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  • 1
    Electronic Resource
    Electronic Resource
    An HSV-1 Vector Containing the Rat Tyrosine Hydroxylase Promoter Enhances Both Long-Term and Cell Type-Specific Expression in the Midbrain (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 68 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A defective herpes simplex virus type one (HSV-1) vector that contains a 6.8-kb fragment of the rat tyrosine hydroxylase promoter (pTHlac-7kb) was examined for its capability to target catecholaminergic cell type-specific expression in the CNS. Cell type-specific expression was assessed by comparison with a control vector (pHSVlac) that uses the HSV-1 immediate early 4/5 promoter to support expression in multiple cell types. In initial experiments comparing expression in catecholaminergic and noncatecholaminergic cell lines, pTHlac-7kb supported a seven- to 20-fold increase in reporter gene expression in catecholaminergic cell lines. Four days after stereotactic injection into the midbrain of adult rats, pTHlac-7kb supported a 10-fold targeting of β-galactosidase expression to tyrosine hydroxylase-expressing neurons in the substantia nigra pars compacta compared with pHSVlac. Expression from pTHlac-7kb was stably maintained for 6 weeks with no significant changes in the pattern of expression. Long-term expression from pTHlac-7kb was confirmed by RNA and DNA analysis. In contrast, reporter gene expression in the midbrain from pHSVlac decreased ∼30-fold between 4 days and 6 weeks after gene transfer. Thus, within the context of this HSV-1 vector system, the tyrosine hydroxylase promoter enhanced cell type-specific expression and contributed to stable, long-term expression of a recombinant gene product in neurons. The capability to target recombinant gene expression to catecholaminergic neurons in specific brain areas may be useful for studies on the roles of these neurons in brain physiology and behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.68051792.x
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative studies of glucose-fed and glucose-starved hamster cell cultures: Responses in galactose metabolismThis work was supported by grants from the American Cancer Society BC-120 and the National Institutes of Health AM-05507 and the National Science Foundation BMS71-01291 A03. This is publication No. 1517 of the Cancer Commission of Harvard University. (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 387-405 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The metabolic flow of trace amounts of D-[14C]-galactose was followed in cultures of transformed and untransformed hamster cells over a period ranging from five minutes to two hours. The results of chromatographic and enzymatic analyses of the soluble pools are described. Non-glycolytic cells (previously deprived of sugar for periods of up to 24 hours) convert D-galactose to galactose-1-phosphate and uridine diphosphoglucuronic acid in 10 to 20 minutes. In the same short assay time, glycolytic cells which have been maintained for 24 hours in media containing glucose or galactose convert D-galactose to uridine diphosphogalactose and uridine diphosphoglucose (ratio 1.4:1). Longterm deprivation of sugar also results in 3- to 4-fold increases in the uptake of galactose. In addition, the incorporation of galactose label into chloroform-methanol soluble material appears to be influenced by the culture conditions of the untransformed cells while incorporation in the transformed cells appears unaffected. When cycloheximide is included in the maintenance medium for extended periods, the non-glycolytic cells also show increases in galactose uptake rates but the glucose-fed, glycolytic cells lose uptake ability. UDPhexose is the main galactose metabolic peak in the soluble pools of the cycloheximide-treated, glycolytic and the cycloheximide-treated, non-glycolytic cells. The results of these experiments suggest that uptake of galactose and its subsequent metabolism are under separate control.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040900303
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  • 3
    Electronic Resource
    Electronic Resource
    Further observations on metabolic responses in hamster cells: Changes in udpg dehydrogenase activity (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 96 (1978), S. 23-29 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Administration of radioactively labeled galactose to cultured mammalian cells brings about an accumulation of metabolic products the pattern of which seems to be governed by a variety of vectors in the intracellular milieu. By manipulation of culture conditions some of these vectors appear to be a function of glycolysis. In the non-glycolytic culture, label from a galactose probe appears as Galactose-1-phosphate (Gal-1-P) and UDPglucuronic acid (UDPGlcUA). Conversely, glycolytic culture conditions seem not to permit the formation to UDPGlcUA since the only labeled accumulation product formed was UDPHex. A suggestion is made that the difference in metabolic activity of glucose-fed and glucose-starved cultures may be related to the effect of NADH on the in situ activity of UDPG dehydrogenase (UDPglucose:NAD oxidoreductase, E.C. 1.1.1.22) (abbreviation, UDPG-DH). This prompted an investigation of the effects of NAD and NADH on the activity of partially purified UDPG-DH. The results of these experiments strongly suggest that the activity of UDPG-DH (in situ) is negatively controlled by increased levels of NADH; the latter condition is known to exist in glycolytically active cells (Schwartz and Johnson, 1976). Added to this is a second control mechanism which is characterized by a transient inhibition of uridylyltransferase (UDP glucose:α-D-galactose-1-phosphate uridylyltransferase, E.C. 2.7.7.12). Since it is known that there is little, if any, effect on galactokinase (ATP:D-galactose-1-phosphotransferase, E.C. 2.7.1.6) activity as a result of sugar starvation (Christopher et al., 1976), the low in vivo activity of uridylyltransferase contributes not only to the increased accumulation of Gal-1-P but also to a drastic decrease of labeled UDPhexoses, although the pre-existing pool of UDPhexose was found to decrease only moderately under the condition of glucose starvation (30% still persisted). The benefit of this type of control is not clear.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040960104
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  • 4
    Electronic Resource
    Electronic Resource
