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  • 1
    Electronic Resource
    Electronic Resource
    Folding in vitro of bovine pancreatic trypsin inhibitor in the presence of proteins of the endoplasmic reticulum (1992)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 14 (1992), S. 10-15 
    Details
    ISSN: 0887-3585
    Keywords: protein disulfide isomerase ; disulfide bonds ; protein folding ; chaperones ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The rate of folding and disulfide bond formation in reduced BPTI were measured in vitro in the presence and absence of total protein from the endoplasmic reticulum. The rates were increased substantially by the endoplasmic reticulum proteins, but only to the extent expected from the known content and activity of protein-disulfide-isomerase. No effects of added ATP or Ca2+ were observed, even though protein-disulfide-isomerase blinds Ca2+ tightly. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340140104
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of cellular rate distributions in microbial cell populations: Feeding rates of ciliated protozoa (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 284-294 
    Details
    ISSN: 0006-3592
    Keywords: ingestion rate distribution ; population balance ; state properties ; rate properties ; flow cytometry ; particle uptake model ; Poisson process model ; Tetrahymena pyriformis ; suspension feeding ; filter feeding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel procedure is proposed for determining distributions of rate properties and correlations of rate with state properties of microbial cell populations. The procedure is novel in that it uses transient data, and thus, it does not require that the population be in balanced growth, although it requires that the population structure does not change during the short transient experiment. The procedure is applied to populations of the ciliated protozoan Tetrahymena to determine ingestion rate variability. The number of ingested microspheres per cell and the single-cell protein content - an indicator of cell size - were directly determined with dual-color flow cytometry. The proposed technique revealed the correlation pattern of the particle ingestion rate with cell size. In particular, ingestion rate was found to be positively correlated with cell size for the smaller feeding cells and to be uncorrelated with size for the larger cells. Using the fact that particle uptake from dilute particle suspensions is a Poisson random process, we determined that the coefficient of variation of the distribution of ingestion rates within the feeding population is about 50%. It was concluded that the dynamics of particle ingestion can be accurately described only if it is realized that particle ingestion rates are distributed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420304
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  • 3
    Electronic Resource
    Electronic Resource
    Insertion of microscopic objects through plant cell walls using laser microsurgery (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 348-355 
    Details
    ISSN: 0006-3592
    Keywords: Agrobacterium rhizogenes ; laser heating ; Ginkgo biloba ; optical scalpel ; optical tweezers ; plant cell culture ; plasmolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A detailed protocol is presented for precisely inserting microscopic objects into the periplasmic region of plant callus cells using laser microsurgery. Ginkgo biloba and Agrobacterium rhizogenes were used as the model system for developing the optical tweezers and scalpel techniques using a single laser. We achieved better than 95% survival after plasmolyzing G. biloba cells, ablating a 2-4-μm hole through the cell wall using a pulsed UV laser beam, trapping and translating bacteria into the periplasmic region using a pulsed infrared laser beam, and then deplasmolyzing the cells. Insertion of bacteria is also described. A thermal model for temperature changes of trapped bacteria is included. Comparisons with other methods, such as a reverse-pressure gradient technique, are discussed and additional experiments on plants using laser microsurgery are suggested. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 348-355, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Cell cycle regulation by environmental pH (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 517-525 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Purified populations of quiescent human tumour cells were isolated from plateau phase cultures of PMC-22 cells by centrifugal elutriation. Dilution into fresh medium resulted in these quiescent cells entering S phase exponentially with a t1/2 of 12 hr, after a 18-20-hr lag period during which cellular RNA content increased. Subsequent studies showed that recruitment of quiescent cells into the cell cycle could be regulated by extracellular pH. When exponentially growing PMC-22 cells were exposed to acidic extracellular pH levels, three growth patterns were observed: (1) Normal growth between pH 7.2 to pH 6.8; (2) A reduction in growth rate associated with accumulation of cells with a G1 DNA content between pH 6.7 and 6.4 (this was also shown to occur in a number of other tumour cell lines); (3) Non-cell-cycle-phase-specific arrest of growth at pH levels less than 6.3. Further studies with purified quiescent cell populations showed the possible existence of a pH-dependent restriction point in the G1 phase of these tumour cells. The implications of these observations to tumour biology are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041210310
