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41.
Human papilloma virus E6/E7 genes can expand the lifespan of human corneal fibroblasts 总被引:2,自引:0,他引:2
Donna M. Peters Nathan Dowd Curtis Brandt Teresa Compton 《In vitro cellular & developmental biology. Animal》1996,32(5):279-284
Summary Human corneal fibroblasts were infected with a retroviral delivery vector containing the E6 and E7 genes from human Papilloma
virus type 16 in order to produce cell lines that have an expanded lifespan in culture. Morphologically, some of the trasfected
corneal fibroblast lines appeared to have the normal spindle-shape morphology of diploid fibroblasts, whereas other lines
appeared to have a more elongated morphology. All the cell lines were anchorage-dependent. Cells that had a normal morphology
grew at a rate similar to normal diploid human corneal fibroblasts and had a population doubling time of 48 h. All E6/E7 expressing
cell lines, regardless of morphology, produce types I, III, and V collagen, at levels similar to those observed in the parent
corneal diploid fibroblast. These corneal fibroblast lines will be a usefulin vitro system to study collagen expression and fibril formation, as well as normal stroma development. These results also demonstrate
that the use of E6/E7 genes to expand a cell’s lifespan can be a powerful tool because it does not appear to alter either
the growth rate of the cell or collagen expression. 相似文献
42.
Susan J. Holt Peter Alexander Chris B. Inman Donna E. Davies 《Experimental cell research》1995,217(2)
Ligand-induced translocation of epidermal growth factor receptors (EGF-R) to the nucleus of NR6/HER fibroblasts has been studied by immunoelectron microscopy. Following treatment of NR6/HER cells with epidermal growth factor (EGF) for 1 h, there was a decrease in EGF-R labeling at the plasma membrane and a corresponding increase in EGF-R in the nucleus. This was preceded by a rapid and sustained increase in nuclear phosphotyrosine content, detectable within 2 min of EGF treatment. EGF-R translocation into the nucleus was completely prevented by 18 h serum starvation prior to treatment with EGF. These results indicate that translocation of EGF-R to the nucleus is a controlled process and they suggest theft EGF-R may directly influence nuclear function. 相似文献
43.
Extracellular polysaccharide of Nostoc commune (Cyanobacteria) inhibits fusion of membrane vesicles during desiccation 总被引:6,自引:0,他引:6
Donna R. Hill Thomas W. Keenan Richard F. Helm Malcolm Potts Lois M. Crowe John H. Crowe 《Journal of applied phycology》1997,9(3):237-248
Cells of the cyanobacterium Nostoc commune secrete a complex, high molecular weight, extracellular polysaccharide (EPS) which
accumulates to more than 60% of the dry weight of colonies. The EPS was purified from the clonal isolate N. commune DRH1.
The midpoint of the membrane phase transition (Tm) of desiccated cells of N. commune CHEN was low (Tm
dry = 8 °C) and was comparable to the Tm of rehydrated cells((Tm)H20 = 6 °C). The EPS was not responsible for the depression of Tm. However, the EPS, at low concentrations, inhibited specifically the fusion of phosphatidylcholine membrane vesicles when
they were dried in vitro at0% relative humidity (−400 MPa). Low concentrations of a trehalose:sucrose mixture, in a molar
ratio which corresponded with that present in cells in vivo, together with small amounts of the EPS, were efficient in preventing
leakage of carboxyfloroscein (CF) from membrane vesicles. Freeze-fracture electron microscopy resolved complex changes in
the structure of the EPS and the outer membrane in response to rehydration of desiccated cells. The capacity of the EPS to
prevent membrane fusion, the maintenance of a low Tm
dry in desiccated cells, and the changes in rheological properties of the EPS in response to water availability, constitute what
are likely important mechanisms for desiccation tolerance in this cyanobacterium.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
44.
