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C F Lagenaur

Publications and source records attributed to C F Lagenaur.

24 records · Page 2Linked to original sources
PubMed1989

Reactive disulfides trigger Ca2+ release from sarcoplasmic reticulum via an oxidation reaction.

Reactive disulfide compounds (RDSs) with a pyridyl ring adjacent to the S-S bond such as 2,2'-dithiodipyridine (2,2'-DTDP), 4,4'-dithiodipyridine, and N-succinimidyl 3(2-pyridyldithio)propionate (SPDP) trigger Ca2+ release from sarcoplasmic reticulum (SR) vesicles. They are known to specifically oxidize free SH sites via a thiol-disulfide exchange reaction with the stoichiometric production of thiopyridone. Thus, the formation of a mixed S-S bond between an accessible SH site on an SR protein and a RDS causes large increases in SR Ca2+ permeability. Reducing agents, glutathione (GSH) or dithiothreitol reverse the effect of RDSs and permit rapid re-uptake of Ca2+ by the Ca2+, Mg2+-ATPase. The RDSs, 2,2'-DTDP, 4,4'-dithiodipyridine and SPDP displaced [3H]ryanodine binding to the Ca2+-receptor complex at IC50 values of 7.5 +/- 0.2, 1.5 +/- 0.1, and 15.4 +/- 0.1 microM, respectively. RDSs did not alter the rapid initial phase of Ca2+ uptake by the pump, stimulated ATPase activity, and induced release from passively loaded vesicles with nonactivated pumps; thus they act at a Ca2+ release channel and not at the Ca2+, Mg2+-ATPase. Efflux rates increased in 0.25-1.0 mM [Mg2+]free then decreased in 2-5 mM [Mg2+]free. Adenine nucleotides inhibited the oxidation of SHs on SR protein by RDSs and thus reduced Ca2+ efflux rates. However, once RDSs oxidized these SH sites and opened the Ca2+ release pathway, subsequent additions of nucleotides stimulated Ca2+ efflux. In skinned fibers, 2,2'-dithiodipyridine elicited rapid twitches which were blocked by ruthenium red. These results indicate that RDSs trigger Ca2+ release from SR by oxidizing a critical SH group, and thus provide a method to covalently label the protein(s) involved in causing these changes in Ca2+ permeability.

Adenosine Triphosphatases↗
PubMed1989

Characterization of primary cell cultures derived from rat renal proximal tubules.

Proximal tubules were prepared from rat kidney cortex by collagenase digestion and purified by Percoll gradient centrifugation. Their enrichment was estimated by comparing the specific activities of various cell-specific enzymes in homogenates of renal cortex and of the isolated tubules. The tubules were cultured in a 50:50 mixture of Dulbecco's modified Eagle's and Ham's F12 media supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, and prostaglandin E1. After 2 to 3 d an extensive outgrowth of epithelial cells developed from the attached tubules. After 5 to 7 d near confluent monolayers were obtained. Hormonal responsiveness, marker enzyme activities, and transport properties were determined to further characterize the primary cultures. The cultured cells exhibited increased cyclic AMP production in response to parathyroid hormone but not calcitonin or vasopressin, consistent with the absence of cells derived from distal and collecting tubules. The cells also retained significant levels of 25-hydroxyvitamin D3-1 alpha-hydroxylase, alkaline phosphatase, and gamma-glytamyl-transpeptidase, three enzymes that are primarily associated with the proximal tubule. The cultured epithelial cells also exhibit a Na+-dependent phosphate and glucose transport systems. Therefore, the cells retain many functional properties that are characteristic of proximal tubules. Thus, the primary cultures should be suitable for the study of processes that occur specifically within this segment of the rat nephron.

Animals↗
PubMed1987

A new marker for identifying quail cells in embryonic avian chimeras: a quail-specific antiserum.

The characterization of cell behavior in quail chick chimeras has greatly increased our knowledge of the ontogeny of embryonic cell populations and the role of cell-cell interactions in development. We sought to extend the value of avian chimeras by producing a marker that would recognize cell surface components and that could be used instead of the traditional nuclear marker to identify quail cells within chimeras. We describe here a quail-specific antiserum produced by injecting chickens with a membrane fraction of 6-10-day quail embryos. By use of peroxidase coupling of a second antibody, serum reactivity was tested in tissue sections of normal quail and chick embryos and of somitic mesoderm and neural tube chimeras. The primary time period examined was 6-10 days of development. At these stages, the antiserum recognizes only quail cells and stains both plasma membrane-associated and cytoplasmic cell components. The latter characteristics allow the identification of quail axons in chimeras and facilitate visualization of quail cells at low magnification. We show that antiserum staining can also be used to identify quail cells in culture and can be combined with orthograde HRP labeling of neurons.

Animals↗
PubMed1986

Cell surface changes in the developing optic nerve of mice.

A recently defined antibody to a cell surface protein, M6, inhibits neurite outgrowth in culture (Lagenaur, Fushiki, and Schachner: Soc. Neurosci. Abstr. 10:739, '84). In the developing mouse, the antibody stains all parts of the primary optic pathway at birth. Over the next week, staining is lost from the proximal segment of the optic nerve and a week later from the more central part of the nerve. By contrast staining persists through adulthood in the optic fiber layer of the retina. This means that single axons in the mature optic nerve express the antigen over only the proximal few millimeters of their course and over their terminal region. The results are discussed in relation to the overall maturation of the optic pathway and to the processes of membrane maturation and myelination.

Animals↗
PubMed1985

Use of a species-specific antibody for demonstrating mouse neurons transplanted to rat brains.

A cell surface monoclonal antibody specific for mouse central nervous system neurons was used to identify mouse tissue transplanted to neonatal rat brains. Neuronal cell bodies and processes were stained in the transplants. Immature axons were stained growing out of the transplants into the host brain; and in mature brains unmyelinated axons and terminal plexuses were demonstrated. The technique allows a variety of studies to be performed on transplant-host interactions, especially in circumstances where the two are closely apposed.

Animals↗