    Selective high metabolic lability of uridine, guanosine and cytosine triphosphates in response to glucose deprivation and refeeding of untransformed and polyoma virus-transformed hamster fibroblasts (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 229-235 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sugar deprivation of hamster fibroblasts (NILAbbreviations: ATP, ADP and AMP, adenosine 5′-tri-, di- and monophosphate respectively; CTP, CDP and CMP, cytosine 5′-tri-, di and monophosphate respectively; GTP, GDP and GMP, guanosine 5′-tri-, di- and monophosphate respectively; IMP, inosine 5′-monophosphate; Gal-1-P, α-D-galactose-1-phosphate; UDP-Gal, uridine 5′-diphosphogalactose; D-MEM, Dulbecco's modified Eagle's minimal essential medium; D-PBS, Dulbecco's phosphate-buffered saline (pH 7.2); NIL, a line of Syrian hamster fibroblasts; PyNIL, a polyoma virus-transformed line of NIL cells.) affected the steady state levels (pool sizes) of cellular acid soluble nucleotides in the following fashion; the pools of UTP, GTP and CTP decreased to a much greater extent than the cellular ATP pools, with the UTP pools undergoing the most dramatic reduction. Sugar deprivation of polyoma-transformed NIL cells (PyNIL) yielded even sharper decreases in the nucleoside triphosphate pools with relative changes similar to those of the untransformed cells. Inhibition of protein synthesis by cycloheximide, initiated at the onset of (and continued during) sugar deprivation, prevented the reduction in pool sizes and yielded values slightly higher than those observed for pool sizes in cells cultured in sugar-supplemented medium. Refeeding glucose to sugar-depleted hamster fibroblasts led to rapid increases (within 1 hour) in the UTP and CTP pools to levels well above the pool sizes observed in cells which were continuously cultured (16 hours) in sugar supplemented medium. Feeding NIL or PyNIL cells with fructose instead of glucose as the only hexose source did not appreciably affect any of the ribonucleoside triphosphate pool sizes. Measurements of hexose uptake by NIL and PyNIL cells under a variety of conditions suggest that hexose transport is not regulated by the total cellular pools of ATP or any of the other ribonucleoside triphosphates.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041010205
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  • 5
    Electronic Resource
    Electronic Resource
    Selective high metabolic lability of uridine triphosphate in response to glucosamine feeding of untransformed and polyoma virus-transformed hamster fibroblasts (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 253-259 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Derepression of hexose transport in a line of Syrian hamster fibroblasts (Nil) and polyoma-transformed (PyNil) hamster fibroblasts is obtained when cells are either starved for glucose or fed with fructose as the only hexose source. D-glucosamine feeding of these cells does not alter the repressed state with regard to hexose transport. High, derepressed rates of galactose transport were changed to low, repressed rates, within 18 hours of refeeding glucose-starved cells with D-glucosamine as the only hexose source. Nil and PyNil cells, when cultured in the presence of D-glucosamine, undergo rapid reductions in total cellular uridine 5′-triphosphate (UTP) pool sizes. By contrast, the total cellular pools of adenosine 5′-triphosphate, guanosine 5′-triphosphate, and cytosine 5′-triphosphate (ATP, GTP, and CTP) were only moderately affected by the treatment of the cells with glucosamine. The metabolic drain of the UTP pools in PyNil cells was much more pronounced than in the untransformed cells. The larger and more rapid metabolic lability of UTP pools in the transformed cells may be the primary reason for the selective toxicity of glucosamine on tumor cells. A comparison of the effects of glucosamine on hexose-starved Nil and PyNil cells demonstrated that only the untransformed cells were able to utilize glucosamine to increase the hexose starvation-depleted pools of all nucleoside triphosphates. Accumulation of UDP-glucosamine and UDP-N-acetylglucosamine followed the reduction in the UTP pools. Inhibition of protein synthesis by cycloheximide during glucosamine feeding led to higher levels of UDP-glucosamine and UDP-N-acetylglucosamine accumulation. It is suggested that the drain of UTP pools during glucosamine treatment proceeds through the formation of the UDP-aminosugars which turn over due to the action of intracellular UDP-aminosugar pyrophosphatase activities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041040216
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  • 6
    Electronic Resource
    Electronic Resource
    Derepression and carrier turnover: Evidence for two distinct mechanisms of hexose transport regulation in animal cells (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 89 (1976), S. 683-692 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hexose uptake by hamster cells was increased five to ten fold by either substituting D-fructose for glucose or by completely omitting D-glucose from the culture medium for 24 to 48 hours. Conversely, when cycloheximide was present for 24 hours in media containing glucose, up to 20-fold decreases in hexose uptake were observed. However, these decreases in uptake activity were only observed over a narrow range of cycloheximide concentrations. After extended exposure to low concentrations of cycloheximide (0.05 to 10 μg/ml), the uptake by the fed cells decreased parallel with inhibition of protein synthesis whereas at high concentrations (〉50 μg/ml) uptake was increased. Cells deprived of glucose and maintained in the presence of cycloheximide did not show decreases in uptake activity. In separate experiments the high uptake rates of glucose-starved cells could be decreased by addition of glucose to the glucose-free medium. The reversal was complete in 6 to 8 hours. The analog of glucose, 2-deoxy-D-glucose, did not promote the time-dependent decrease suggesting that the 6-phosphoester of glucose is not an inhibitor of transport. In addition, when cycloheximide is added at the same time as glucose, there is no decrease in uptake for at least 12 hours. We propose that turnover of components of hexose uptake systems could account for part of the control of hexose transport. Moreover, the results indicate that the turnover mechanism becomes inactive during glucose starvation and must be resynthesized following refeeding of the starved cells with glucose.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040890427
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