Specialized structures on the border between rhizocephalan parasites and their host's nervous system reveal potential sites for host-parasite interactions.

Rhizocephalan barnacles are a unique group of endoparasitic crustaceans. In their extreme adaptation to endoparasitism, rhizocephalan adults have lost almost all features of their free-living relatives but acquired an outstanding degree of control over the body of their hosts (mostly decapods). The subtle influence exercised by rhizocephalans on the physiology, morphology and behaviour of their hosts is a vivid example of the most intimate host-parasite interactions but their mechanisms are very poorly known. In this study we examined the morphology and the adaptive ultrastructure of the organs invading the nervous system of the host in two rhizocephalan species from the families Peltogastridae, (Peltogaster paguri) and Peltogasterellidae (Peltogasterella gracilis). We found two essentially different types of structures involved in interactions of these two rhizocephalans with the nervous system of their hosts: modified rhizocephalan rootlets lying inside the ganglia and the neural fibres of the host enlacing the trophic rootlets of the parasites. We suggest that both these structures may be highly specialized tools allowing the parasite to interact with the host on the humoral level via neuromediators, hormones, attractants and trophic factors.

[Functional state of the adrenal cortex in patients with Parkinsonism before and after surgical treatment]. / Funktsional'noe sostoianie kory nadpochechnikov u bol'nykh parkinsonizmom do i posle khirurgicheskogo lecheniia

The results of biochemical examinations of the hormonal function of the adrenal cortex in 22 patients with Parkinson's disease are presented as seen prior and following stereotaxic operations on the ventro-lateral nucleus of the thalamus. It was found that parkinsonics have a decreased androgenic, glucocorticoid and mineralocorticoid function of the adrenal cortex. Long history and growing severity of the disease manifest themselves in a distinct inhibition of the adrenal cortex function. The importance of the changes in the functional state of the hypothalamo-hypophyseal system in the revealed disorders in the hormonal activity is emphasized. Along with a beneficial clinical effect surgery brings about an improvement of the functional state of the adrenal cortex.