A cephalometric study in Rubinstein-Taybi syndrome

A roentgencephalometric study to compare the facial morphology of 18 individuals affected with Rubinstein-Taybi syndrome and 25 of their parents was performed. The main findings in the affected individuals were shortening of facial height and depth, cranial base length, a marked decrease in size of the mandible, and a steep cranial base. A change with age was found for some dimensions. The pattern variability indices were high, indicating an abnormal craniofacial profile. The correlations between most patients were high, although this was less expressed for the younger patients. The parents had a normal pattern profile and pattern profile variability indices. The correlation between parents and their affected children was low. This study suggests that pattern profile analysis of cephalometric measurements may be a useful diagnostic tool in Rubinstein-Taybi syndrome. However, comparable studies of large groups of patients, especially of a younger age, are needed for further ascertainment of normal values in individuals with Rubinstein-Taybi syndrome at different stages of facial development.     

Relative growth rate, biomass allocation pattern and water use efficiency of three wheat cultivars during early ontogeny as dependent on water availability

We have investigated the water use efficiency of whole plants and selected leaves and allocation patterns of three wheat cultivars (Mexipak, Nesser and Katya) to explore how variation in these traits can contribute to the ability to grow in dry environments. The cultivars exhibited considerable differences in biomass allocation and water use efficiency. Cultivars with higher growth rates of roots and higher proportions of biomass in roots (Nesser and Katya) also had higher leaf growth rates, higher proportions of their biomass as leaves and higher leaf area ratios. These same cultivars had lower rates of transpiration per unit leaf area or unit root weight and higher biomass production per unit water use. They also had higher ratios of photosynthesis to transpiration, and lower ratios of intercellular to external CO₂ partial pressure. The latter resulted from large differences in stomatal conductance associated with relatively small differences in rates of photosynthesis. There was little variation between cultivars in response to drought, and differences in allocation pattern and plant water use efficiency between cultivars as found under well-watered conditions persisted under dry conditions. At the end of the non-watered treatment, relative growth rates and transpiration rates decreased to similar values for all cultivars. High ratios of photosynthesis to transpiration, and accordingly high biomass production per unit of transpiration, is regarded as a favourable trait for dry environments, since more efficient use of water postpones the decrease in plant water status.     

Development of a competitive immunoassay for the determination of N-(2-hydroxypropyl)valine adducts in human haemoglobin and its application in biological monitoring

Abstract

Propylene oxide (PO) is an important industrial compound and a directly acting mutagen. Human exposure to PO can be monitored by the determination of haemoglobin adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxypropyl)valine in whole haemoglobin was developed and its potential usefulness as a tool for biologically monitoring occupational exposure was demonstrated. Analytical reliability was confirmed in a comparative study with GC-MS (range 3.7–992 nmol g^?1 haemoglobin (Hb), correlation coefficient 0.99, n=10). The assay has been configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay employs a whole blood matrix and has a working range of 2–250 pmol g^?1 Hb. It does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results in potentially exposed workers indicate the assay's high potential usefulness in routine occupational biomonitoring of exposure to PO.     

Contrasting effects of N and P deprivation on the regulation of photosynthesis in tomato plants in relation to feedback limitation

