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T K Roberts

Publications and source records attributed to T K Roberts.

66 records · Page 4Linked to original sources
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Muramyl peptides and the functions of sleep.

Muramyl peptides (MPs) are bacterially derived sleep factors which stimulate slow wave sleep. In the neonate, MPs are capable of inducing quiet sleep and suppressing active sleep. Given that active sleep is thought to be important for brain development during this period, the possibility that changes in the availability of MPs in the neonate may affect brain development was examined. Rat pups were given muramyl dipeptide (MDP) twice daily for the first 14 days post partum. It was hypothesised that MDP would stimulate quiet sleep at the expense of active sleep as has been shown in the young rabbit. There was no effect on neonatal levels of quiet sleep or active sleep. There was, however, a variety of effects, apparently unrelated to the sleep functions of MDP. These effects were changes in adult learning, serotonin metabolism and brain anatomy. The function of sleep in the mediation of the sleep-independent effects of MPs was examined, in particular the opposite effects of MDP on host immunity depending on the sleepiness of the host. In this light sleep does indeed serve to mediate the effects of MPs and it is speculated that many of the effects observed here may change in response to sleep levels in individuals. The notion that autonomic signalling between brain and spleen is more efficient during sleep is presented as an example of a function of sleep that may modulate the immunological effects of MPs.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMedDate not supplied

Anticomplementary activity in human semen and its possible importance in reproduction.

We demonstrated anticomplementary activity on once-washed human sperm, and in normal and vasectomized seminal plasmas. It was demonstrated to be a normal component of human semen. The origin of the activity is proposed to be the seminal plasma with sperm adsorption of activity. The properties of the seminal anticomplementary factor were characterized further, and the molecular size was shown to be less than 3500 daltons. Reduced anticomplementary activity was found to be associated significantly with abnormal semen profiles and infertility in males. The activity in seminal plasma was shown to have no effect on complement-dependent sperm immobilizing antibodies in the serum of an infertile woman, implicating an effect on the post-C3 components of the complement pathway. The inhibition of complement-dependent haemolysis and the lack of inhibition of complement-dependent sperm immobilization by the anticomplementary factor are considered in the implications of the role of seminal anticomplementary activity in reproduction.

Complement Inactivator Proteins↗