Evidence for substantial variations of atmospheric hydroxyl radicals in the past two decades

The hydroxyl radical (OH) is the dominant oxidizing chemical in the atmosphere. It destroys most air pollutants and many gases involved in ozone depletion and the greenhouse effect. Global measurements of 1,1,1-trichloroethane (CH3CCl3, methyl chloroform) provide an accurate method for determining the global and hemispheric behavior of OH. Measurements show that CH3CCl3 levels rose steadily from 1978 to reach a maximum in 1992 and then decreased rapidly to levels in 2000 that were lower than the levels when measurements began in 1978. Analysis of these observations shows that global OH levels were growing between 1978 and 1988, but the growth rate was decreasing at a rate of 0.23 +/- 0.18% year(-2), so that OH levels began declining after 1988. Overall, the global average OH trend between 1978 and 2000 was -0.64 +/- 0.60% year(-1). These variations imply important and unexpected gaps in current understanding of the capability of the atmosphere to cleanse itself.

Flux-balance analysis of mitochondrial energy metabolism: consequences of systemic stoichiometric constraints

Mitochondrial metabolism is a critical component in the functioning and maintenance of cellular organs. The stoichiometry of biochemical reaction networks imposes constraints on mitochondrial function. A modeling framework, flux-balance analysis (FBA), was used to characterize the optimal flux distributions for maximal ATP production in the mitochondrion. The model predicted the expected ATP yields for glucose, lactate, and palmitate. Genetic defects that affect mitochondrial functions have been implicated in several human diseases. FBA can characterize the metabolic behavior due to genetic deletions at the metabolic level, and the effect of mutations in the tricarboxylic acid (TCA) cycle on mitochondrial ATP production was simulated. The mitochondrial ATP production is severely affected by TCA-cycle mutations. In addition, the model predicts the secretion of TCA-cycle intermediates, which is observed in clinical studies of mitochondriopathies such as those associated with fumarase deficiency. The model provides a systemic perspective to characterize the effect of stoichiometric constraints and specific metabolic fluxes on mitochondrial function.

Neighbourhood and family influences on the cognitive ability of children in the British National Child Development Study

This paper investigates the association between family poverty, the level of deprivation in electoral wards and children's cognitive test scores using data from the second generation in the 1991 sweep of the British National Child Development Study (1958 birth cohort). Family poverty has a significant association with lower test scores in children of all ages (4-18 years). Neighbourhood poverty has a significant association with lower test scores in children aged 4-5 years which, though somewhat attenuated, is independent of other socioeconomic indicators. Among children aged between 6 and 9 years, the association with neighbourhood deprivation is statistically accounted for by individual characteristics. Among children aged between 10 and 18 years, levels of neighbourhood deprivation were for the most part statistically insignificant. The family poverty--test score association among children aged between 10 and 18 years was mediated by the home environment. Mediated effects were stronger for family poverty--test score associations than for neighbourhood poverty. The use of a neighbourhood-level exposure related to the social environment leads to an understanding of the social determinants of children's outcomes that is more than the sum of individual and family-level measures. However, the size of the estimated effects of neighbourhood conditions is much smaller than the estimated effects of family-level conditions. Thus, it appears that families still should be viewed as the key agents in promoting positive development in children.

The constituents of Microctonus sp. parasitoid venoms

Purified RNA transcripts from venom glands dissected from the parasitoid wasp Microctonus hyperodae were copied, cloned and sequenced using traditional dideoxy sequencing methods. Using mass spectrometry analysis of the trypsinised PAGE gel protein bands we identified the RNA transcripts for the 3 most abundant proteins found in the venom and hence obtained their full protein sequence. Other abundant transcripts were also further sequenced. To reduce the effort required to obtain transcript information we dissected venom glands from a second parasitoid, Microctonus aethiopoides (Morocco biotype). The RNA transcripts were purified and reverse transcribed but instead of cloning the cDNA it was directly sequenced using Roche GS20 pyrosequencing. Results from a single GS20 sequencing run provided data similar to that obtained by the traditional methods used in analysing transcripts from M. hyperodae in a fraction of the time and cost. Comparing the transcripts between the two species showed that a similar range of genes are expressed with the putative orthologs of seven of the eight full length genes characterised from M. hyperodae being found in M. aethiopoides. Pyrosequencing should provide a valuable new method for rapidly sampling transcripts from a wide range of specialised insect tissues.

