Effect of melatonin-rich night-time milk on sleep and activity in elderly institutionalized subjects.

Melatonin production decreases with advancing age, leading to insomnia and changes in circadian rhythmicity. Administration of melatonin in variable doses resulting in supraphysiological or physiological night-time blood levels of melatonin has been shown to improve sleep quality in the elderly. To study the effect of low doses of melatonin, which do not affect daytime blood melatonin concentrations, night-time milk containing 10-40 ng/l melatonin was used as a drink with meals. The effect of about 0.5 l night-time milk daily on sleep quality and circadian activity was studied in elderly institutionalized subjects in two long-term double-blind, placebo-controlled, crossover studies. Night-time milk was given for 8 weeks and normal day-time milk for 8 weeks with a 1-week washout period in between. In the first study, which was performed during spring with sleep quality evaluated subjectively by specially trained nurses, 70 demented patients showed only a seasonal effect on their sleep quality. In the second study performed around the winter solstice, 81 fairly healthy subjects living in rest-homes were divided into three groups, two for the crossover study as in the first investigation with a third group consuming only normal daytime milk as a control group to evaluate the effect of season. Caregivers graded the sleep quality and activity that was monitored separately for the morning before noon and for the evening after noon. In the second study, the effect of season was recognizable in the scores for sleep quality, which increased in all groups after the winter solstice. However, there were no changes in activity in the control group or in the group that consumed night-time milk during the first period of the crossover study, whereas both morning and evening activity increased significantly in the group that consumed night-time milk during the later period. Even ultra-low doses of melatonin may benefit the elderly by increasing their daytime activity.

Transfer of European mink (Mustela lutreola) embryos into hybrid recipients.

The European mink is considered as a highly endangered Mustelidae species. The objective of this study was to explore the intriguing possibility of embryo transfer from European mink to closely related Mustelidae recipient females. To overcome interspecies pregnancy failure, embryos of European mink (Mustela lutreola) were transferred into hybrid females obtained after mating of European polecat (Mustela putorius) males and European mink (M. lutreola) females and vice versa. A total of 32 blastocysts were surgically flushed from the uteri of nine European mink donors and surgically transferred into six pseudopregnant hybrid recipients. One of the recipients received a single embryo and did not whelp. The remaining five recipients each received five to eight embryos and delivered kits. The overall success rate was 50% (16 kits/32 transferred embryos). For both male and female offspring, the average birth weight was lower in ET group when compared with naturally bred control population of European mink. The postnatal mortality rate was significantly higher in ET group as compared to controls: only 9 of 16 kits survived past the first week. At 10 days of age, the average weight for male offspring from the ET and control groups did not differ, although differences still persisted at this age for female offspring. At 3 months of age, the weight of male and female offspring in the ET group did not differ from European minks born after natural mating. We propose that transfer of European mink embryos to hybrid recipients be considered as a new experimental tool within the framework of ex situ approach conservation of this aboriginal European mustelid.

Surgical recovery and successful surgical transfer of conventionally frozen-thawed embryos in the farmed European polecat (Mustela putorius).

Surgical transfer of in vivo produced conventionally frozen-thawed embryos of farmed European polecat (Mustela putorius) was investigated as a part of an ex-situ preservation program which has the long-term aim of developing a genome resource bank for the endangered European mink (Mustela lutreola). Eighteen oestrous yearling European polecat donors were mated once daily on two consecutive days using 13 fertile males. The donors were surgically flushed for embryos 8-9 days after the first mating. The embryo recovery rate was 60% (116 embryos/193 corpora lutea). The embryos were cryopreserved with 1.5 M ethylene glycol in a programmable freezer using a conventional slow freezing protocol. The thawed embryos were surgically transferred either after dilution with 0.5 M sucrose or directly without removal of ethylene glycol. To induce ovulation, eight recipient females were mated once daily on two consecutive days with vasectomized males starting 7 or 8 days before embryo transfer. The recipients received 7-11 embryos each and three recipients delivered a total of nine pups after a gestation length of 44-46 days. The embryo survival rate was 10% (9 pups/93 frozen embryos). This report describes the first successful cryopreservation of embryos in the Mustelidae family resulting in viable offspring. The low embryo survival rate, however, indicates that the freezing-thawing protocol needs to be improved.

Surgical transfer of in vivo produced farmed European polecat (Mustela putorius) embryos.

Surgical embryo transfer of farmed European polecat (Mustela putorius) was investigated as part of an ex situ preservation project. The long-term objective of the project is to develop effective technology for ex situ conservation of the European mink (Mustela lutreola), which is a highly endangered aboriginal European species. Twenty European polecat females, which served as a model species for the European mink, were humanely killed 4-9 days after first mating and embryos were recovered from oviducts and uteri. Donor-recipient pairs (n = 16) were generated by mating the donors (n = 20) once a day for 2 consecutive days with fertile males and by mating the corresponding recipients (n = 16) on the same days with vasectomized males. An embryo recovery rate of 70% (200 recovered embryos/284 corpora lutea) was achieved from 20 donors. Morulae and blastocysts were recovered between Days 5 and 9 after first mating and were regarded as the best developmental stages for uterine embryo transfer. A total of 172 embryos were transferred surgically under general anaesthesia into the ovarian third of the left uterine horn of 16 recipients with a thin glass capillary. Eleven recipients (69%) produced 72 pups equivalent to an average success rate of 42% (72 pups/172 transferred embryos). The average litter size was 4.5 (range 0-9). These results with this model species, farmed European polecat, demonstrate the potential of embryo transfer as an effective method for the preservation of the endangered European mink (M. lutreola). These species are closely related and have a similar reproductive physiology. However, success of applying embryo transfer in conserving European mink is still dependent on further studies both into its reproductive physiology and developing of improved flushing techniques for anaesthetized donors and the successful transfer of frozen-thawed embryos.