Zoltan Posalaky
University of Minnesota
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Featured researches published by Zoltan Posalaky.
Tissue & Cell | 1979
Dennis McGinley; Zoltan Posalaky; Martin Porvaznik; Lonnie D. Russell
Ultrastructural observations of rat seminiferous tubules show clearly the presence of plasma membrane junctions between Sertoli and germ cells in the basal and adluminal compartments. Results obtained from the freeze fracture and thin section techniques were correlated in order to elucidate the nature of these intercellular junctions. We suggest that these intercellular membrane specializations are gap junctions which occur within regions of plasma membrane that also exhibit adherens-like modifications.
Journal of Ultrastructure Research | 1977
Rita A. Meyer; Zoltan Posalaky; Dennis McGinley
Sertoli cells of the seminiferous tubules in immature rats (1–20 days) contain gap and tight junctions in different stages of development as identified in freeze-fracture replicas. Typical gap junctions and gap junction formation were observed between Sertoli cells. Tight junctions were observed to assume a variety of configurations including linear, macular, and extensive occluding complexes. Tight junction formation was also observed. A decrease in the frequency of gap junctions and a corresponding increase in the number of tight junctions was quantitatively shown.
British Journal of Dermatology | 1978
Harry Irving Katz; Zoltan Posalaky; Dennis McGinley
Benign appearing, multifocal, pigmented penile papules were found in three patients, showing the histopathological and electron microscopic changes of carcinoma in situ. Their clinical appearance, relation to other carcinoma in situ lesions, as well as possible pathogenesis are discussed.
Gastroenterology | 1986
Rita A. Meyer; Dennis McGinley; Zoltan Posalaky
The effects of aspirin on the canine gastric mucosal barrier were examined using the freeze-fracture and extracellular tracer techniques. Aspirin treatment (3, 20, or 40 min) resulted in alterations in tight junction complex morphology and permeability. Discontinuities in the apical occluding complex, hyperplastic tight junctions (extensions of the apical tight junction strands radiating over the lateral plasma membrane), and a variability in the number of strands (1-20) comprising the complex were observed. A concurrent increase in lanthanum permeability between nonnecrotic surface mucous epithelial cells was also demonstrated. The results of these experiments may suggest that aspirin-induced impairment of the tight junction complexes between viable gastric mucosal epithelial cells may be a major contributing factor in the etiology of stomach disorders.
The Journal of Steroid Biochemistry and Molecular Biology | 2002
Charles H. Blomquist; Martin Bonenfant; Dennis M McGinley; Zoltan Posalaky; David J. Lakatua; Sarah Tuli-Puri; Dennis G. Bealka; Yves Tremblay
17beta-Hydroxysteroid dehydrogenase/17-ketosteroid reductases (17HSD/KSR) play a key role in regulating steroid receptor occupancy in normal tissues and tumors. Although 17HSD/KSR activity has been detected in ovarian epithelial tumors, our understanding of which isoforms are present and their potential for steroid metabolism is limited. In this investigation, 17HSD/KSR activity from a series of ovarian epithelial tumors was assayed in cytosol and microsomes under conditions which differentiate between isoforms. Inhibition studies were used to further characterize the steroid specificities of isoforms in the two subcellular fractions. Activity varied widely between tumors of the same histopathologic classification. The highest levels of activity were observed in mucinous tumors. Michaelis constants, maximum velocities, estradiol-17beta/testosterone (E(2)/T) activity ratios and inhibition patterns were consistent with a predominance of microsomal 17HSD/KSR2 and cytosolic 17HSD/KSR5, isoforms reactive with both E(2) and T, with evidence of estrogenic 17HSD/KSR1 in cytosol from some samples. In tumors where activity and mRNA expression were both characterized, Northern blots, PCR and sequence analysis indicated 17HSD/KSR5 was the predominant isoform. The presence of 17HSD/KSR5, which also has both 3alpha-HSD/KSR and 20alphaHSD/KSR activity, and 17HSD/KSR2 which also has 20alpha-HSD activity, could influence not only estrogen and androgen binding but progesterone receptor occupancy, as well, in receptor-containing tumors.