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of hypophysectomy and gonadotropin treatment on follicular development and ovulation in the hamster (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 139 (1974), S. 37-48 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In hamsters hypophysectomized on day 1 of the cycle (morning of ovulation) on days 1-28 post-hypophysectomy 99% of follicular development is limited to small and medium sized follicles with no more than five layers of granulosal cells. Since the largest preantral follicles on day 1 of the cycle have 10-12 layers of granulosal cells, it is evident that follicles become dependent on gonadotropins at an early stage of their maturation.The daily injection of 200 μg ovine follicle stimulating hormone (FSH) on days 8-11 post-hypophysectomy results in large antral follicles; when 10 μg ovine luteinizing hormone (LH) is then injected the animals ovulate 32 eggs. When 200 μg FSH on day 8 post-hypophysectomy is followed by 50 μg FSH on days 9-11, injecting LH results in the ovulation of nine eggs  -  comparable to the ovulation rate of intact hamsters. These experiments indicate that superovulation depends on sustained high levels of FSH whereas the ovulation of a normal number of eggs requires an initially high level of FSH and then much lower maintenance levels.When replacement therapy with 200 μg FSH for four days is started on the day of hypophysectomy (day 1) or day 2, follicles fail to develop past the six-seven granulosal layer stage. However, deferring the initial injection of FSH until day 3 results in antral follicles that are ovulated by LH (ovulation = 36 eggs). This suggests that functional corpora lutea inhibit the effects of FSH on follicular growth. Progesterone administered to hypophysectomized hamsters (days 8-11 post-hypophysectomy) increases the percentage of medium follicles at the expense of smaller stages. Progesterone injected daily along with FSH also prevents follicular development past the six-seven granulosal layer stage in 14 of 24 hypophysectomized animals.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001390103
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  • 6
    Electronic Resource
    Electronic Resource
    Thrombospondin mediates migration and potentiates platelet-derived growth factor-dependent migration of calf pulmonary artery smooth muscle cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 157 (1993), S. 24-32 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A precipitating factor in the development of atherosclerotic lesions is the inappropriate migration and proliferation of vascular smooth muscle cells (SMC) within the intima of the vessel wall. Focusing on the role of extracellular matrix proteins in SMC migration, we have demonstrated that thrombospondin (TSP) itself is a potent modulator of SMC motility and acts to potentiate platelet-derived growth factor (PDGF)-mediated SMC migration as well. Migration of SMC to TSP was dose dependent. Interestingly, maximal SMC migration to TSP exceeded that to either PDGF or basic fibroblast growth factor (bFGF). The distal COOH terminus of TSP was shown to mediate SMC migration as demonstrated by complete inhibition of the response by monoclonal antibody (mAb) C6.7. Nevertheless, proteolytic fragments of TSP were not as potent as intact TSP in mediating SMC migration. Only by combining the heparin-binding domain (HBD) with the 140 kD COOH terminal fragment was SMC migration restored to levels seen with intact TSP. Based on antibody inhibition studies, an αv-containing integrin receptor, but not αvβ1 or αvβ3, appeared to be involved in SMC migration to TSP. The coincidental expression of PDGF and TSP at sites of vascular injury and inflammation led us to evaluate the effect of suboptimal levels of TSP on SMC responsiveness to PDGF. SMC migration in response to PDGF was enhanced nearly 60% in the presence of suboptimal concentrations of TSP. This effect was specific for PDGF and dependent on the concentration of TSP with maximal potentiation obtained between 50-100 nM TSP, concentrations tenfold lower than those necessary for SMC migration to TSP itself. mAb C6.7 completely inhibited enhancement but, as with SMC migration to TSP alone, TSP proteolytic fragments did not possess the effectiveness of the intact molecule. Additional experiments assessing SMC migration to PDGF demonstrated that PDGF stimulated SMC motility indirectly by inducing TSP synthesis. These studies suggested that TSP functions as an autocrine motility factor to modulate SMC migration, which in conjunction with PDGF could serve to aggravate and accelerate development of atherosclerotic lesions at sites of vascular injury or inflammation. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041570104
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  • 7
    Electronic Resource
    Electronic Resource
