Biomedical subjects

M G Rittig

Publications and source records attributed to M G Rittig.

21 records · Page 2Linked to original sources

PubMed1993

Innervation of the ciliary process vasculature and epithelium by nerve fibers containing catecholamines and neuropeptide Y.

The ciliary processes (CPs) in the rat were investigated for the presence of neuropeptide Y (NPY)-like immunoreactivity and for histofluorescence indicating catecholamine (CAM)-ergic innervation in the rat, rabbit and cynomolgus monkey. Special attention was paid to those CP vessel segments which in previous studies showed distinct reactions on application of CAM or NPY, and on the respective sections of the CP epithelium. In the rat and cynomolgus monkey most CAM-ergic nerve fibers concentrated along the terminal arterioles and the epithelium of the anteriormost portion of the major CPs. In comparison, the rabbit displayed most intense CAM-ergic innervation along the terminal arterioles and the epithelium of both the iridial processes and the anterior portion of the major CPs. The NPY-ergic nerve fibers built up a dense subepithelial nervous plexus in the anterior portion of the rat CPs, diminishing towards the posterior CPs. Also, many NPY-ergic fibers were found along the terminal arterioles of the anterior CPs. The findings demonstrate that CAM- and NPY-ergic nerve fibers preferentially supply vasculature and epithelium of the anterior ciliary processes, suggesting a crucial function of these structures for the precise regulation of aqueous humor formation.

Animals↗

PubMed1992

Coiling phagocytosis is the preferential phagocytic mechanism for Borrelia burgdorferi.

The uptake mechanism for the spirochete Borrelia burgdorferi, the causative agent of Lyme disease, was investigated by electron microscopy for human and murine phagocytes. Spirochetes of both a low- and a high-passage strain were preferentially internalized by coiling rather than by conventional phagocytosis. The spirochetes engulfed by coiling phagocytosis were found to disintegrate in an organelle exclusion zone without evident participation of lysosomes. Preincubation of B. burgdorferi with monoclonal antibody to the spirochetal OspA enhanced phagocytosis in general but did not consistently influence the uptake mechanism. Quantitative and kinetic differences concerning the phagocytic rate and mechanism were evident between cells from different lineages, different human individuals, and mice and humans. In general, when few phagocytes participated in spirochete uptake, the active cells displayed a high ratio of coiling versus conventional phagocytosis. These results suggest that coiling phagocytosis of B. burgdorferi plays a critical role in the control of spirochetal infection. More detailed studies on the molecular basis of this phagocytic mechanism may lead to new insights into the pathogenesis of Lyme borreliosis, a disease which is frequently characterized by the host's inability to eliminate the pathogenic spirochete.

Adult↗

PubMedDate not supplied

Phagocytes from both vertebrate and invertebrate species use "coiling" phagocytosis.

Coiling phagocytosis has been observed previously only by chance, and there has been no systematic investigation of this uptake mechanism. Therefore, a comparative electron microscopical study was performed. Different human and murine cell populations, phagocytes from various vertebrate and invertebrate species, and predatory amoebae were incubated with Borrelia burgdorferi, one of the microbes known to induce coiling phagocytosis, to study the uptake mechanisms used. In this model, coiling phagocytosis was observed with both vertebrate and invertebrate species but not with amoebae. With cells from humans and mice, this uptake mechanism was restricted to phagocytic cells of myeloid origin. The coiled membrane gaps did not give rise to phagosomes; instead, membrane fusion was followed by membrane dissipation. Thus, coiling of B. burgdorferi apparently is an alternative uptake mechanism used by metazoan phagocytes, involving special membrane processing. However, coiling phagocytosis may show different features with different microbes.

Animals↗