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J E Mazurkiewicz

Publications and source records attributed to J E Mazurkiewicz.

6 recordsLinked to original sources
PubMed1992

Transfection of murine P19S18 embryonal carcinoma cells with the oncogene neu induces an epithelioid phenotype.

An embryonal carcinoma cell line, P19S18, was transfected with the rat oncogene neu to investigate the function of its protein product, p185*, in a multipotential cellular environment. Levels of message for p185* were determined by in situ hybridization analysis and two highly expressing clones, PnnA and PnnB, were isolated. As demonstrated by indirect immunofluorescence and immunoprecipitation, these neu-transfected cells synthesized a full length rat p185*. The transfectants do not resemble typical embryonal carcinoma cells either before or after differentiation is induced by retinoic acid treatment. They are much larger, flatter, "epithelioid" cells. These cells have lost the expression of stage specific embryonic antigen-1 (SSEA-1), but do synthesize and assemble the basement membrane components laminin and fibronectin. These results suggest that expression of the neu oncogene in a multipotential cell line may induce the synthesis of proteins indicative of an epithelioid phenotype due to the presence of p185*.

Animals↗
PubMed1991

Ubiquitin deposits are present in spinal motor neurons in all stages of the disease in the motor neuron degeneration (Mnd) mutant of the mouse.

Monoclonal antibodies to ubiquitin were used in an immunocytochemical analysis of spinal cord from the Mnd (motor neuron degeneration) mouse, an animal model for motor neuron disease. Tissue from mice with mild, moderate and severe disease, from presymptomatic mice, and age-matched controls were analyzed. Ubiquitin deposits were observed in spinal neurons from presymptomatic animals and all stages of the disease. No immunoreactive deposits were observed in control mice at the concentration of the antibodies used. The presence of ubiquitin immunopositivity in presymptomatic spinal motor neurons suggests that ubiquitination might play a primary role in the pathogenesis of motor neuron disease in the Mnd mouse, and perhaps of motor neuron disease in general.

Animals↗
PubMed1979

A chemical mechanism for tissue staining by osmium tetroxide-ferrocyanide mixtures.

The presence of Fe(CN)6(-4) provides sequential, one-electron reduction pathways for OSO4. An equilibrium is established containing OSO4, Fe(CN)6(-4), Fe(CN)6(-3), OSO2(OH)4(-4), and labile cyano-bridged OS-Fe species containing Os in nominal oxidation states of VIII, VII, and VI. These osmium complexes are chelated by appropriately placed donor atoms in the macromolecular tissue matrix, and chelation facilitates the reduction of osmium in situ to lower oxidation states (predominantly IV) that are relatively nonlabile. The greater reactivity and concentration of the Os(VII and VI) intermediates in this system leads to more Os deposition than OsO4 alone; the chelation is responsible for the immobilization of Os and the observed staining pattern in electron micrographs. Chemical data from model systems and electron micrographs of tissue are presented in support of this mechanism.

Animals↗
PubMed1978

Cytochemical demonstration of sodium, potassium-adenosine triphosphatase by a hemepeptide derivative of ouabain.

A cytochemical probe for the ultrastructural localization of the NaKATPase was devised, which utilizes the biological affinity of the noncompetitive inhibitor, ouabain (ouab) to which was coupled a hemepeptide (H11P) which possesses peroxidatic activity. The conjugate, ouab-H11P, had an apparent Ki of approximately 8 x 10(-7) M. When reacted with fixed tissue from the salt gland of osmotically stressed ducklings, the NaKATPase was localized to the basal and lateral infoldings of the plasma membranes of secretory epithelial cells. Reaction product consisted of fine textured deposits distributed in focal patches on the outer aspects of the membrane. Apical membranes were negative, as were intracellular membrane components. Preincubation of tissue with unlabeled ouabain or binding of ouab-H11P in the presence of 10 mM K+, no ATP and no Mg++, resulted in the absence or diminution of reaction product.

Animals↗
PubMed1977

Cytochemical localization of acetylcholine receptors at the neuromuscular junction by means of horseradish peroxidase-labeled alpha-bungarotoxin.

The cytochemical localization of acetylcholine (ACh) receptors at the neuromuscular junction was investigated with a procedure utilizing alpha-bungarotoxin (alpha-BtX) labeled directly with horseradish peroxidase (HRP). Following incubation of tissues in the conjugate and reaction for peroxidase, activity was observed on the junctional folds of the motor endplate. A uniform layer of reaction product approximately 15 nm thick occurred over the apical portions of the junctional folds. Membranes at the bases of the synaptic cleft showed only small amounts of reaction product. Non-junctional regions of the muscle fiber were unreactive. Activity was also observed in the membrane of the axon facing the muscle surface, often including the axolemma overlying the "active zones" of the nerve terminal. Such presynaptic activity was still evident on nerve terminals disjuncted from the synapse by enzymatic treatment prior to incubation in the conjugate. This localization indicates the possible presence of presynaptic ACh receptors within the axolemma. In muscle denervated for 7-12 days, motor endplates were reactive and parajunctional sarcolemma showed slight activity, but most extrajunctional regions contained no obvious accumulations of reaction product. Activity at all sites was prevented by preincubation of tissues in native alpha-BTX prior to incubation in the conjugate and reaction for HRP. This procedure represents a simple and convenient method for the high resolution localization of ACh receptors.

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