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  • 1
    Electronic Resource
    Electronic Resource
    Maternal nutritional status in pregnancy and blood pressure in childhood (1994)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 101 (1994), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To examine the relation between indices of maternal nutrition during pregnancy, including haemoglobin concentration, skinfold thickness and body weight, and the child's blood pressure at 10 to 12 years of age.Design Follow up study of children whose mothers had haemoglobin estimations, weights and skinfold thicknesses recorded during pregnancy.Setting Kingston, Jamaica.Subjects Seventy-seven children whose mothers took part in a prospective study of nutrition during pregnancy in relation to fetal growth.Main outcome measure Blood pressure at 10 to 12 years of age.Results The child's mean systolic pressure adjusted for current weight rose by 2.6 mmHg (95 % CI 0.5–4.6, P= 0.01) for each 1 g/dl fall in the mother's lowest haemoglobin during pregnancy. Mothers with a lower haemoglobin had thinner skinfold thicknesses, especially over the triceps (P= 0.005). In multiple regression analyses, taking account of the child's sex and current weight, there was a strong association between thin maternal triceps skinfold thickness at 15 weeks of gestation and raised blood pressure in the offspring. Taking account of the mother's triceps skinfold thickness abolished the relation between lower haemoglobin and raised blood pressure in the child. Lower weight gain between 15 and 35 weeks of gestation was independently associated with raised children's blood pressure. Systolic pressure rose by 10.7 mmHg (95 % CI 5.7 to 15.6, P= 0.0001) for each log mm decrease in the mother's triceps skinfold thickness, and by 0.6 mmHg (95% CI 0.1 to 1.0, P= 0.02) for each 1 kg decrease in the mother's weight gain during pregnancy.Conclusions These results parallel animal experiments suggesting that impaired maternal nutrition may underlie the programming of adult hypertension during fetal life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1994.tb11911.x
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of maternal anaemia and iron deficiency on the ratio of fetal weight to placental weight (1991)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 98 (1991), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective— To examine the maternal influences which determine large placental weight and a high ratio of placental weight to birthweight. These are known predictors of adult blood pressure.Design— Retrospective analysis of routine obstetric and haematology department records for a large cohort of pregnant women.Setting— John Radeliffe Hospital, Oxford.Subjects— 8684 pregnant women who were delivered between January 1987 and January 1989 and whose records could be linked to the results of two or more pregnancy blood counts.Main outcome measures— Placental weight and the ratio of placental weight to birthweight.Results— Large placental weight was associated with a low maternal haemoglobin and a fall in maternal mean cell volume during pregnancy. The highest ratio of placental weight to birthweight occurred in the most anaemic women with the largest falls in mean cell volume. Large placental weight and a high ratio of placental weight to birthweight were also independently associated with a high maternal body mass index. Maternal smoking reduced placental weight, but increased the ratio of placental weight to birthweight.Conclusions— Anaemia and iron deficiency during pregnancy are associated with large placental weight and a high ratio of placental weight to birthweight. This points to maternal nutritional deficiency as a cause for discordance between placental and fetal growth. This may have important implications for the prevention of adult hypertension, which appears to have its origin in fetal life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1991.tb13510.x
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  • 3
    Electronic Resource
    Electronic Resource
    Isotopic heterogeneity of water in transpiring leaves: identification of the component that controls the δ18O of atmospheric O2 and CO2 (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 17 (1994), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Two direct but independent approaches were developed to identify the average δ18O value of the water fraction in the chloroplasts of transpiring leaves. In the first approach, we used the δ18O value of CO2 in isotopic equilibrium with leaf water to reconstruct the δ18O value of water in the chloroplasts. This method was based on the idea that the enzyme carbonic anhydrase facilitates isotopic equilibrium between CO2 and H2O predominantly in the chloroplasts, at a rate that is several orders of magnitude faster than the non-catalysed exchange in other leaf water fractions. In the second approach, we measured the δ18O value of O2 from photosynthetic water oxidation in the chloroplasts of intact leaves. Since O2 is produced from chloroplast water irreversibly and without discrimination, the δ18O value of the O2 should be identical to that of chloroplast water. In intact, transpiring leaves of sunflower (Helianthus annuus cv. giant mammoth) under the experimental conditions used, the average δ18O value of chloroplasts water was displaced by 3—10 % (depending on relative humidity and atmospheric composition) below the value predicted by the conventional Craig & Gordon model. Furthermore, this δ18O value was always lower than the δ18O value that was measured for bulk leaf water. Our results have implications for a variety of environmental studies since it is the δ18O value of water in the chloroplasts that is the relevant quantity in considering terrestrial plants influence on the δ18O values of atmospheric CO2 and O2, as well as in influencing the δ18O of plant organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1994.tb00267.x
