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Biomedical subjects

S Tyler

Publications and source records attributed to S Tyler.

23 records · Page 2Linked to original sources
PubMed1979

Distinctive features of cilia in metazoans and their significance for systematics.

A comparative study of epidermal cilia in the Turbellaria and Nemertea has revealed features in these organelles that are specific to certain taxonomic groups. Turbellarians of the order Acoela, in particular, have a characteristic pattern of axonemal filament termination in the distal tips of their cilia and a characteristic ciliary rootlet system that is not seen in other turbellarian orders nor in other metazoans. Each epidermal cilium in acoels has a typical 9 + 2 axonemal pattern through the main part of its length, but near its distal tip there is an abrupt shelf-life narrowing at which filaments 4-7 terminate; filaments 1, 2, 8 and 9 continue into the thinner distal-most part of the shaft along with singlet microtubules from the axonemal center. The rootlet system in acoel cilia involves an interconnecting pattern with lateral connectives. The unique structure of these cilia has systematic and phylogenetic significance for the Acoela, and it is argued that ultrastructural characters in general, including characters of organelles, can be validly applied to the phylogeny and systematics of the Metazoa.

Animals↗
PubMed1975

Uniflagellate spermatozoa in Nemertoderma (Turbellaria) and their phylogenetic significance.

An ultrastructural study of Nemertoderma (Turbellaria, Nemertodermatida) has revealed that its spermatozoa have only a single falgellum. This is the first uniflagellate spermatozoon known in the Turbellaria; it is indicative of the primitiveness of Nemertoderma and is evidence in support of the view that the Turbellaria as a whole are among the most primitive living Bilateria.

Acrosome↗
PubMedDate not supplied

Interleukin-4 (B-cell stimulatory factor-1) augments the in vivo generation of cytotoxic cells in immunosuppressed animals.

Thymus-derived lymphocytes (T cells) are thought to play an important role in the recognition and destruction of neoplastic cells in the host. This principle has provided a foundation for the establishment of therapy with T-cell-stimulating lymphokines, notably interleukin-2, as an approach to the eradication of certain malignancies. Another lymphokine, B-cell-stimulatory factor-1 (BSF-1), also known as IL-4, has also been shown to be capable of inducing T-cell proliferation and cytolytic activity in vitro. We demonstrate herein that in immunosuppressed mice, in vivo IL-4 administration enhances the ability of treated animals to generate cytotoxic T lymphocytes directed against an allogeneic tumor challenge. Moreover, IL-4 is approximately 25 times more effective, on a weight basis, than is IL-2 in augmenting cytotoxic T-lymphocyte activity. This difference in efficiency between the two lymphokines may be partly due to the in vivo half-life. We have found that IL-4 has a serum half-life of 19 +/- 2 min following intravenous administration, in contrast to the half-life of IL-2, which has been reported to be 3.7 min +/- 0.8. These results are not only of interest for our basic understanding of the physiological role of IL-4 but may have immediate importance in clinical settings where lymphokine therapy is contemplated.

Animals↗