Arthroscopy | 1990
Jack M. Bert; Zoltan Posalaky; Stephen J. Snyder; Dennis McGinley; Cay Chock
The effect of five different irrigating fluids on the ultrastructure of articular cartilage was studied utilizing the scanning electron microscope. Gross histologic studies have shown no significant difference amongst commonly used irrigating fluids on the surface or matrix composition of articular cartilage. Recent in vivo and in vitro biochemical studies, in addition, have shown no significant deleterious effects of irrigating fluids on articular cartilage composition. This study was prospectively undertaken to assess the effect of irrigating fluids on the ultrastructure of articular cartilage. When comparing five irrigating solutions utilizing the scanning electron microscope, specimens irrigated with 1.5% glycine seemed to show a more consistently smooth appearance. Ultrastructural changes were noted with the other four irrigating solutions tested.
Journal of Ultrastructure Research | 1984
Rita A. Meyer; Dennis McGinley; Zoltan Posalaky
The canine gastric mucosa consists of two regions, the surface mucous cells and gland area cells including parietal, chief, and mucous-containing cells. We have used quantitative freeze-fracture methods in conjunction with thin-section extracellular tracers to document and correlate tight junction morphology with epithelial permeability. The number of strands in the tight junction complexes of the surface cells and gland cells is the same, but differences in strand arrangement exist. The surface cells have an interwoven tight junction configuration which is impermeable to extracellular tracers. The gland cell junctions are regularly arranged and often permeable to extracellular lanthanum. The possibility that the observed difference in permeability between the tight junctions of the surface mucous cells and those of the gland cells is related to their structural configuration is discussed.
Journal of Cutaneous Pathology | 1980
Bruce Cutler; Zoltan Posalaky; H. Irving Katz
Three cell process types are described in basal cell carcinoma. The most abundant are thin processes resembling microvilli; thick processes, mesa‐like structures often surmounted by desmosomes; and large bulging processes. Processes occur in the intercellular spaces, and are more numerous in spinocellular cells than in basaloid cells. Despite the abundance of processes in basal cell carcinoma, they do not usually penetrate the basal lamina border of the tumor. This behavior differs from more rapidly invasive squamous cell carcinoma where processes extend through the fragmenting basal lamina into the stroma.
Virchows Archiv | 1979
Zoltan Posalaky; Dennis McGinley; Bruce Cutler; H. Irving Katz
Intercellular junctions of various types were found on the membrane fracture faces of human nodular basal cell carcinoma (BCC) cells. The junctional types represented include desmosomes, tight junctions, and gap junctions. A semiquantitative comparison of undifferentiated and differentiated nodular BCC showed that gap and tight junctions were observed on all exposed membrane fracture interfaces of the differentiated tumors, while only fifty six per cent of the membrane interfaces of the undifferentiated tumor exhibited similar junctional specializations. These membrane specializations may be a partial reflection of differentiation among the different types of BCC and their contribution to the less invasive character of nodular BCC cannot be ruled out.
Virchows Archiv | 1989
Zoltan Posalaky; Irene Posalaky; Dennis McGinley; Rita A. Meyer
Tight junctions of the human gastric mucosa were examined using quantative freeze-fracture methods. Biopsies examined were from patients with gastric diseases including gastritis, ulcers, and pernicious anemia. No significant differences were seen in strand number or tight junction complex depth among the biopsies analyzed, however, anomalous tight junction structures were observed. Discontinuities in the tight junction complex and hyperplastic tight junctions (extensions of the apical tight junction strands radiating over the lateral plasma membrane) were seen. These alterations were not associated exclusively with either the diagnosis of gastritis or ulcers. However, a higher frequency of tight junction breaks was seen in stomach biopsies diagnosed as gastritis while those diagnosed as ulcers displayed a higher occurrence of hyperplastic tight junctions.