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Biomedical subjects

J Koenig

Publications and source records attributed to J Koenig.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

A rapid method of freezing biopsied muscle: in vitro study development.

This work compares the efficacy of varying the concentrations of cryoprotectants when freezing samples of rat muscles for later use in tissue culture. The best yields were obtained with DMSO associated with glycerol and sucrose; before plating, the best results indicated 45% of cells with respect to controls, and delayed (24-36 h) myotube maturation. Maturation was studied by analysing the molecular forms of acetylcholinesterase and the ability of myotubes to form synapses in the presence of neurons, in fresh and frozen muscle.

Acetylcholinesterase↗
PubMedDate not supplied

The Schwann cell at the neuromuscular junction.

Synapses obtained in vitro in a system of co-culture of muscle cells and neurons are of embryonic type. We prepared a monoclonal antibody (6.17) which recognizes a molecule synthesized by Schwann cells and used it to show that the main characteristics of maturity (decrease in number of synapses, appearance of junctional folds, and suppression of butyrylcholinesterase expression) are under the control of Schwann cells. In addition, Schwann cells have the capacity to aggregate the acetylcholine receptors in myotube cultures.

Animals↗
PubMedDate not supplied

Potential interference of cyclobenzaprine and norcyclobenzaprine with HPLC measurement of amitriptyline and nortriptyline: resolution by GC-MS analysis.

Cyclobenzaprine and its major metabolite, norcyclobenzaprine, differ from amitriptyline and nortriptyline only by the presence of a double bond in the cycloheptane ring. Three patients developed sufficient levels of cyclobenzaprine and norcyclobenzaprine because of either rapid or long-term ingestion of cyclobenzaprine to cause positive interferences in both a Syva EMIT assay and a high-performance liquid chromatographic (HPLC) assay for identification and quantitation of tricyclic antidepressants in serum. Cyclobenzaprine coeluted with amitriptyline, and norcyclobenzaprine eluted slightly earlier than, but was poorly resolved from, nortriptyline in this HPLC assay. We found that cyclobenzaprine could be distinguished from amitriptyline and that norcyclobenzaprine could be distinguished from nortriptyline on the basis of gas chromatographic retention times upon gas chromatographic-mass spectrometric analyses after derivatization with trifluoroacetic anhydride. The compounds were also distinguishable by mass spectrometric criteria.

Acetic Anhydrides↗
PubMedDate not supplied

The respiratory effects of volatile organic compounds.

Volatile organic compounds (VOCs) have been implicated as causative agents in asthma and building-related illness. To determine whether a mixture of VOCs could impair lung function or cause airway inflammation among subjects without bronchial hyperresponsiveness, the authors conducted a randomized, crossover-design trial of controlled human exposures to filtered air for four hours, VOCs at 25 mg/m(3) for four hours, and VOCs at 50 mg/m(3) for four hours, using a VOC mixture based on sampling of indoor environments. VOC exposures caused dose-related increases in lower respiratory, upper respiratory, and non-respiratory symptoms, with no significant change in lung function (FEV(1);, FVC, or FEF(25-75), nasal lavage cellularity or differential cell counts, induced sputum cellularity or differential cell counts, or biomarkers of airway inflammation, including IL-8, LTB(4), or albumin in nasal lavage or induced sputum samples. Atopic individuals had significantly reduced FEE(25-75 following exposure to VOCs at 50 mg/m(3), suggesting that these individuals may be more sensitive to the health effects of VOCs. The authors conclude that reductions in levels of VOCs to substantially less than 25 mg/m(3) are required if a "non-irritating" work environment is desired.

Adult↗