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  • 1990-1994  (12)
  • United States  (4)
  • Computational Chemistry and Molecular Modeling  (3)
  • gene expression  (3)
  • Chilling  (2)
  • 1
    Electronic Resource
    Electronic Resource
    An altered constitutive peptide in sym 5 mutants of Pisum sativum L. (1990)
    Springer
    Plant molecular biology 14 (1990), S. 207-216 
    Details
    ISSN: 1573-5028
    Keywords: developmental mutant ; gene expression ; nodule formation ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutational analysis of Pisum sativum L. was used to search for constitutive proteins that might function in nodule formation. The sym 5 locus is a mutational hot spot, represented by seven independently derived mutant lines with decreased nodulation. Comparison of two-dimensional polyacrylamide gels of in vitro-translated root RNA showed a consistent difference in the migrational pattern of one peptide. In the nodulating parental cultivar ‘Sparkle’, a 66 kDa peptide had a pI of 5.9. In four of the five tested sym 5 mutants, the 66 kDa peptide had a more acidic pI of 5.8. This 66 kDa peptide is found in lateral root, tap root, and shoot. Its expression was independent of rhizobial inoculation, root temperature, or light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018561
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  • 2
    Electronic Resource
    Electronic Resource
    Long-term chilling of young tomato plants under low light and subsequent recovery (1992)
    Springer
    Planta 186 (1992), S. 172-178 
    Details
    ISSN: 1432-2048
    Keywords: Chilling ; Growth (low temperature) ; Lycopersicon (chilling) ; Photosynthesis (chilling effects) ; Stomatal resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of unfavourable climatic conditions at the onset of the growth period on chilling-sensitive tomato (Lycopersicon esculentum Mill., cv. Abunda) was studied by exposing young plants to combinations of low temperature and low light (60–100 μmol quanta · m−2 · s−1) for several weeks. When the temperature did not decrease below a critical point (8 ° C) no loss of developmental capacity of the plants was detected. However, while new leaves were readily formed upon return to normal growth conditions (22/18 °C, day/night, in a greenhouse), net accumulation of biomass showed a lag phase of approximately one week. This delay was accompanied by a strong, irreversible inhibition of photosynthesis in the fully expanded leaves which had been exposed to the chilling treatment. When plants were subjected to temperatures below 8 ° C, survival rates decreased after three weeks at 6 ° C and irreversible damage of apical meristematic tissue occurred. Drought-hardening prior to chilling ensured survival at 6 ° C and protected the plants against meristem loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196246
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  • 3
    Electronic Resource
    Electronic Resource
    Long-term chilling of young tomato plants under low light and subsequent recovery (1992)
    Springer
    Planta 186 (1992), S. 179-187 
    Details
    ISSN: 1432-2048
    Keywords: Chilling ; Chlorophyll fluorescence ; Lycopersicon (chilling) ; Photoinhibition ; Photosynthate partitioning ; Photosynthesis (chilling effects) ; Ribulose-1,5-bisphosphate carboxylase/oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To identify possible reasons for the persisting impairment of photosynthesis after long-term chilling, young tomato (Lycopersicon esculentum Mill.) plants were exposed to 6–10° C for two weeks under low illumination during the daily light period (60–100 μmol quanta · m−2 · s−1). The time courses of leaf carbohydrate contents, phosphorylated intermediates and chlorophyll-fluorescence parameters were followed. While starch formation was impaired during chilling at 6° C, soluble sugar contents increased from the first day onwards and reached up to eightfold the values found in unchilled plants within two weeks. At 8 and 10° C, a less drastic increase in soluble-carbohydrate contents was observed. During chilling, glucose-6-phosphate and fructose-6-phosphate accumulated up to 16 mM (assuming they are restricted to the cytoplasm). At the same time, non-photochemical quenching of chlorophyll fluorescence had increased and did not return to control values during the first week of recovery. The 3-phosphoglyceric acid/triose phosphate ratio remained nearly unaffected by the chilling treatment, indicating that the assimilatory power of the plants was still high even at the low temperatures. As a consequence of the chilling treatment, ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco) activity in the chilled leaves was irreversibly decreased. It is suggested that, in addition to a possible (orthophosphate-mediated) feedback inhibition by internal sugar accumulation, the low activity of Rubisco can play a significant role in the strong decrease of photosynthetic capacity during long-term chilling in tomato.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196247
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  • 4
    Electronic Resource
    Electronic Resource
    Sugar, meat, and fat intake, and non-dietary risk factors for colon cancer incidence in Iowa women (United States) (1994)