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  • 4
    Electronic Resource
    Electronic Resource
    Disproportionate fetal growth and raised IgE concentration in adult life (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 24 (1994), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. A follow-up study was carried out to determine whether either impaired or disproportionate fetal growth are associated with a raised total serum IgE concentration in men and women aged 50 years. The serum IgE concentration was measured in 146 men and 134 women born in Preston (Lancashire, UK) between 1935 and 1943, whose size at birth had been measured in detail.Sixty-two subjects were found to have an IgE concentration above 80 IU/ml. Compared with subjects with a normal IgE on average they had a 0.30 inch larger head circumference at birth (P -0.004) and weighed 5.6 ounces more at birth (P= 0.04). People with a raised and with a normal IgE were of similar crown-heel length at birth, indicating that in utero those with a raised IgE had had disproportionate growth of the head in relation to the trunk and limbs. The prevalence of a raised IgE rose from 14% in subjects whose head circumference at birth was 13 inches or less to 37% in those whose head circumference was more than 14 inches. This association was independent of gestational age at birth and of the mother's pelvic size and parity. It was also independent of adult physique, social class and smoking, and was similar in men and women. In multiple logistic regression analyses odds ratios of a raised IgE rose progressively to more than 4 as head circumference at birth increased from 13 inches or less to more than 14 inches.One possibility is that these associations reflect the long-term effects of sustaining fetal brain growth at the expense of the trunk, in particular the thymus. This may be a consequence of fetal under-nutrition in late gestation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.1994.tb00968.x
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  • 5
    Electronic Resource
    Electronic Resource
    Chlorophyll fluorescence in the resurrection plant Selaginella lepidophylla (Hook. & Grev.) Spring during high-light and desiccation stress, and evidence for zeaxanthin-associated photoprotection (1993)
    Springer
    Planta 189 (1993), S. 30-38 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Desiccation tolerance ; Fluorescence quenching (non-photochemical, photochemical) ; Photoprotection ; Selaginella ; Zeaxanthin (xanthophyll cycle)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The function of photosystem (PS)II during desiccation and exposure to high photon flux density (PFD) was investigated via analysis of chlorophyll fluorescence in the desert resurrection plant Selaginella lepidophylla (Hook. and Grev.) Spring. Exposure of hydrated, physiologically competent stems to 2000 μmol · m−2 · s−1 PFD caused significant reductions in both intrinsic fluorescence yield (FO) and photochemical efficiency of PSII (FV/FM) but recovery to pre-exposure values was rapid under low PFD. Desiccation under low PFD also affected fluorescence characteristics. Both FV/FM and photochemical fluorescence quenching remained high until about 40% relative water content and both then decreased rapidly as plants approached 0% relative water content. In contrast, the maximum fluorescence yield (FM) decreased and non-photochemical fluorescence quenching increased early during desiccation. In plants dried at high PFD, the decrease in FV/FM was accentuated and FO was reduced, however, fluorescence characteristics returned to near pre-exposure values after 24-h of rehydration and recovery at low PFD. Pretreatment of stems with dithiothreitol, an inhibitor of zeaxanthin synthesis, accelerated the decline in FV/FM and significantly increased FO relative to controls at 925 μmol · m−2 · s−1 PFD, and the differences persisted over a 3-h low-PFD recovery period. Pretreatment with dithiothreitol also significantly decreased non-photochemical fluorescence quenching, increased the reduction state of QA, the primary electron acceptor of PSII, and prevented the synthesis of zeaxanthin relative to controls when stems were exposed to PFDs in excess of 250 μmol · m−2 · s−1. These results indicate that a zeaxanthin-associated mechanism of photoprotection exists in this desert pteridophyte that may help to prevent photoinhibitory damage in the fully hydrated state and which may play an additional role in protecting PSII as thylakoid membranes undergo water loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201340
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  • 6
    Electronic Resource
    Electronic Resource
    Photoacclimation and photoinhibition inUlva rotundata as influenced by nitrogen availability (1991)
    Springer