Mary C. O'Sullivan Qibing Zhou Zhili Li Timothy B. Durham Donna Rattendi Schennella Lane Cyrus J. Bacchi 《Bioorganic & medicinal chemistry》1997,5(12):2145-2155
Trypanothione reductase (TR) occurs exclusively in trypanosomes and leishmania, which are the etiological agents of many diseases. TR plays a vital role in the antioxidant defenses of these parasites and inhibitors of TR have potential as antitrypanosomal agents. We describe the syntheses of several spermine and spermidine derivatives and the inhibiting effects of these compounds on T. cruzi TR. All of the inhibiting compounds displayed competitive inhibition of TR-mediated reduction of trypanothione disulfide. The three most effective compounds studied were N4,N8-bis(3-phenylpropyl)spermine (12), N4,N8-bis(2-naphthylmethyl)spermine (14), and N1,N8-bis(2-naphthylmethyl)spermidine (21), with Ki values of 3.5, 5.5 and 9.5 μM, respectively. Compounds 12, 14, and 21 were found to be potent trypanocides in vitro with IC50 values ranging from 0.19 to 0.83 μM against four T. brucei ssp. strains. However, these compounds did not prolong the lives of mice infected with trypanosomes. This work indicates that certain polyamine derivatives which target a unique pathway in Trypanosomatidae have potential as antitrypanosomal agents. 相似文献
45.
Michael Garrick Donna Scott Susannah Walpole Eric Finkelstein Joy Whitbred Sandeep Chopra Lalitha Trivikram David Mayes Daphne Rhodes Kimberly Cabbagestalk Rahmi Oklu Adnan Sadiq Brett Mascia James Hoke Laura Garrick 《Biometals》1997,10(2):65-76
Belgrade rats inherit microcytic, hypochromic anemia as an autosomalrecessive trait (gene symbol b). Erythrocytes and tissue are iron deficientin the face of elevated TIBC (total iron binding capacity) and percent ironsaturation; iron injections increased the number of erythrocytes but theirappearance remained abnormal. We have investigated iron supplements toimprove husbandry of b/b rats and to learn more about the underlying defectand its tissue distribution. Weekly IM (intramuscular) injections ofiron–dextran (Imferon at 30 mg kg) improved the anemia but did not alter thered cell morphology. Certain diets also improved the health of b/b rats whencompared to standard rat chows by the criteria of weight, survival toadulthood, hematology and reproduction. The critical nutritional factorturned out to be iron bioavailability, with ferrous iron added to the dietimproving the health of Belgrade rats without affecting the underlyingerythroid defect. Tissue iron measurements after dietary or parenteralsupplementation confirmed the iron deficient status of untreated b/b rats andestablished that dietary ferrous iron partially relieved this deficiency,with injections leading to greater amounts of tissue iron. Serum iron andTIBC were also found to be elevated in untreated b/b rats, with dietarysupplementation decreasing but not eliminating the elevation in TIBC. Thesestudies indicate that iron supplements can improve the health of b/b ratswithout altering the underlying defect and also suggest that the mutationcould alter iron uptake in the GI (gastrointestinal) tract. 相似文献
46.
Gosselin Luc E.; Megirian David; Rodman Joshua; Mueller Donna; Farkas Gaspar A. 《Journal of applied physiology》1997,83(4):1405
Gosselin, Luc E., David Megirian, Joshua Rodman, DonnaMueller, and Gaspar A. Farkas. Respiratory muscle reserve in ratsduring heavy exercise. J. Appl.Physiol. 83(4): 1405-1409, 1997.The extent towhich the respiratory pump muscles limit maximal aerobic capacity inquadrupeds is not entirely clear. To examine the effect of reducedrespiratory muscle reserve on aerobic capacity, whole bodypeak oxygen consumption(O2 peak) wasmeasured in healthy Sprague-Dawley rats before and after Sham,unilateral, or bilateral hemidiaphragm denervation (Dnv) surgery.O2 peak wasdetermined by using a graded treadmill running test.Hemidiaphragm paralysis was verified after testing byrecording the absence of electromyographic activity duringinspiration. Before surgery, O2 peak averaged 86, 87, and 92 ml · kg1 · min1for the Sham, unilateral, and bilateral Dnv groups, respectively. Twoweeks after surgery, there was no significant change inO2 peak foreither the Sham or unilateral Dnv group. However,O2 peak decreased~19% in the bilateral Dnv group 2 wk after surgery. These findingsstrongly suggest that the pulmonary system in rats is designed suchthat during heavy exercise, the remaining respiratory pump muscles areable to compensate for the loss of one hemidiaphragm, but not of both. 相似文献
47.