The effects were studied of both nitrogen and phosphorus limitation and irradiance on the performance and operation of photosynthesis in tomato leaves (Lycopersicon esculentum Mill.). Plants were grown at low N, high N, low P or high P supply and at two irradiances. Using mature leaves, measurements were made of the irradiance dependencies of the relative quantum efficiencies of photosystems I and II, and of the rate of carbon dioxide fixation. Measurements were also made of foliar starch and chlorophyll concentrations. The results showed that photosynthetic light-harvesting and electron-transport activity acclimate to nutrient stress and growth irradiance such that the internal relationships between electron transport by photosystems I and II do not change; the linear relationship between PhiPSII, and PhiPSI was not affected. It was also evident that under N stress photosynthesis was reduced by a decreased light absorption and by the decreased utilization of assimilates, while P stress mainly affected the carboxylation capacity. Under N stress foliar starch levels increased and the oxygen sensitivity of CO2 fixation decreased, whereas P stress resulted in decreased starch levels and increased oxygen sensitivity of CO2 fixation. The relationship between starch accumulation and oxygen sensitivity (increased starch correlated with decreased oxygen sensitivity) was always the same across the nutrient treatments. These results are consistent with N deprivation producing an increasing limitation of photosynthesis, possibly by feedback from the leaf carbohydrate pool, whereas, although P deprivation produces a decreased rate of CO2 fixation, this is accompanied by a increase in oxygen sensitivity, suggesting that feedback limitation is decreased under P stress.     

Use of haemoglobin adducts in exposure monitoring and risk assessment

Many industrial bulk chemicals are oxiranes or alkenes that are easily metabolised to oxiranes in mammalian systems. Many oxiranes may react with DNA and are therefore mutagenic in vitro. Some oxiranes have been shown to be carcinogenic in rodents in vivo as well. Despite the very limited evidence of the carcinogenicity of oxiranes in humans, they should be considered potential human carcinogens. As a consequence, exposure to these compounds should be minimised and controlled. Twenty-five years ago, Ehrenberg and co-workers suggested that exposure to oxiranes might be determined through the measurement of the adducts they form with haemoglobin (Hb). Ten years later, a modification of the Edman degradation was developed at Stockholm University that allowed determination of adducts with the N-terminal valine of Hb by GC-MS. In our laboratory, this methodology was modified and adapted for analysis on an industrial scale. Since 1987, exposure of operators in our facilities to ethylene oxide (EO) has been routinely monitored by determination of N-(2-hydroxyethyl)valine in Hb. Biological monitoring programmes for propylene oxide (PO) and 1,3-butadiene (BD) were developed later. In this review, the methodology and its results are discussed as a tool in human risk assessment of industrial chemicals. Two major advantages of Hb adduct determinations in risk assessment are (1) the qualitative information on the structure of reactive intermediates that may be obtained through the mass spectrometry, which may provide insight in the molecular toxicology of compounds such as BD, and (2) the possibility of reliable determination of exposure over periods of several months with limited number of samples for compounds such as ethylene oxide (EO), propylene oxide (PO) and BD which form stable adducts with Hb. Since good correlations between the airborne concentrations of these chemicals with their respective adducts have been established, Hb adducts can also be used to quantitate airborne exposure which is of paramount importance as exposure assessment is usually one of the weaker parameters in risk assessment.     

Regeneration experiments of the platinated enzyme fumarase, using sodium diethyldithiocarbamate, thiourea, and sodium thiosulfate.

The enzyme fumarase is inhibited by [cis-Pt(NH3)2(H2O)2] (NO3)2. The Pt compound most likely binds at a S-methionine site. Sodium diethyldithiocarbamate (Naddtc) appears to be a powerful regenerator of enzymatic activity. Thiourea is less active, while sodium thiosulfate (STS) is almost inactive in restoring the activity of the enzyme. The regeneration phenomena are based on the dissociation of the Pt-S bonds of the methionine type, and formation of species like [Pt(ddtc)2]. In the model adduct [Pt(dien)GS-Me]2+ Naddtc, thiourea and STS easily break the Pt-S bond of the methionine type. It is concluded that the model system for Naddtc and thiourea does resemble fumarase quite well. S-donor ligands, which may be used as rescue agents in Pt antitumor therapy, are known to suppress nephrotoxicity caused by [cis-PtCl2(NH3)2]. A parallel is drawn between the enzyme reactivation, modeled by fumarase, and the [cis-PtCl2(NH3)2] nephrotoxicity suppression by rescue agents. It is proposed that a Pt-methionine type binding is broken by the rescue agents Naddtc and thiourea, but that the rescue agent STS only inhibits the nephrotoxicity by inactivating unbound Pt species in the cell.     