    Planta 184 (1991), S. 235-243 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Growth rate ; Nitrogen and photosynthesis ; Photoacclimation ; Photoinhibition of photosynthesis ; Photosynthesis and N supply ; Quantum yield ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clonal tissue of the marine chlorophyte macroalga,Ulva rotundata Blid., was transferred from 100 to 1700 μmol photons · m−2 · s−1 under limiting (1.5 μM NH 4 + maximum, N/P=2) and sufficient (15 μM NH 4 + maximum, N/P=20) nitrogen supply at 18° C and 11 h light-13 h darkness daily. Photoinhibition was assayed by light-response curves (photosynthetic O2 exchange), and chlorophyll fluorescence at 77 K and room temperature. Daily surface-area growth rate (μSA) in N-sufficient plants increased sixfold over 3 d and was sustained at that level. During this period, respiration (R d) doubled and light-saturated net photosynthesis capacity (P m) increased by nearly 50%, indicating acclimation to high light. Quantum yield (ϕ) decreased by 25% on the first day, but recovered completely within one week. The ratio of variable to maximum fluorescence (F v/F m) also decreased markedly on the first day, because of an increase in initial fluorescence (F o) and a decrease inF m, and partially recovered over several days. Under the added stress ofN deficiency, μSA accelerated fivefold over 4 d, despite chronic photoinhibition, then declined along with tissue-N. Respiration doubled, butP m decreased by 50% over one week, indicating inability to acclimate to high light. Bothϕ andF v/F m decreased markedly on the first day and did not significantly recover. Changes inF o,F m and xanthophyll-cycle components indicate concurrent photodamage to photosystem II (PSII) and photoprotection by thermal deexcitation in the antenna pigments. Increasing μSA coincided with photoinhibition of PSII. Insufficient diel-carbon balance because of elevatedR d and decliningP m and tissue-N, rather than photochemical damage per se, was the apparent proximate cause of decelerating growth rate and subsequent tissue degeneration under N deficiency inU. rotundata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01102423
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  • 7
    Electronic Resource
    Electronic Resource
    Fluorescence quenching during photosynthesis and photoinhibition of Ulva rotundata blid. (1993)
    Springer
    Planta 190 (1993), S. 97-106 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Photoinhibition ; Photoprotection ; Ulva (photosynthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships between photoinhibition and photoprotection in high and low-light-grown Ulva were examined by a combination of chlorophyll-fluorescence-monitoring techniques. Tissues were exposed to a computer-controlled sequence of 5-min exposures to red light, followed by 5-min darkness, with stepwise increases in photon flux. Coefficients of chlorophyll fluorescence quenching (1−qP and NPQ) were calculated following a saturating pulse of white light near the end of each 5-min light treatment. Dark-adapted chlorophyll fluorescence parameters (F0 and FV/FM) were calculated from a saturating pulse at the end of each 5-min dark period. Low-light-grown Ulva showed consistently higher 1−qP, i.e. higher reduction status of Q (high primary acceptor of photosystem II), and lower capacity for nonphotochemical quenching (NPQ) at saturating light than did high-light-grown plants. Consequently, low-light plants rapidly displayed photoinhibitory damage (increased F0) at light saturation in seawater. Removal of dissolved inorganic carbon from seawater also led to photoinhibitory damage of high-light-grown Ulva at light saturation, and addition of saturating amounts of dissolved inorganic carbon protected low-light-grown plants against photoinhibitory damage. A large part of NPQ was abolished by treatment with 3 mM dithiothreitol and the processes so inhibited were evidently photoprotective, because dithiothreitol treatment accelerated photoinhibitory damage in both low- and high-light-grown Ulva. The extent of photoinhibitory damage in Ulva was exacerbated by treatment with chloramphenicol (1 mM) without much effect on chlorophyll-quenching parameters, evidently because this inhibitor of chloroplast protein synthesis reduced the rate of repair processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195680
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  • 8
    Electronic Resource
    Electronic Resource
    Photoacclimation and photoinhibition in Ulva rotundata as influenced by nitrogen availability (1991)
    Springer
    Planta 184 (1991), S. 235-243 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Growth rate ; Nitrogen and photosynthesis ; Photoacclimation ; Photoinhibition of photosynthesis ; Photosynthesis and N supply ; Quantum yield ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clonal tissue of the marine chlorophyte macroalga, Ulva rotundata Blid., was transferred from 100 to 1700 μmol photons · m−2 · s−1 under limiting (1.5 μM NH 4 + maximum, N/P=2) and sufficient (15 μM NH 4 + maximum, N/P=20) nitrogen supply at 18° C and 11 h light-13 h darkness daily. Photoinhibition was assayed by light-response curves (photosynthetic O2 exchange), and chlorophyll fluorescence at 77 K and room temperature. Daily surface-area growth rate (μSA) in N-sufficient plants increased sixfold over 3 d and was sustained at that level. During this period, respiration (R d) doubled and light-saturated net photosynthesis capacity (P m) increased by nearly 50%, indicating acclimation to high light. Quantum yield (ϕ) decreased by 25% on the first day, but recovered completely within one week. The ratio of variable