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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure and cytochemical staining characteristics of canine natural killer cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 243 (1995), S. 509-515 
    Details
    ISSN: 0003-276X
    Keywords: NK cell ; Dog ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The purpose of this work was to describe the ultrastructure and cytochemical staining characteristics of canine peripheral blood lymphocytes with natural killer (NK) cell activity, with comparison made to non-NK lymphocytes.Methods: Canine lymphocyte populations evaluated for ultrastructure, cytochemical staining, and NK function (by 51 chromium release assay) included: peripheral blood lymphocytes; lymphocytes from band 1 (NK-enriched), band 2, and the pellet of a 45/50% percoll gradient; lymphocytes from the supernatant fluid (non-conjugated lymphocytes) and pellet (lymphocytes conjugated to tumor cell targets) of a 17% percoll gradient; and null (CD4-CD8-) and CD4-CD8+ lymphocytes.Results: NK activity was concentrated in band 1 lymphocytes of the 45/50% percoll gradient with further enhancement of activity occurring in sorted null cells. Canine NK cells were 5.5 to 6.5 μm in diameter with a reniform (kidney bean shape) nucleus, and electron-dense cytoplasmic granules. NK cells (percoll band 1 cells and null cells) had larger cell and nuclear area, and less round nuclei when compared to non-NK lymphocytes. The overall cytochemical staining (chloracetate esterase, peroxidase, sudan black B, naphthyl acetate esterase, naphthyl butyrate esterase periodic acid-Schiff stain, and acid phosphatase with and without tartrate) pattern was similar in all the lymphocyte populations evaluated.Conclusions: This work confirms the usefulness of a 45/50% percoll gradient in obtaining a NK-enriched fraction of canine lymphocytes, and shows further enhancement of NK activity in sorted CD4-CD8- cells. The ultrastructure of canine NK cells is similar to that reported for human NK cells, but is different from that of other canine peripheral blood lymphocytes. Standard cytochemical staining does not discriminate canine NK cells from other lymphocytes. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092430413
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  • 2
    Electronic Resource
    Electronic Resource
    Strategy and planning for chemopreventive drug development: Clinical development plans (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 55-62 
    Details
    ISSN: 0730-2312
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: At the National Cancer Institute, Division of Cancer Prevention and Control, the Chemoprevention Branch and Agent Development Committee develop strategies for efficiently identifying, procuring, and advancing the most promising drugs into clinical trials. Scientific expertise is applied at each phase of development to critically review the testing methods and results, and to establish and apply criteria for evaluating the agents for further development. The Clinical Development Plan, prepared by the Chemoprevention Branch and the Agent Development Committee, is a summary of the status of the agent regarding evidence for safety and chemopreventive efficacy in preclinical and clinical studies. It also contains the strategy for further development of the drug that addresses pharmacodynamics, drug effect measurements, intermediate biomarkers for monitoring efficacy, toxicity, supply and formulation, regulatory approval, and proposed clinical trials. Sixteen Clinical Development Plans are presented here: N-acetyl-l-cysteine (NAC), aspirin, calcium, β-carotene, 2-difluoromethylornithine (DFMO), DHEA analog 8354, 18β-glycyrrhetinic acid, N-(4-hydroxyphenyl)retinamide (4-HPR), ibuprofen, oltipraz, piroxicam, Proscar®, sulindac, tamoxifen, vitamin D3 and analogs and vitamin E. The objective of publishing these plans is to stimulate interest and thinking among the scientific community on the prospects for developing chemopreventive drugs. 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240560906
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  • 3
    Electronic Resource
    Electronic Resource
    Region-specific patterns of beta keratin expression during avian skin development (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 196 (1993), S. 283-290 
    Details
    ISSN: 1058-8388
