A comparison of glycine, sarcosine, N,N-dimethylglycine, glycinebetaine and N-modified betaines as liposome cryoprotectants.

Glycinebetaine has previously been shown to be effective at reducing leakage from liposomes which are frozen then thawed. This study involved the preparation of a series of N-modified betaines and the comparison of their cryoprotective activities with those of glycine, sarcosine, N,N-dimethylglycine and glycinebetaine. All the compounds investigated, with the exception of (dimethyloctylammonio)acetate, reduced the degree of leakage, after freezing and thawing, with additive concentrations up to 0.6 M. Reducing the degree of N-terminal methylation of glycinebetaine appeared to increase the leakage from liposomes at additive concentrations between 0.2 and 0.6 M. (Dimethylethylammonio)acetate, (dimethylisopropylammonio)acetate and (N,N,N',N'-tetramethylethylenediammonio)-N,N'-diacetate appeared to be no more effective than glycinebetaine, whereas improved protection was afforded by (triethylammonio)acetate and (diethylmethylammonio)acetate at most concentrations. This study demonstrates that the cryoprotective activity of glycinebetaine may be improved with modifications to the N-terminal.     

Development of a Novel Scale to Assess Life Fulfilment as Part of the Further Refinement of a Quality-of-Life Model for Epilepsy

Summary: We have been involved in developing a health-related quality-of-life model for use as an outcome measure in epilepsy. As part of the further development of this model, we have developed a measure of life fulfilment. This scale is based on methods previously described by Krupinski in 1980. The value of Krupinski's approach is the opportunity for patients to weight the numerous aspects of their quality of life and assess the discrepancy between their actual and desired circumstances. The life fulfilment scale has been shown to be reliable (α= 0.7) and valid. The scale is currently being applied to several clinical studies in epilepsy. We believe that the scale provides a valuable contribution to our health-related quality-of-life model.     

A guide to upwardly mobile spermatozoa

Morphological comparison of sperm in raw ejaculates and swim-ups showed that the swim-up process does not simply increase the proportion of 'normal' sperm. Rather, sperm of specific morphologies have characteristic grades of upward motility.     

Reduction by delayed hypothermia of cerebral infarction following middle cerebral artery occlusion in the rat: a time-course study.

The effect of hypothermia on neuronal injury following permanent middle cerebral artery (MCA) occlusion in the rat was examined. Moderate hypothermia (body temperature 24 degrees C) was induced before MCA occlusion (0-minute delay group) in six rats, at 30 minutes in eight rats, and at 1 (seven rats), 2 (seven rats), and 3 (nine rats) hours after occlusion. The rats were kept at a 24 degrees C body temperature for 1 hour, then allowed to rewarm over 90 minutes. The animals were sacrificed 24 hours after MCA occlusion, and infarction was visualized by staining of coronal sections with 2,3,5-triphenyltetrazolium chloride. Infarct volumes were compared to matched normothermic control rats (body temperature 36 degrees C). Additional groups of 0-minute delay hypothermic (10 rats) and control animals (nine rats) were sacrificed 72 hours after MCA occlusion to examine the effects of prolonged survival. A significant reduction in the percentage of infarcted right hemisphere was seen in the animals sacrificed after 24 hours with 0-minute, 30-minute, and 1-hour delays in inducing hypothermia (mean +/- standard error of the mean: 2.2% +/- 0.7%, 4.4% +/- 0.9%, and 3.6% +/- 1.1%, respectively) as compared to normothermic control rats (10.8% +/- 1.5%, p less than 0.01 by Student's t-test). In the 2- and 3-hour delay groups, the percentage of infarcted right hemisphere was 17.1% +/- 2.4% and 12.0% +/- 2.7%, respectively, and no decrease in infarct volume was observed. The 0-minute delay hypothermia group sacrificed after 72 hours also displayed a significant reduction in right hemisphere infarct compared to their respective controls (4.8% vs. 11.7%, p less than 0.05). These findings indicate that, in the setting of permanent MCA occlusion, hypothermia markedly decreases brain injury even when its induction is delayed for up to 1 hour after the onset of ischemia. Ischemic damage does not appear to be merely retarded but permanently averted.     

Effect of 6-hydroxydopamine lesions of the amygdala on intravenous cocaine self-administration under a progressive ratio schedule of reinforcement

Bilateral six-hydroxydopamine (6-OHDA) lesions were placed in the amygdala of rats self-administering cocaine (1.5 mg/kg per injection i.v.) under a progressive ratio schedule of reinforcement. Post-lesion access to three doses of cocaine (1.5, 0.75 and 0.37 mg/kg per injection i.v.) revealed a lesion effect only at the highest dose. At this dose, the lesion caused a significant increase in breaking point. No change in the breaking point was produced at the lower two doses. The biochemical results show a significant reduction in dopamine and DOPAC levels within the amygdala and an increase in dopamine within the NACC. In contrast, noradrenaline and serotonin (5-HT) levels were unaffected by the lesion in any of the dissected areas. These results demonstrate that no specific effect on cocaine reinforcement was produced by 6-OHDA lesions of the amygdala. The possibility that the lesion may have attenuated the anxiogenic qualities of the high dose of cocaine is discussed.