An EPR investigation of spin-labelled erythrocytes as a diagnostic technique for malignant hyperthermia.

Spin labelled (7-, 12- and 16- doxylsteric (DS) acid) erythrocyte (red blood cell) membranes isolated from six malignant hyperthermia susceptible (MHS) and six malignant hyperthermia normal (MHN) volunteer donors were characterized using the order parameter (S) and rotational correlation time (tau r) determined from 37 degrees C, 9 GHz electron paramagnetic resonance spectra. These parameters were found to decrease due to the increasing fluidization of the membrane as the halothane and benzyl alcohol sample concentration is increased and that significant differences exist in the values of S and tau r between the MHS and MHN sample groups, but that the differences in these parameters between the presence and absence of an external fluidizing agent are not significant for both sample groups. In the absence of these fluidizing agents, the mean values and standard errors of S at 37 degrees C for MHS and MHN are 0.643(2) and 0.652(3) for 7-DS, 0.554(2) and 0.563(3) for 12-DS, respectively, and of tau r are 2.139(12) and 2.223(13) ns for 16-DS, respectively. The values of S and tau r are significantly smaller for the MHS group than for the MHN group contrary to some previous reports. These observations revise and extend previous reports and show that the observed values of S and tau r in the absence of a fluidizing agent depend on the erythrocyte membrane structure in MHS and MHN subjects. They also suggest that the potential to use spin-labelled red blood cells as a screening protocol for MH deserves further investigation.     

Developing a hybrid weed risk assessment system for countries with open and porous borders: insights from Bhutan

Biological Invasions - Intentional introduction of alien plant species through increased global trade and movement of people worldwide has contributed to the current problem of invasion by alien...     

Laboratory animal models of temporal lobe epilepsy

Temporal lobe epilepsy is a common human disease that is difficult to treat. The pathogenesis of temporal lobe epilepsy, which holds many unresolved questions, and opportunities for creating more effective treatments and preventative strategies are reviewed herein. Laboratory animal models are essential to meet these challenges. How models are created, how they compare with each other and with the disease in human patients, and how they advance our understanding of temporal lobe epilepsy are described.     

Increasing length of wakefulness and modulation of hypocretin-1 in the wake-consolidated squirrel monkey

The neuropeptides hypocretins (orexins), the loss of which results in the sleep disorder narcolepsy, are hypothesized to be involved in the consolidation of wakefulness and have been proposed to be part of the circadian-driven alertness signal. To elucidate the role of hypocretins in the consolidation of human wakefulness we examined the effect of wake extension on hypocretin-1 in squirrel monkeys, primates that consolidate wakefulness during the daytime as do humans. Wake was extended up to 7 h with hypocretin-1, cortisol, ghrelin, leptin, locomotion, and feeding, all being assayed. Hypocretin-1 (P < 0.01), cortisol (P < 0.001), and locomotion (P < 0.005) all increased with sleep deprivation, while ghrelin (P = 0.79) and leptin (P = 1.00) did not change with sleep deprivation. Using cross-correlation and multivariate modeling of these potential covariates along with homeostatic pressure (a measure of time awake/asleep), we found that time of day and homeostatic pressure together explained 44% of the variance in the hypocretin-1 data (P < 0.001), while cortisol did not significantly contribute to the overall hypocretin-1 variance. Locomotion during the daytime, but not during the nighttime, helped explain < 5% of the hypocretin-1 variance (P < 0.05). These data are consistent with earlier evidence indicating that in the squirrel monkey hypocretin-1 is mainly regulated by circadian inputs and homeostatic sleep pressure. Concomitants of wakefulness that affect hypocretin-1 in polyphasic species, such as locomotion, food intake, and food deprivation, likely have a more minor role in monophasic species, such as humans.     

A novel form of oxytocin in New World monkeys

Oxytocin is widely believed to be present and structurally identical in all placental mammals. Here, we report that multiple species of New World monkeys possess a novel form of oxytocin, [P8] oxytocin. This mutation arises from a substitution of a leucine to a proline in amino acid position 8. Further analysis of this mutation in Saimiri sciureus (squirrel monkey) indicates that [P8] oxytocin is transcribed and translated properly. This mutation is specific to oxytocin, as the peptide sequence for arginine vasopressin, a structurally related nonapeptide, is unaltered. These findings dispel the notion that all placental mammals possess a 'universal' oxytocin sequence, and highlight the need for research on the functional significance of this novel nonapeptide in New World monkeys.     

Split centromeric alpha-satellite FISH signals in a whole arm translocation 5p;10p: consequences and implications for interphase FISH studies

This is a case report of an apparently balanced whole arm translocation between the short arms of chromosomes 5 and 10 in which the centromeric alpha-satellite DNA is split between both derivative chromosomes for both probes, leading to abnormal signal patterns. The patient requested preimplantation genetic testing for the unbalanced products of the translocation. However, using centromeric alpha-satellite DNA probes as controls for the subtelomeric-specific probes in interphase was not informative because of the split signals. The ramifications of such variation in the alpha-satellite regions of chromosomes for other interphase FISH tests are discussed.