Model study of ATP and ADP buffering, transport of Ca(2+) and Mg(2+), and regulation of ion pumps in ventricular myocyte

We extended the model of the ventricular myocyte by Winslow et al. (Circ. Res 1999, 84:571-586) by incorporating equations for Ca(2+) and Mg(2+) buffering and transport by ATP and ADP and equations for MgATP regulation of ion transporters (Na(+)-K(+) pump, sarcolemmal and sarcoplasmic Ca(2+) pumps). The results indicate that, under normal conditions, Ca(2+) binding by low-affinity ATP and diffusion of CaATP may affect the amplitude and time course of intracellular Ca(2+) signals. The model also suggests that a fall in ATP/ADP ratio significantly reduces sarcoplasmic Ca(2+) content, increases diastolic Ca(2+), lowers systolic Ca(2+), increases Ca(2+) influx through L-type channels, and decreases the efficiency of the Na(+)/Ca(2+) exchanger in extruding Ca(2+) during periodic voltage-clamp stimulation. The analysis suggests that the most important reason for these changes during metabolic inhibition is the down-regulation of the sarcoplasmic Ca(2+)-ATPase pump by reduced diastolic MgATP levels. High Ca(2+) concentrations developed near the membrane might have a greater influence on Mg(2+), ATP, and ADP concentrations than that of the lower Ca(2+) concentrations in the bulk myoplasm. The model predictions are in general agreement with experimental observations measured under normal and pathological conditions.

Most commercial insulin assays fail to detect recombinant insulin analogues

Insulin assays are utilized in various clinical scenarios, including the assessment of insulin therapy compliance or of suspected insulin overdose. In an interpretative exercise carried out by UK National External Quality Assessment Service (NEQAS), serum sent to the participating laboratories was spiked with 30 pmol/L of the short-acting insulin analogue Human Actrapid. Only two out of 24 participant laboratories had sufficient assay cross-reactivity with Actrapid to interpret the results as suggestive of insulin administration. The development of specific insulin assays has led to deterioration in the ability to detect non-compliance or overdose with recombinant insulin treatment. Clinicians should be aware of this significant limitation, which could lead to misdiagnosis.

The social context of parenting 3-year-old children with developmental delay in the UK

BACKGROUND

Children with intellectual or developmental disability have significantly poorer health and mental health than their non-disabled peers and are at high risk of social exclusion. The aim of the present paper is to provide information on the circumstances in which 3-year-old children at risk of intellectual or developmental disability are growing up in the UK.

METHODS

Secondary analysis of data on 12 689 families in English-speaking monolingual households from the first two waves of the UK's Millennium Cohort Study. A total of 440 children (3% of the weighted sample) were identified as being developmentally delayed.

RESULTS

When compared with other children, children with developmental delays were more disadvantaged on every indicator of social and economic disadvantage examined. Two out of three children with developmental delays had been exposed to repeated disadvantage as measured by income poverty, material hardship, social housing and receipt of means-tested benefits. The effect of repeated disadvantage on the risk of developmental delay remained after account was taken of parental education and occupational status.

CONCLUSIONS

Young children with delayed development in the UK are likely to be exposed to repeated socio-economic disadvantage. Implications for policy and understanding the nature of the link between poverty and child disability are discussed.

Chloroform in the environment: occurrence, sources, sinks and effects

The chloroform flux through the environment is apparently constant at some 660+/-220 Ggyr(-1) (+/-1sigma) and about 90% of the emissions are natural in origin: the largest single source being in offshore sea water (contributing 360+/-90 Ggyr(-1)), with soil processes the next most important (220+/-100 Ggyr(-1)). Other natural sources, mainly volcanic and geological, account for less than 20 Ggyr(-1). The non-natural sources total 66+/-23 Ggyr(-1) and are much better characterised than the natural sources. They are predominantly the result of using strong oxidising agent on organic material in the presence of chloride ion, a direct parallel with the natural processes occurring in soils. Chloroform partitions preferentially into the atmosphere; the equilibrium distribution is greater than 99% and the average global atmospheric concentration has been calculated to be 18.5 pmolmol(-1). Atmospheric oxidation, the principal removal process, is approximately in balance with the identified source fluxes. Chloroform is widely dispersed in the aquatic environment (even naturally present in some mineral waters). Consequently, it is also widely dispersed in the tissue of living creatures and in foodstuffs but there is little evidence of bioaccumulation and the quantities in foodstuffs and drinking water are not problematical for human ingestion at the highest concentrations found. Definitive studies have shown that current environmental concentrations of chloroform do not present an ecotoxicological risk, even to fish at the embryonic and larval stages when they are most susceptible. By virtue of the very small amounts that actually become transported to the stratosphere, chloroform does not deplete ozone materially, nor is it a photochemically active volatile organic compound (VOC). It has a global warming potential that is less than that of the photochemically active VOCs and is not classed as a greenhouse gas.