The thermotactic responses of Dictyostelium discoideum strain HL50 and mutants derived from this strain have been characterized by curves of stimulus-strength vs response. With gradient midpoint temperatures of 16 and 24 °C, these curves are typical of those of a single response, i.e., the strength of the response increases with increasing stimulus strength until at some strength the response saturates. However, with a gradient midpoint temperature close to the transition from negative to positive thermotaxis, the sign of the thermotactic response depends on gradient strength. These observations support the hypothesis that the transduction pathways for positive and negative thermotaxis act concurrently and contain separable elements. An investigation of the adaptation of thermotaxis indicated that the stimulus-strength-dependence and midpoint-temperature-dependence of both thermosensory responses was altered by shifting the growth and development temperature. 相似文献
48.
R De Luca A Renzulli V Di Donna A Sicuranza C Sellitto P Mangano L Iovino 《Bollettino della Società italiana di biologia sperimentale》1984,60(4):739-744
In this research we have determined the behaviour of proteic plasmatic pattern and some enzymes during extracorporeal circulation and we noted a constant increase of albumin and of the ratio Alb/Glob. We observed also variations of some enzymes. Our opinion according other AA. is that this changes are determined principally by the large dose of heparin necessary during the C.E.C. 相似文献
49.
Donna F. Brown Thomas W. Honeyman James G. Dobson Jr. 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,544(3):462-473
The effects of epinephrine on cyclic AMP content and protein kinase activity were examined in an in situ rat heart preparation. Bolus injection of epinephrine into the superior vena cava caused an increase in the activity ratio (—cyclic AMP/+cyclic AMP) of 12 000 × g supernatant protein kinase. The increase was significant within 5 s and maximal in 10 s. Epinephrine produced a dose-dependent increase in both protein kinase activity ratio and cyclic AMP content. The increases in both parameters exhibited a high degree of correlation. The increase in protein kinase activity ratio observed with low doses of epinephrine (less than or equal to 1 μg/kg) resulted from an increase in independent protein kinase activity (—cyclic 2 AMP) without a change in total protein observ activity (+cyclic AMP). However, the increase in the activity ratio observed with higher doses of epinephrine (greater than 1 μg/kg) was due mainly to a decrease in total protein kinase activity rather than a further increase in independent protein kinase activity. The loss of supernatant total protein kinase activity could be accounted for by an increase in activity associated with particulate fractions obtained from the homogenates. A similar redistribution of protein kinase could be demonstrated by the addition of cyclic AMP to homogenates prepared from hearts not stimulated with epinephrine. These results demonstrate that epinephrine over a wide dose range produces a parallel increase in the content of cyclic AMP and the activation of soluble protein kinase. The findings also suggest that protein kinase translocation to particulate material may depend on the degree of epinephrine-induced enzyme activation. 相似文献
50.
Satish Walia Glenda Dunn Kathryn Rose Thomas Pinkerton Nicholas Muzyczka Donna Duckworth 《Molecular & general genetics : MGG》1982,185(1):37-42
Summary A cleavage site map of the colicin Ib plasmid (ColIb) has been determined for the enzymes Sall, XhoI, and HindIII by analysis of partial digests, double digests, DNA-DNA hybridization, and Tn5-induced insertion mutants. The site of the colicin gene has been determined by probing with cloned DNA coding for colicin production, as well as by analysis of a colicin negative ColIb:Tn5. 相似文献