    Springer
    Cancer causes & control 5 (1994), S. 38-52 
    Details
    ISSN: 1573-7225
    Keywords: Anthropometry ; colonic neoplasms ; dietary fats ; females ; lifestyle ; meat ; prospective studies ; reproduction ; sucrose ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate the relation of dietary intakes of sucrose, meat, and fat, and anthropometric, lifestyle, hormonal, and reproductive factors to colon cancer incidence, data were analyzed from a prospective cohort study of 35,215 Iowa (United States) women, aged 55–69 years and without a history of cancer, who completed mailed dietary and other questionnaires in 1986. Through 1990, 212 incident cases of colon cancer were documented. Proportional hazards regression was used to adjust for age and other risk factors. Risk factors found to be associated significantly with colon cancer included: (i) sucrose-containing foods and beverages other than ice cream/milk; relative risks (RR) across the quintiles=1.00, 1.73, 1.56, 1.54, and 2.00 (95% confidence intervals [CI] for quintiles two and five exclude 1.0); (ii) sucrose; RR across the quintiles=1.00, 1.70, 1.81, 1.82, and 1.45 (CI for quintiles two through four exclude 1.0); (iii) height; RR=1.23 for highest to lowest quintile (P for trend-0.02); (iv) body mass index; RR=1.41 for highest to lowest quintile (P for trend=0.03); and (v) number of livebirths, RR=1.59 for having had one to two livebirths and 1.80 for having had three or more livebirths compared with having had none (P for trend=0.04). These data support hypotheses that sucrose intake or being tall or obese increases colon cancer risk; run contrary to the hypothesis that increased parity decreases risk; support previous findings of no association with demographic factors other than age, cigarette smoking, or use of oral contraceptives or estrogen replacement therapy; and raise questions regarding previous associations with meat, fat, protein, and physical activity.Cancer Causes and Control 1994, 5, 38–52.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01830725
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  • 5
    Electronic Resource
    Electronic Resource
    Difficulty becoming pregnant and family history as interactive risk factors for postmenopausal breast cancer: the Iowa Women's Health Study (1993)
    Springer
    Cancer causes & control 4 (1993), S. 21-28 
    Details
    ISSN: 1573-7225
    Keywords: Breast neoplasms ; family history ; infertility ; Iowa Women's Health Study ; nulliparity ; prospective studies ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: We recently provided data from a prospective cohort study of postmenopausal women which suggested that a first livebirth at age 30 or older (cf before age 20) was associated with a twofold increased risk of breast cancer in women without a family history, but a 5.8-fold higher risk in women with a positive family history. To address the question of whether these observations reflect difficulty becoming pregnant or maintaining a pregnancy, we performed additional analyses in which the outcome of each pregnancy was considered. During five years of follow-up, 620 incident cases of breast cancer were identified in the 37,105 women at risk. There was little evidence for an increased risk associated with a history of spontaneous abortion (relative risk [RR]=1.1; 95 percent confidence interval [CI]=0.9–1.4), nor was the risk higher among women who reported two or more spontaneous abortions in consecutive pregnancies (RR=1.0, CI=0.7–1.4). Although women who reported that they had tried unsuccessfully to become pregnant had only slightly and nonsignificantly elevated risks of breast cancer (RR=1.1, CI=0.9–1.3), a more pronounced and statistically significant association was noted in women with a positive family history (RR=2.0, CI=1.4–3.2). There was a strong inverse association between failure to become pregnant and parity (P〈0.0001); nearly 50 percent of the nulliparous married women reported having tried and failed to become pregnant, whereas the frequency was only 6.8 percent among married women with five or more livebirths. Thus, difficulties in becoming pregnant may characterize a subset of women at increased risk of breast cancer, especially in the presence of a family history.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00051710
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  • 6
    Electronic Resource
    Electronic Resource
    Alcohol consumption and postmenopausal endometrial cancer: results from the Iowa Women's Health Study (1993)
    Springer
    Cancer causes & control 4 (1993), S. 323-329 
    Details
    ISSN: 1573-7225