Glucose turnover and recycling in colorectal carcinoma

Glucose metabolism is affected by various pathologic states including tumors. In this project, glucose turnover and recycling rates in 11 patients with colorectal carcinoma were measured using a double-labelled 3-3H and 1-14C glucose injection technique. Fasting blood glucose, lactate, pyruvate, alanine, glycerol, 3-hydroxybutyrate, acetoacetate, plasma cortisol, and plasma insulin concentrations were also measured. No patient in the study had a history of diabetes mellitus or endocrine disorders, nor any abnormal liver function tests. The findings demonstrated a significantly elevated glucose turnover rate in patients with Dukes C and D lesions in comparison to patients with Dukes B lesions. Cori recycling rates were not significantly different between Dukes B vs. Dukes C and D patients. There were no differences between Dukes B and Dukes C and D patients in any of the metabolites measured. Furthermore, there were no significant differences in glucose turnover or recycling rates as a function of pre-illness weight loss. These data suggest that, when colorectal carcinoma extends beyond the limits of the bowel wall, glucose metabolism is significantly altered.

Teenage childbearing in Great Britain and the spatial concentration of poverty households

STUDY OBJECTIVE

To investigate the association between the spatial concentration of deprived households and teenage non-marital childbearing. Associations with area deprivation are tested before and after allowing for levels of personal deprivation.

DESIGN AND SETTING

The individual data are derived from the 2% sample of anonymised records (SAR) from the census of 1991 in Great Britain, and are combined with area data from the 278 districts of residence identifiable in the SAR.

PARTICIPANTS

Sample is restricted to unmarried women living at home (with at least one parent) and aged 16 to 19.

MAIN RESULTS

The results suggest generally higher risk of teenage childbearing for women who are economically inactive, women from households with no access to a car or households resident in local authority accommodation. Without adjusting for personal circumstances, the risk of teenage pregnancy shows a clear, significant and approximately linear association with social deprivation of area of residence in 1991. Residual analysis shows that many urban areas have much higher levels of teenage childbearing than expected. When adjustment is made for personal disadvantage the simple association with local area deprivation is attenuated. A higher risk of teenage childbearing is still seen in urban areas while the areas having the highest negative differentials are heterogeneous.

CONCLUSIONS

Both individual and spatial characteristics are important in influencing levels of teenage childbearing. Teenage childbearing shows an association with residence in more deprived areas. The association seems to be largely because residence in more deprived areas is associated with personal disadvantage, which increases the risk of teenage childbearing. Area characteristics are of lesser significance in determining teenage non-marital childbearing than individual and household characteristics.

Trichloroacetic acid in the environment

Suppositions that the trichloroacetic acid (TCA, CCl3C(O)OH) found in nature was a consequence solely of the use of chlorinated hydrocarbon solvents prompted this critical review of the literature on its environmental fluxes and occurrences. TCA is widely distributed in forest soils (where it was rarely used as an herbicide) and measurements suggest a soil flux of 160 000 tonnes yr(-1) in European forests alone. TCA is also produced during oxidative water treatment and the global flux could amount to 55 000 tonnes yr(-1) (from pulp and paper manufacture, potable water and cooling water treatments). By contrast, the yields of TCA from chlorinated hydrocarbon solvents are small: from tetrachloroethene 13 600 tonnes yr(-1) and from 1,1,1-trichloroethane 4300 tonnes yr(-1) on a global basis, at the atmospheric burdens and removal rates typical of the late 1990s. TCA is ubiquitous in rainwater and snow. Its concentrations are highly variable and the variations cannot be connected with location or date. However, there is no significant difference between the concentrations found in Chile and in eastern Canada (by the same analysts), or between Malawi and western Canada, or between Antarctica and Switzerland, nor any significant difference globally between the concentrations in cloud, rain and snow (although local enhancement in fog water has been shown). TCA is present in old ice and firn. At the deepest levels, the firn was deposited early in the 19th century, well before the possibility of contamination by industrial production of reactive chlorine, implying a non-industrial background. This proposition is supported by plume measurements from pulp mills in Finland. TCA is ubiquitous in soils; concentrations are very variable but there are some indications that soils under coniferous trees contain higher amounts. The concentrations of TCA found in plant tissue are region-specific and may also be plant-specific, to the extent that conifers seem to contain more than other species. TCA is removed from the environment naturally. There is abundant evidence that soil microorganisms dehalogenate TCA and it is lost from within spruce needles with a half-life of 10 days. There is also recent evidence of an abiotic aqueous decarboxylation mechanism with a half-life of 22 days. The supposedly widespread effects of TCA in conifer needles are not shown in controlled experiments. At concentrations in the needles of Scots pine similar to those observed in needles in forest trees, changes consequent on TCA treatment of field laboratory specimens were almost all insignificant.