    Keywords: “Scaleless” mutation ; Cell adhesion molecules ; Integument ; Developing chicken skin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The transient embryonic layers primarily composed of a periderm and subperiderm cover most regions of the chick embryo and are the first suprabasal cell layers covering the body ectoderm. This study presents evidence for regional vriation in the expression of beta keratin in the embryonic layers. Here we show that the embryonic layers covering the anterior metatarsal region of the chicken hindlimb (scutate scale forming region) produce several members of the beta keratin family of polypeptides, designated beta (β) 1-7. These specific polypeptides are later expressed in this region exclusively in the thick, cornified beta strata of mature scutate scales. In contrast to this sequence of events, the embryonic layers overlying the epidermis of the ventral foot pad (reticulate scale-forming region) and those covering the epidermis in apteric regions of the body produce beta keratin polypeptides β1-3 and β2,3, respectively, but no subsequent expression of these proteins occurs in the mature epidermises of these regions. Furthermore, we find that the embryonic layers of the skin overlying the anterior metatasal region of birds homozygous for the mutation “scaleless” (sc/sc), which completely lack scutate scales, produce the same members of the beta keratin family, β1-7, as the embryonic layers and beta strata of normal scutate scales.Thus, the accumulation of specific beta keratin polypeptides in the developing anterior metatarsal region appears to occur in two distinct phases; first, an early region-specific expression in cells of the embryonic layers followed by a second phase of expression which occurs in conjunction with appendage morphogenesis. The relationship between differentiation of embryonic skin and the expression of beta keratins is discussed. © 1993 wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001960411
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  • 4
    Electronic Resource
    Electronic Resource
    Structural characteristics of two highly selective opioid peptides (1989)
    New York, NY : Wiley-Blackwell
    BioEssays 10 (1989), S. 58-61 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The demonstration of opioid receptors by radioligand binding and the discovery of their endogenous peptide ligands has provided a new class of compounds that can be used for the development of novel opioids. The number of potential receptor targets for such opioids has been expanded by the identification of multiple opioid receptor types The development of highly selective opioid peptides using the principles of conformational restriction permits the analysis of the structure-activity requirements of each receptor type, and is facilitating the elucidation of the functional properties of the different opioid receptors.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950100206
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  • 5
    Electronic Resource
    Electronic Resource
    Transforming growth factor-β1 localization in normal and psoriatic epidermal keratinocytes in situ (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 144 (1990), S. 144-150 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transforming growth factor-β1 (TGFβ1) is a potent inhibitor of epithelial cell proliferation and its effects on growth and differentiation have been extensively characterized in cultured keratinocytes. We used two TGFβ1-specific polyclonal antibodies (anti-LC and anti-CC) to determine the presence of TGFβ1 peptide in keratinocytes in sections of normal human skin in situ and in both plaque and nonplaque skin from individuals with psoriasis. In contrast to the differentiation phenotype expressed by keratinocytes in normal epidermis, keratinocytes in the psoriatic plaque exhibit a hyperproliferative/regenerative differentiation phenotype. Anti-TGFβ1 staining was observed primarily in the epidermis. Anti-LC TGFβ1 antibody stained nonproliferating, differentiated suprabasal keratinocytes intracellularly in normal skin but did not stain psoriatic plaques from five of seven patients. In contrast, anti-CC TGFβ1 antibody stained suprabasal keratinocytes extracellularly in psoriatic plaques, but did not stain normal skin. Both anti-LC and anti-CC stained suprabasal keratinocytes intracellularly in nonplaque psoriatic skin. Thus, the conformation or structure of TGFβ1 and its localization vary in keratinocytes with distinct differentiation phenotypes suggesting that TGFβ1 is a potential modulator of keratinocyte differentiation in vivo. Selective association of TGFβ1 with nonproliferating keratinocytes in the suprabasal layers of the epidermis and its exclusion from the proliferating keratinocytes in the basal layer suggest that it may be a Physiological regulator of keratinocyte proliferation. In addition, the intracellular localization of TGFβ1 peptide in both normal and psoriatic keratinocytes suggests that it is constitutively synthesized by epidermal keratinocytes in vivo.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041440119
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  • 6
    Electronic Resource
    Electronic Resource