    Keywords: Alcohol ; cohort study ; endometrial cancer ; estrogen replacement therapy ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: At least three case-control studies have examined the association between alcohol consumption and endometrial cancer; two studies showed inverse associations, and a third a positive association. To our knowledge, no prospective studies of this association have been reported. The association between alcohol and endometrial cancer was examined in the Iowa Women's Health Study (United States), a prospective study of postmenopausal women. Information on alcohol consumption and other variables was obtained through a mailed questionnaire in January 1986. Through December 1990, 167 incident endometrial cancer cases occurred in the at-risk cohort of 25,170 women. Multivariate-adjusted relative risks (RR) and 95 percent confidence intervals (CI) were computed using Cox proportional hazards regression controlling for age, body mass index (BMI), parity, age at menopause, and noncontraceptive estrogen use, and to determine multiplicative interactions. The RRs of endometrial cancer associated with 〈4.0 and ≥4.0 g of alcohol per day compared with abstainers were 0.7 (CI=0.5–1.1) and 1.0 (CI=0.7–1.6), respectively. No statistically significant association between endometrial cancer and consumption of either beer, wine, or liquor was observed. There was no interaction between alcohol and any other endometrial cancer risk factors, including BMI or noncontraceptive estrogen use. These data do not support an association between alcohol and endometrial cancer among postmenopausal women.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00051334
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  • 7
    Electronic Resource
    Electronic Resource
    Dietary cholesterol, fat, and lung cancer incidence among older women: The Iowa Women's Health Study (United States) (1994)
    Springer
    Cancer causes & control 5 (1994), S. 395-400 
    Details
    ISSN: 1573-7225
    Keywords: Cholesterol ; cohort study ; diet ; fat ; lung cancer ; nutrition ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To test the hypothesis that a high intake of dietary cholesterol and fat is associated with elevated risks of lung cancer, we analyzed data from a population-based, prospective, cohort study conducted among 41,837 postmenopausal Iowa (United States) women who completed, in 1986, a comprehensive mailed questionnaire including information on usual intake of 127 food items. All cohort members were followed for cancer incidence through the statewide cancer registry. By 1991, after six years of follow-up, 272 incident lung-cancer cases were identified. After controlling for total energy intake and other confounding factors, dietary cholesterol, total fat, and animal fat were unrelated to lung cancer risk. Intake in the upper three quartiles of plantderived fat, however, was related to a 30 to 40 percent lower incidence of lung cancer, compared with those in the lowest quartile, with more pronoucned reduction in risk observed among smokers (relative risk=0.6, 95 percent confidence interval=0.4–0.9). This prospective cohort study suggests that high intake of fat of plant origin may be associated with reduced risk of lung cancer, while dietary cholesterol and animal fat intake is unrelated to the etiology of this malignancy in postmenopausal women.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01694752
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  • 8
    Electronic Resource
    Electronic Resource
    Phenotype suppression: A postulated molecular mechanism for mediating the relationship of proliferation and differentiation by Fos/Jun interactions at AP-1 sites in steroid responsive promoter elements of tissue-specific genes (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 9-14 
    Details
    ISSN: 0730-2312
    Keywords: oncogenes ; osteoblasts ; osteocalcin ; alkaline phosphatase ; collagen ; transcription ; gene expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: There is a generalized reciprocal relationship between cell growth and expression of genes that occurs following completion of proliferation, which supports the progressive development of cell and tissue phenotypes. Molecular mechanisms which couple the shutdown of proliferation with initiation of tissue-specific gene transcription have been addressed experimentally in cultures of primary diploid osteoblasts that undergo a growth and differentiation developmental sequence. Evidence is presented for a model which postulates that genes transcribed post-proliferatively are suppressed during cell growth by binding of the Fos/Jun protein complex to AP-1 Promoter sites associated with vitamin D responsive elements of several genes encoding osteoblast phenotype markers (Type I collagen, alkaline phosphatase, osteocalcin).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240450106
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  • 9
    Electronic Resource
    Electronic Resource
    Developmental expression and hormonal regulation of the rat matrix GLA protein (MGP) gene in chondrogenesis and osteogenesis (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 46 (1991), S. 351-365 
    Details
    ISSN: 0730-2312