Sources of hydrochlorofluorocarbons, hydrofluorocarbons and fluorocarbons and their potential emissions during the next twenty five years

In common with CFCs, the classes of compounds in the title have wholly anthropogenic sources. CFCs are used for refrigeration, air-conditioning, foam blowing, solvent cleaning and propelling aerosols and, in each case, equipment has been designed to make the most efficient use of the properties of individual compounds. There is little scope for substitution, even between CFCs. The potential for replacement of these historic uses by substitute technologies - ammonia, hydrocarbons, carbon dioxide and HCFCs, HFCs and FCs -is examined. It is shown that the quantities required are influenced as much by improvements to containment as they are by the primary demands from society.Based on analysis of the historic data; the declared manufacturing capacities, and the anticipated effects of international controls, the potential production and emissions of the principal HCFCs and HFCs are calculated for the next twenty five years. While consumption of HCFCs will fall nearly to zero, it would appear that demand for HFC-134a could double, from approximately 150,000 to 300,000 tonnes/year between 1995 and 2020. Over the same timescale demand for HFC-32 could rise to 90,000 tonnes/year. The potential future emissions of other HCFCs, HFCs and FCs which are expected to be used less widely, or for which there is no current consumption base from which to make meaningful extrapolations, are also discussed.

Randomized controlled study of the prediction of diminutive/small colorectal polyp histology using didactic versus computer-based self-learning module in gastroenterology trainees

BACKGROUND AND AIM

The aim of this randomized trial was to evaluate the performance of self-training versus didactic training in order to increase the diagnostic accuracy of diminutive/small colonic polyp histological prediction by trainees.

METHODS

Sixteen trainees reviewed 78 videos (48 iSCAN-OE and 30 NBI) of diminutive/small polyps in a pretraining assessment. Trainees were randomized to receive computer-based self-learning (n = 8) or didactic training (n = 8) using identical teaching materials and videos. The same 78 videos, in a different randomized order, were assessed. The NICE (NBI International Colorectal Endoscopic) and SIMPLE (Simplified Identification Method for Polyp Labeling during Endoscopy) classification systems were used to classify diminutive/small polyps.

RESULTS

A higher proportion of high-confidence predictions of polyps was made by the self-training group versus the didactic group using both the SIMPLE classification (77.1% [95% CI 73.4-80.3] vs 69.9% [95% CI 66.1-73.5%] [P = 0.005]) and the NICE classification (77% [95% CI 73.2-80.4%] vs 69.8% [95% CI 66-73.4%] [P = 0.006]). When using NICE, sensitivity of the self-training group compared with the didactic group was 72% versus 83% (P = 0.0005), and the accuracy was 66.1% versus 69.1%. The training improved the confidence of participants and SIMPLE was preferred over NICE.

CONCLUSION

Self-learning for the prediction of diminutive/small polyp histology is a method of training that can achieve results similar to didactic training. Availability of adequate self-learning teaching modules could enable widespread implementation of optical diagnosis in clinical practice.