to maximum fluorescence (F v/F m) also decreased markedly on the first day, because of an increase in initial fluorescence (F o) and a decrease in F m, and partially recovered over several days. Under the added stress of N deficiency, μSA accelerated fivefold over 4 d, despite chronic photoinhibition, then declined along with tissue-N. Respiration doubled, but P m decreased by 50% over one week, indicating inability to acclimate to high light. Both ϕ and F v/F m decreased markedly on the first day and did not significantly recover. Changes in F o, F m and xanthophyll-cycle components indicate concurrent photodamage to photosystem II (PSII) and photoprotection by thermal deexcitation in the antenna pigments. Increasing μSA coincided with photoinhibition of PSII. Insufficient diel-carbon balance because of elevated R d and declining P m and tissue-N, rather than photochemical damage per se, was the apparent proximate cause of decelerating growth rate and subsequent tissue degeneration under N deficiency in U. rotundata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197952
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  • 9
    Electronic Resource
    Electronic Resource
    Photoinhibition and recovery in tropical plant species: response to disturbance (1994)
    Springer
    Oecologia 97 (1994), S. 297-307 
    Details
    ISSN: 1432-1939
    Keywords: Photoinhibition ; Rainforest disturbance Photosynthesis ; Leaf turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Disturbance or rainforest is often followed by mass mortality of understorey seedlings. Transitions of shade grown plants to full sunlight can cause reductions in the efficiency with which light is used in photosynthesis, called photoinhibition. In order to assess the influence of photoinhibition on mortality and growth after rainforest disturbance this study examined photoinhibition in both simulated and real forest disturbances in northern Papua New Guinea. In an experiment simulating rainforest disturbance, exposure of shade-grown plants to full sunlight resulted in abrupt decreases in the chlorophyll fluorescence parameter F v/F m that is characteristic of photoinhibition. However, in the well-watered plants used in these experiments there were no fatalities during 3 weeks after exposure to full sunlight. Thus, it is unlikely that photoinhibition, alone, is responsible for seedling fatalities after rainforest disturbances, but more likely that fatalities are due to photoinhibition in conjunction with other environmental stress. There were differences between the response of species to the simulated disturbance that concurred with their preferred habitats. For example, species form the genus Barringtonia, which is commonly found in shaded understorey environments, underwent greater reductions in F v/F m and were slower to recover than species that usually inhabit high solar radiation environments. The extent of photoinhibition and the rate of recovery appeared to be dependent on avoidance of direct solar radiation by altering leaf angles and on increasing maximum photosynthetic rates. A field survey of photoinhibition in man-made rainforest gaps corroborated the findings of the simulated disturbance experiment showing that plant species commonly found in shaded environments showed a greater degree of photoinhibition in forest gaps at midday than those species which are classified as species that benefit from gaps or specialist gap inhabitors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317318
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  • 10
    Electronic Resource
    Electronic Resource
    Changes of fluorescence and xanthophyll pigments during dehydration in the resurrection plantSelaginella lepidophylla in low and medium light intensities (1993)
    Springer
    Oecologia 94 (1993), S. 528-533 
    Details
    ISSN: 1432-1939
    Keywords: Fluorescence ; Photoinhibition ; Photoprotection ; Selaginella lepidophylla ; Xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The changes in photosynthetic efficiency and photosynthetic pigments during dehydration of the resurrection plantSelaginella lepidophylla (from the Chiuhahuan desert, S.W. Texas, USA) were examined under different light conditions. Changes in the photosynthetic efficiency were deduced from chlorophyll a fluorescence measurements (Fo, Fm, and Fv) and pigment changes were measured by HPLC analysis. A small decrease in Fv/Fm was seen in hydrated stems in high light (650 μmol photons·m−2·s−1) but not in low light (50 μmol photons·m−2·s−1). However, a pronounced decline in Fv/Fm was observed during dehydration in both light treatments, after one to two hours of dehydration. A rise in Fo was observed only after six to ten hours of dehydration. Concomitant with the decrease in photosynthetic efficiency during dehydration a rise in the xanthophyll zeaxanthin was observed, even in low-light treatments. The increase in zeaxanthin can be related to previously observed photoprotective non-photochemical quenching of fluorescence in dehydrating stems ofS. lepidophylla. We hypothesize that under dehydrating conditions even low light levels become excessive and zeaxanthin-related photoprotection is engaged. We speculate that these processes, as well as stem curling and self shading (Eickmeier et al. 1992), serve to minimize photoinhibitory damage toS. lepidophylla during the process of dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566968
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