    Keywords: MGP ; chondrogenesis ; osteogenesis ; gene expression ; vitamin D ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Matrix Gla protein (MGP), a vitamin K dependent protein, has recently been identified in many tissues. However, it is accumulated only in bone and cartilage suggesting that the expression of MGP may be related to the development and/or maintance of the phenotypic properties of these tissues. We systematically evaluated MGP mRNA expression as a function of bone and cartilage development and also as regulated by vitamin D during growth and cellular differentiation. Three experimental models of cartilage and bone development were employed:colon; an in vivo model for endochondral bone formation, as well as in primary cells of normal diploid rat chondrocyte and osteoblast cultures. MGP was expressed at the highest level during cartilage formation and calcification in vivo during endochondral bone formation. In chondrocyte cultures, MGP mRNA was present throughout the culture period but increased only after 3 weeks concomitantly with type I collagen mRNA. In osteoblast cultures, MGP mRNA was expressed during the proliferative period and exhibited increased expression during the period of matrix development. In contrast to osteocalcin (bone Gla protein), this increase was not dependent on mineralization but was related to the extent of differentiation associated with and potentially induced by extracellular matrix formation. During the proliferative period, type I collagen mRNA peaked and thereafter declined, while type I collagen protein steadily accumulated in the extracellular matrix. Constant MGP levels were maintained in the mineralization period of osteoblast differentiation in vitro which is consistent with the constant levels found during the osteogenic period of the in vivo system. MGP mRNA levels in both osteoblasts and chondrocytes in culture were significantly elevated by 1,25-(OH)2D3 (10-8 M, 48 h) throughout the time course of cellular growth and differentiation. Interestingly, when MGP mRNA transcripts from vitamin D treated and untreated chondrocytes and osteoblasts were analyzed by high resolution Northern blot analysis, we observed two distinct species of MGP mRNA in the vitamin D treated chondrocyte cultures while all other cultures examined exhibited only a single MGP mRNA transcript. Primer extension analysis indicated a single transcription start site in both osteoblasts and chondrocytes with or without vitamin D treatment, suggesting that the lower molecular weight MGP message in vitamin D treated chondrocytes may be related to a modification in post-transcriptional processing. In conclusion, these results show that the selective accumulation of MGP in bone and cartilage tissues in vitro may be related to the development and/or maintance of a collagenous matrix as reflected by increases in MGP mRNA during these periods. Moreover, our data suggest that cartilage and bone MGP mRNA may in part be selectively regulated by 1,25-(OH)2D3 at the post-transcriptional level.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240460410
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  • 10
    Electronic Resource
    Electronic Resource
    Binding of flexible ligands to proteins: Valproic acid and its interaction with cytochrome P450cam (1993)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 48 (1993), S. 161-180 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A combined theoretical and experimental study of the binding and interaction of valproic acid (VPA) with the bacterial cytochrome P450cam enzyme and the determination of regio- and stereoselective hydroxylation product distribution was performed. From the experiments, C4—;OH VPA was found to be the predominant hydroxylation product with a small amount of C5—OH VPA formed. The experimental stereoselectivity of hydroxylation was 2R4S 〉 ∼ 2S4R 〉 2R4R 〉 ∼ 2S4S and 2S5 〉 ∼ 2R5. The overall goals of the theoretical study were twofold: (1) to characterize as completely as possible, using energy optimization and molecular dynamics simulations, the interactions of flexible ligands with their target proteins, and (2) to determine the extent to which these results could be used to develop criteria to predict or explain the experimentally observed regio- and stereoselectivity of hydroxylation of the flexible ligands. Among the useful insights into the behavior of flexible ligands upon binding to their traget proteins obtained are (1) a large change in conformation occurs for many conformers of VPA upon binding to P450cam, (2) low- energy conformers of VPA do not necessarily lead to optimum interactions with the target protein, and (3) the most favorable mode of interaction of this flexible ligand with the protein binding site has been identified and found to be a result of strong electrostatic interactions between VPA and both Tyr96 and Asp297. For the study of the hydroxylated VPA products, the challenging aspect of this problem was to determine criteria for weighing the contribution of each of the possible protein-ligand complexes. To this end, various possibilities were examined and compared with the experimental results. No single complex was found to reproduce the observed experimental regio- and stereoselectivity. This result indicates that more than one bioactive form of VPA contributes to its oxidation. Results most consistent with experiment are obtained by using the interaction energy of the protein-ligand complex as a criterion for including its contribution to product formation. Although there are remaining disparities between predicted and observed product distributions, the combined theoretical and experimental effort has led to insights into the modes of interaction of this flexible ligand that lead to its observed product specificity. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560480718
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