    Induction of autocrine epidermal growth factor receptor ligands in human keratinocytes by insulin/insulin-like growth factor-1 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 163 (1995), S. 257-265 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Autocrine activation of the epidermal growth factor (EGF) receptor on keratinocytes has been recognized as an important growth regulatory mechanism involved in epithelial homeostasis, and, possibly, hyperproliferative diseases. Insulin-like growth factor (IGF)-1 and insulin have been shown to be paracrine keratinocyte mitogens that bind to the type I IGF receptor which is expressed on actively proliferating keratinocytes in situ. In this report, we demonstrate that IGF-1/insulin induced production of keratinocyte-derived autocrine growth factors that bind to the EGF receptor. Increased steady-state mRNA levels for transforming growth factor alpha (TGF-α) and for amphiregulin (AR) were observed upon incubation of keratinocytes with mitogenic concentrations of IGF-1. IGF-1 also induced production and secretion of TGF-α and AR proteins as detected by immunoassays. An EGF receptor antagonistic monoclonal antibody abolished the mitogenic effect of IGF-1 on cultured keratinocytes. These results suggest that stimulation of keratinocyte growth by IGF-1 requires activation of an EGF receptor-mediated autocrine loop. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041630206
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  • 8
    Electronic Resource
    Electronic Resource
    Activation of protein kinase C inhibits human keratinocyte migration (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 487-496 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The involvement of protein kinase C (PKC) in epidermal growth factor (EGF)-induced human keratinocyte migration was studied with the phagokinetic assay. It was concluded that PKC activation does not mediate, but rather inhibits, EGF-induced keratinocyte migration. The following experimental observations support these conclusions: 1) The PKC inhibitor H-7 did not inhibit EGF-induced migration but instead led to a modest enhancement. 2) PKC activators such as phorbol-12-myristate-13-acetate (PMA), phorbol-12,13-dibutyrate (PDBu), and 1,2-dioctanoly-sn-glycerol inhibited migration, but biologically inactive 4α-PMA had no effect. 3) PMA did not inhibit keratinocyte attachment and spreading but blocked migration almost immediately after addition. 4) Migration of PKC-depleted cells, which were produced by prolonged treatment with PDBu, was enhanced similarly to normal cells by EGF. 5) PKC-depleted cells were not susceptible to the inhibitory effects of phorbol esters on migration. Additional experiments, in which cells were preactivated with EGF, suggested that PKC inhibits the EGF effect at a post-receptor level. The inhibitory effect of PKC on keratinocyte migration was not restricted to EGF-induced migration; PKC activation also inhibited keratinocyte migration induced by bovine pituitary extract, insulin, insulin-like growth factor-1, and keratinocyte growth factor. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560308
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  • 9
    Electronic Resource
    Electronic Resource
    Autocrine/paracrine regulation of keratinocyte urokinase plasminogen activator through the TGF-α/EGF receptor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 155 (1993), S. 333-339 
    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-α (TGF-α) appears to be an important autocrine/paracrine regulator of keratinocyte function. Not only does TGF-α induce keratinocyte proliferation and migration in vitro, but it also has been detected in normal human epidermis and at elevated levels in hyperproliferative epidermis. In the present study we report that exogenous TGF-α increases urokinase-type plasminogen activator (uPA) in cultured human keratinocytes. Furthermore, in the absence of exogenous growth factors, the “basal” levels of uPA are decreased by an antagonist monoclonal antibody to the receptor shared by TGF-α and epidermal growth factor (EGF). These results suggest that an endogenous factor serves as an autocrine/paracrine regulator of keratinocyte uPA. We hypothesize that activation of the TGF-α/EGF receptor may coordinately regulate the keratinocyte response to cutaneous wounding, which includes enhanced uPA expression, migration, and proliferation. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041550214
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  • 10
    Electronic Resource
    Electronic Resource
    Preferential induction of apoptosis in mouse CD4+CD8+αβTCRIoCD3εIo thymocytes by zinc (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 164 (1995), S. 259-270 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: High concentrations of zinc salts (500 m̈M and greater) are known to inhibit apoptosis in a variety of systems. However, closer examination of dose effects revealed that lower concentrations of zinc (80-200 m̈M) could induce apoptosis in approximately 30-40% of mouse thymocytes following 8 h incubation. The ability of zinc to cause thymocyte apoptosis was detected flow-cytometrically by reductions in propidium iodide DNA fluorescence and forward scatter, both quantitative indicators of apoptotic death. Zinc induced both internucleosomal DNA fragmentation and morphological changes characteristic of apoptosis as determined by gel electrophoresis and electron microscopy, respectively. In addition, transcriptional and translational inhibitors prevented zinc-induced apoptosis, indicating a requirement for de novo mRNA and protein synthesis, another characteristic of apoptotic death. Fluorescent immunophenotype-specific apoptotic analysis indicated that zinc-induced apoptosis occurred primarily in the less mature CD4+CD8+αb̃TCRIoCD3εIo thymocyte subset, with lower amounts of death occurring in the other subsets. This lineage specificity was shared with glucocorticoid-induced apoptosis. Taken together, these results indicate that zinc induces true apopotitic death in mouse thymocytes and suggests a role for zinc in the regulation of apoptosis. © 1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041640206
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