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Biomedical subjects

S Heinemann

Publications and source records attributed to S Heinemann.

At least 109 records · Page 6Linked to original sources
PubMed1977

Modulation of acetylcholine receptor by antibody against the receptor.

Antibody against acetylcholine receptor induces an increase in the rate of degradation of acetylcholine receptors on a mouse cell line (BC(3)H-1) and cultured rat skeletal muscle. The increased rate of degradation results in a lowered density of acetylcholine receptors on muscle membrane and a lowered sensitivity to iontophoretically applied acetylcholine. The modulation of acetylcholine receptor is energy, temperature, and time dependent and may be related to antigenic modulation found in other systems. Acetylcholine noise analysis demonstrates that antibody against acetylcholine receptor reduces the channel mean conductance and mean open time slightly. It is concluded that antibody binds to the acetylcholine receptor, impairs its function, and induces receptor degradation. This results in a lowered density of acetylcholine receptor and a lowered sensitivity to acetylcholine. Patients with myasthenia gravis have antibodies to their acetylcholine receptor in their serum. Antigenic modulation of receptor in the muscle of patients with myasthenia gravis could contribute to the observed decrease in amplitudes of miniature endplate potentials and in muscle acetylcholine sensitivity, and the symptoms of muscular weakness.

Acetylcholine↗
PubMed1976

Behavioral disorders in children with parental alcoholism.

The influence of parental alcoholism on the personalities of the children was studied by use of the Devereux Rating Scales to delineate problem behavior patterns. The subjects for the investigation were identified as a result of their parents being in treatment for alcoholism, and a control group matched for age, sex, race, family size, and socioeconomic status was utilized. The findings suggest that the presence of parental alcoholism acts as a serious deterrent to healthy personality development in the children, and the degree of disturbance in these individuals might be greater than previously suspected. Several implications of these observations are discussed, including the importance of considering alcohol abuse as a total family problem.

Adolescent↗
PubMed1975

Ultrastructural changes accompanying the induced differentiation of clonal rat nerve and glia.

Dibutyryladenosine 3'-5' monophosphate (DBcAMP) induces ultrastructural transformations in clonal rat nerve and glia. Cells cultured in the presence of DBcAMP contain large numbers of aligned microtubules and microfilaments in their elongated processes, while control cultures without DBcAMP are relatively devoid of these structures. In addition, the cells exposed to DBcAMP contain 2000 A to 6000 A vesicles which are not observed in control cells.

Animals↗
PubMed1974

Characterization of a unique muscle cell line.

A clonal cell line derived from a mouse neoplasm is described which shares many properties with smooth muscle. The cells have electrically excitable membranes capable of generating overshooting action potentials, and they contract both spontaneously and with electrical stimulation. They respond to the iontophoretic application of acetylcholine with a depolarizing response, and to norepinephrine with a hyperpolarizing response. Electron microscopy reveals that the cells have a morphology similar in many, but not all, respects to that of smooth muscle cells in vivo. The cells secrete soluble collagen-like molecules in addition to several proteins of undefined function. Finally, there is an increase in the specific activities of creatine phosphokinase and myokinase associated with increased cell density and the cessation of cell division.

Acetylcholine↗
PubMed1973

Nerve-muscle interaction in vitro. Role of acetylcholine.

Nerve and muscle cells from clonal lines interact in vitro, resulting in the association on the muscle surface of an area of increased acetylcholine sensitivity with a site of nerve-muscle contact. This localization of acetylcholine sensitivity on the muscle cell to a site of contact between nerve and muscle was found to occur when acetylcholine receptors on the muscle had been blocked with alpha-neurotoxin. Localization was also found to occur when the nerve cell had been prevented from releasing acetylcholine. It is concluded that neither the presence of active acetylcholine receptors on the muscle, nor the release of acetylcholine from the nerve, was required for the events leading to the localization of acetylcholine sensitivity in vitro.

Acetylcholine↗
PubMedDate not supplied

Identification of cultured cells expressing ligand-gated cationic channels.

We have identified cultured cells that express ligand-gated cation channels using a simple method which may also be applied to the screening of chemical agents for their use as agonists or antagonists. This assay is based upon the observation that many ligand-gated cation channels are permeable to lithium and agonists induce the flux of lithium into the cells which contain them. Since the accumulation of intracellular lithium can alter the cell cycle, the measurement of [3H]thymidine ([3H]thy) incorporation should reflect this occurrence. This expectation was realized using the PC12 cell line which expresses neuronal-like nicotinic acetylcholine receptor (nAChR). When cholinergic agonists are applied to PC12 cells in the presence of lithium-containing buffer and cells are subsequently pulsed with [3H]thy, the radiolabel incorporation into these cells relative to controls is reduced. If cholinergic antagonists are included or if the concentration of agonist either rapidly desensitizes receptors or is insufficient to induce channel opening, the reduction in [3H]thy incorporation is not observed. This method also provides a rapid way to screen cultured cell lines for those that express ligand-gated cation channels. This assay offers the potential to be automated for the low cost screening of drugs which act upon ligand-gated ion channels.

Animals↗