGROUND: The LC Polscope facilitates visualization of the meiotic spindle in human oocyte. This study aimed to investigate meiotic spindle assembly in correlation to time elapsed after HCG administration, and to determine whether spindle imaging may serve to indicate the likelihood of fertilization and embryo cleavage. METHODS: Metaphase II (MII) oocytes from 103 couples who were being treated for male infertility were imaged with the Polscope prior to sperm injection. Spindle imaging was correlated to time elapsed from HCG administration, fertilization rate and embryo cleavage. The main outcome measures were spindle visualization, fertilization and embryo cleavage on day 3. RESULTS: A total of 770 MII oocytes were imaged. A spindle was imaged in a significantly higher number of oocytes from >or=38 h after HCG administration compared with those in the <38 h group (78.1-81.5% versus 61.6%; P < 0.001). The fertilization rate in oocytes with a visible spindle was statistically higher compared with oocytes in which spindle could not be detected (70.4% versus 62.2%; P = 0.035). We found no relationship between spindle imaging and embryo cleavage on day 3. CONCLUSIONS: Spindle imaging, in addition to first polar body appearance, is an accurate indicator for oocyte maturity. We suggest that spindle imaging be performed prior to sperm injection.

Solid-phase PCR in microwells: effects of linker length and composition on tethering, hybridization, and extension.

During the solid-phase PCR (SP-PCR), DNA oligonucleotides complementary to a soluble template and immobilized on a surface are extended in situ. Although primarily used for pathogen detection, SP-PCR has the potential for much broader application, including disease diagnostics, genotyping, and expression studies. Current protocols for SP-PCR in microwells are suitable for enzymatic detection of immobilized products, but yields are generally insufficient for direct detection of products using conventional fluorescent probes. Here, we quantitatively measure the outcome of tethering, hybridization, and solid-phase extension, and examine the effect of composition and length of the spacer at the 5' end of tethered oligonucleotides. Our results indicate that steric hindrance primarily affects polymerase activity rather than the efficiency of hybridization between the template and the tethered oligonucleotide. SP-PCR yields are significantly higher for a five-unit hexaethyleneglycol (HEG) spacer than for the more commonly used 10-residue deoxythymidine spacer. The optimal 5' HEG spacer resulted in a 60-fold increase in extension efficiency relative to a previously reported value for SP-PCR on a glass surface. Thus, optimized spacers should allow direct quantification of SP-PCR products, providing a simple, quantitative, and cost effective means of sample analysis for a variety of applications.

A new animal model for action myoclonus.

Morphine was injected into a catheter implanted chronically into the intrathecal space of rats. Three to eight minutes after drug administration, 80% of the rats developed arrhythmic stimulus-sensitive jerks that lasted up to 1 hr. The morphine-induced myoclonic activity was markedly reduced by naloxone. Methadone, pethidine, and etorphine failed to produce the syndrome. In spinally transected rats, morphine injected below the level of transection did not produce the syndrome. No significant changes in PaCO2 and PaO2 were produced by morphine before and throughout the period of myoclonic activity. Neither did induced hypoxia augment the effect of morphine. However, irreversible hypoxic-ischemic cell changes were noticed in some brain regions. The phenomenon described here resembles the human syndrome of action myoclonus and may serve as an animal model for studying the mechanism of that neurological disorder.

Effect of alpha-chlorohydrin on metabolism and testosterone secretion by rat testicular interstitial cells.

The direct effect of alpha-chlorochydrin (alpha-CH) on basic metabolism (glucose utilization and oxygen consumption) and testosterone secretion by isolated rat interstitial cells (I-cells) has been studied. In the range of concentrations between 5 and 100 microliter/ml, only the highest doses of alpha-CH decreased cell vitality and their histochemical stain for 3 beta-HSD. Oxygen consumption of I-cells was depressed at all doses higher than 10 microliter/ml and this effect was reversible only with doses lower than 50 microliter/ml. glucose utilization by I-cells was depressed significantly by alpha-CH and this effect was particularly dramatic with doses higher than 50 microliter/ml. alpha-CH decreased testosterone secretion by I-cells, with maximal effects at 100 microliter/ml. I-cells responded to hCG challenge by increasing testosterone secretion, and hCG prevented the toxic effect of alpha-CH at the lowest dose (10 microliter/ml) of alpha-CH, but failed to overcome the effects of a high dose (100 microliter/ml).