    Importance of tyrosine phosphatases in the effects of cell-cell contact and microenvironments on EGF-stimulated tyrosine phosphorylation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 151 (1992), S. 433-442 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have compared the EGF responses of A431 cells when grown as monolayers at a variety of cell densities of as multicellular spheroids in order to investigate the effects of cell contact and 3-dimensional structure on signal transduction. Proliferation of the A431 squamous carcinoma cell line grown in our laboratory was unaffected by EGF when grown in monolayer culture. As 3-dimensional, multicellular spheroids, however, growth was stimulated by EGF. The maximum volume attainable in the presence of EGF was more than 30 times that in its absence. EGF-dependent tyrosine phosphorylation was compared under these conditions by immunohistochemistry and Western blotting. In initial experiments using published procedures, tyrosine phosphorylation was density-dependent in monolayers and undetectable in spheroids. However, the density-dependence was abolished by the addition of high concentrations of protein tyrosine phosphatase inhibitors (1 mM Zn++ and VO43-). The density dependence of EGF-stimulated tyrosine phosphorylation in monolayers was, therefore, largely the result of changes in phosphatase activity rather than kinase. Using high concentrations of phosphatase inhibitors, phosphotyrosine was clearly visible by immunohistochemistry in the outermost cells of spheroids, but it was still not visible in the spheroid center. The lack of response within the spheroid was not related to the presence of EGF receptor nor diffusion of EGF. In companion experiments, we showed that staining for EGF receptor was present homogeneously throughout the spheroid and that EGF penetrated to its center under the conditions of the experiment. Thus, although an increase in tyrosine phosphatase activity was a major factor affecting tyrosine phosphorylation in the outer cells, other factors were important in the inner cells. We concluded that an increase of tyrosine phosphatase activity was the most important component of the adaptation of the EGF signal transduction system to high cell density in monolayer cultures. In spheroids, tyrosine phosphatases are also enhanced, but other factors, such as autocrine synthesis of TGF-α and possibly the cellular distribution of EGF receptors and cell shape, play a role. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041510302
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  • 7
    Electronic Resource
    Electronic Resource
    Adaptation of EGF receptor signal transduction to three-dimensional culture conditions: Changes in surface receptor expression and protein tyrosine phosphorylation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 161 (1994), S. 374-382 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A431 cells grown as three-dimensional spheroids show growth stimulation in response to nanomolar concentrations of EGF in contrast to monolayer cultures that show inhibition. In investigating the alterations in EGF signal transduction that underlie this modification of the proliferative response, we have compared the expression of EGF receptors on A431 cells under these conditions and related our findings to tyrosine phosphorylation and the growth response. EGF receptors were measured by 125I-EGF binding to trypsin-dispersed cells. Unexpectedly, dispersion of the monolayers caused an 80% decrease in surface EGF receptor, although, after dispersion, EGF receptor was digested by trypsin with a half-life of 69 ± 32 min. No evidence for a comparable loss of cellular EGF receptor was seen on trypsin dispersion of spheroids. After allowing for this effect, we found that the receptor density on nondispersed monolayers (5 × 106 per cell) was twentyfold greater than that on spheroids (0.25 × 106 per cell). EGF-induced tyrosine phosphorylation was confined to the outermost cells of the spheroid, although the presence of surface-expressed EGF pinding sites could be demonstrated throughout the structure and the number of EGF receptors/cell on dispersed spheroid cells showed a single distribution peak by flow cytometry, with no evidence for more than one population. Using RCM-lysozyme as a substrate, tyrosine phosphatase activity in spheroids lay within the range observed in monolayer cultures. Autophosphorylation of the EGF receptor following EGF stimulation in monolayer cultures of A431 cells rose rapidly in the first 10 seconds and then slowly increased for at least 3 h. In spheroids, it reached a maximum within 10 seconds and then declined over 3 h. Since the microenvironment within a tumor resembles that in a spheroid, a similar reduction in surface EGF receptor expression may be expected in tumors relative to monolayer cultures, together with corresponding growth stimulation in response to EGF. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041610223
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