The sociocultural sustainability of livestock farming: an inquiry into social perceptions of dairy farming

Over the past 50 years, the scale and intensity of livestock farming have increased significantly. At the same time, Western societies have become more urbanised and fewer people have close relatives involved in farming. As a result, most citizens have little knowledge or direct experience of what farming entails. In addition, more people are expressing concerns over issues such as farm animal welfare. This has led to increasing public demand for more sustainable ways of livestock farming. To date, little research has been carried out on the social pillar of sustainable livestock farming. The aim of this study is to provide insights into the sociocultural sustainability of livestock farming systems. This study reviews the key findings of earlier published interdisciplinary research about the social perceptions of dairy farming in the Netherlands and Norway (Boogaard et al., 2006, 2008, 2010a and 2010b) and synthesises the implications for sociocultural sustainability of livestock farming. This study argues that the (sociocultural) sustainable development of livestock farming is not an objective concept, but that it is socially and culturally constructed by people in specific contexts. It explains the social pillar of the economics/ecological/social model sustainability in terms of the fields of tensions that exist between modernity, traditions and naturality - 'the MTN knot' - each of which has positive and negative faces. All three angles of vision can be seen in people's attitudes to dairy farming, but the weight given to each differs between individuals and cultures. Hence, sociocultural sustainability is context dependent and needs to be evaluated according to its local meaning. Moreover, sociocultural sustainability is about people's perceptions of livestock farming. Lay people might perceive livestock farming differently and ascribe different meanings to it than experts do, but their 'reality' is just as real. Finally, this study calls for an ongoing collaboration between social and animal scientists in order to develop livestock farming systems that are more socioculturally sustainable.     

Development of a competitive immunoassay for the determination of N-(2-hydroxyethyl)valine adducts in human haemoglobin and its application in biological monitoring

Ethylene oxide (EO) is an important industrial compound and a directly acting mutagen. Human exposure to it can be monitored by the determination of haemoglobin (Hb) adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxyethyl)valine in whole blood was developed and its potential usefulness as a tool for biologically monitoring occupational exposure demonstrated. Analytical reliability was confirmed in a comparative study with gas chromatography-mass spectrometry (range 0.040-589 nmol g^-1 Hb, correlation coefficient 0.98, n=10). The assay was configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay uses a whole blood matrix and has a working range of 10-10 000 pmol N-(2-hydroxethyl)valine g^-1 Hb. The assay does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results from potentially exposed workers indicate the assay might be a powerful tool for the routine occupational biomonitoring of EO exposure.     

Interaction of nitrogen and phosphorus nutrition in determining growth

In this paper we discuss the differences and similarities in the growth response of tomato plants to N and P limitation, and to their interaction. Two detailed growth experiments, with varied N or P supply, were conducted in order to unravel the effects of N and P limitation on growth of young tomato plants (Lycopersicon esculentum Mill.). Relative growth rate (RGR) initially increased sharply with increasing plant P concentration but leveled off at higher plant P concentrations. In contrast, RGR increased gradually with increasing plant N concentration before it leveled off at higher plant N concentrations. The relationship of RGR with organic leaf N and P showed the same shape as with total N and P concentrations, respectively. The difference in response is most likely due to the different roles of N and P in the machinery of the plant's energy metabolism (e.g., photosynthesis, respiration). Plant N concentration decreased with increasing P limitation. We show that this decrease cannot be explained by a shift in dry-mass partitioning. Our results suggest that the decrease in N concentration with increasing P limitation may be mediated by a decrease in leaf cytokinin levels and is less likely due to decreased energy availability at low P conditions. Dry-mass partitioning to the roots was closely linearly related to the leaf reduced-N concentration. However, treatments that were severely P limited deviated from this relationship.