Rhythm length and hemispheric asymmetry.

Conflicting evidence has appeared in the literature concerning hemispheric asymmetry in the perception of rhythm. The present study investigated the effects of rhythm length on relative cerebral dominance. Twenty-four subjects were presented with sequences of one to four time intervals bounded by light flashes. The subjects' task was to determine if two such sequences were the same or different. The first rhythm was presented in both visual fields and the second only to one visual field. Reaction times and number of errors were recorded. It was found that increasing rhythm length resulted in a shift in cerebral dominance from left to right hemisphere. An interpretation of these findings was suggested in terms of the preferred mode of processing of each hemisphere, analytic vs. holistic.

A model for the temperature distribution in skin noxiously stimulated by a brief pulse of CO2 laser radiation.

The application of localized noxious heat stimuli to the skin, generated by brief infrared radiation pulses emitted by a CO2 laser, is a relatively new experimental technique for the thermal induction of pain in humans and in experimental animals. This study proposes a model for the spatial (3-dimensional) and temporal distribution of the skin temperature during and following a radiation pulse. The heat equation is written and solved, using thermal and optical constants of human skin reported in the literature. The solution is approximated, with a very small error, by a closed form expression, having a simple physical interpretation. This model is applied to analyze a typical set-up currently in use in our laboratory. The results show a significant difference between the temperature of the surface of the skin and that of the border between the epidermis and the dermis, which is the location of the most superficial receptive nerve ends. It is shown that, for the set-up examined, these nerve ends reach a temperature of 45 degrees C, known to be the human pain threshold, 30-40 ms after pulse onset. Moreover, it is also shown that they may remain above threshold temperature for up to a few hundreds of milliseconds (considerably outlasting pulse cessation). In addition, it is shown that the area in which nerve ends reach this threshold is a circle with a very small radius (1-2.5 mm). The implications of the results on the double sensation experienced by humans, and on the extremely powerful EEG correlates, are discussed.

Somatosensory evoked potentials and noxious stimulation in patients with intractable, noncancer pain syndromes.

Investigations of the evoked potentials (EPs) to noxious laser stimulation have indicated consistent strong linear relationships between subjective response (R), stimulus intensity (S), and EP amplitude (A). Thirty patients with chronic intractable benign pain syndromes (CIBPS) were tested to determine whether their patterns differed from previous studies with normal volunteers. Nearly half of the CIBPS patients were found to be relatively insensitive to acute pain stimuli. A large number were also found to show negative relationships between S and A. These differences from control subjects were considered of potential importance in their implications concerning the nature of chronic pain and its differences from the acute pain process.

Peripheral fiber correlates to noxious thermal stimulation in humans.

Minimal conduction velocities of peripheral nerves contributing to acute thermal pain sensation in human volunteer subjects were calculated. Purely thermal stimulation was administered by a low power laser beam directed at the subjects' fingers, and subjective pain responses correlated with a peak in the event-related brain potential (ERBP). These cerebral responses were found to preclude C fiber peripheral activity from this phenomenon.

Single trial analysis of evoked potentials to noxious thermal stimulation in man.

Thermal (laser) evoked responses were obtained from 13 male volunteers. A single trial analysis technique with a latency adjusting adaptive filter was used to analyze evoked response amplitudes. Significant and substantial within-subject linear correlations were found between the magnitude (A) of the primary waveform (RMS muV of the P200--N300-P400 complex ) and subjective pain response (R) as well as stimulus intensity (S). Since subjective pain response was strongly correlated with stimulus intensity, the partial correlation coefficients were calculated for R vs. A with S controlled, and S vs. A with R controlled, for each subject. The partial correlations revealed a much stronger relationship between subjective response and the evoked response amplitude, suggesting that the primary complex may measure neural events in the pain perception process rather than transduction and transmission of the stimulus event.