Model of the kinetics of ketone bodies in humans

The kinetics of ketone bodies was studied in normal humans by giving a combined bolus intravenous injection of labeled acetoacetate ([14C]AcAc) and D(--)-beta-hydroxybutyrate (beta-[14C]-OHB) to seven subjects after an overnight fast, on two different occasions, and by collecting frequent blood samples for 100 min. Kinetic data were analyzed with both noncompartmental and compartmental modeling techniques. A four-compartment model, representing AcAc and beta-OHB in blood and two equilibrating ketone body compartments, inside the liver and extrahepatic tissues, was chosen as the most reliable mathematical representation; it is physiologically plausible and was able to accurately fit the data. The model permitted evaluation of the in vivo rate of ketone body production in the liver, the individual plasma clearance rates of AcAc and beta-OHB, their initial volumes of distribution, and the transfer rate parameters among the four ketone body compartments. Moreover, the model provided estimates of the components of the rates of appearance of AcAc and beta-OHB in plasma due to newly synthesized ketone body from acetyl-CoA in the liver, and to interconversion and recycling in the liver and extrahepatic tissues. The model also was used to evaluate other methodologies currently employed in the analysis of ketone body turnover data: the conventional approach based on use of the combined specific activity of AcAc and beta-OHB required assumptions not satisfied in vivo, leading to substantial errors in key parameter estimates.

Quantitative adjustment for macroprolactin is an integral part of laboratory assessment of hyperprolactinaemia

INTRODUCTION

Prolactin circulates predominantly as a 23-kDa monomer, and a high-molecular-weight form largely consisting of a complex of prolactin and an anti-prolactin IgG autoantibody, called macroprolactin. This cross-reacts with conventional laboratory assays for prolactin. We here describe how quantitative adjustment for this may assist patient management.In a consecutive series of 218 patients with prolactin elevated to 400 mu/L or more in men (normal range ≤ 180) (n=79, 36.2% of sample) and 1 000 mu/L or more in women (normal range ≤ 500) (n=139, 63.8%) a macroprolactin screen was performed using PEG precipitation.

RESULTS

Where present, median macroprolactin as a proportion of total prolactin was in women 13% (percentile 25-percentile 75: 7-25%) and in men 15% (7-30%).The distribution of macroprolactin as a proportion of total prolactin was markedly skewed to the left with 69.7% of women and 62.9% of men having macroprolactin proportion of 20% or less. There was no relation between %macroprolactin and total measured prolactin, age or gender.Of relevance to clinical management, in 24% of men and 20.5% of women, correction for estimated macroprolactin gave an adjusted monomeric prolactin level below the agreed threshold for further investigation, potentially avoiding unnecessarily referral.In our clinical series, quotation of an adjusted monomeric prolactin would have resulted in unnecessary further investigation being avoided in a number of cases.

DISCUSSION

Screening for macroprolactin is a key element of laboratory assessment for hyperprolactinaemia.In cases where measured total prolactin is significantly raised, quantitative reporting of estimated monomeric prolactin instead of just 'macroprolactin' positive' can avoid unnecessary investigations.

Spanish and Catalan translation, cultural adaptation and validation of the Picker Patient Experience Questionnaire-15

OBJECTIVE

To develop and test a culturally adapted core set of questions to measure patients' experience after in-patient care.

MATERIAL AND METHODS

Following the methodology recommended by international guides, a basic set of patient experience questions, selected from Picker Institute Europe questionnaires (originally in English), was translated to Spanish and Catalan. Acceptability, construct validity and reliability of the adapted questionnaire were assessed via a cross-sectional validation study. The inclusion criteria were patients aged >18 years, discharged within one week to one month prior to questionnaire sending and whose email was available. Day cases, emergency department patients and deaths were excluded. Invitations were sent by email (N=876) and questionnaire was fulfilled through an online platform. An automatic reminder was sent 5 days later to non-respondents.

RESULTS

A questionnaire, in Spanish and Catalan, with adequate conceptual and linguistic equivalence was obtained. Response rate was 44.4% (389 responses). The correlation matrix was factorable. Four factors were extracted with Parallel Analysis, which explained 43% of the total variance. First factor: information and communication received during discharge. Second factor: low sensitivity attitudes of professionals. Third factor: assessment of communication of medical and nursing staff. Fourth factor: global items. The value of the Cronbach alpha was 0.84, showing a high internal consistency.

CONCLUSIONS

The obtained experience patient questionnaire, in Spanish and Catalan, shows good results in the psychometric properties evaluated and could be a useful tool to identify opportunities for health care improvement in our context. Email could become a feasible tool for greater patient participation in everything that concerns his health.

Some hormonal influences on glucose and ketone body metabolism in normal human subjects

Control of glucose and ketone body metabolism is integrated by a variety of hormones. Insulin is the major anabolic hormone, and its actions are antagonized by rapidly acting catabolic hormones, such as glucagon and the catecholamines, and by others such as cortisol, growth hormone and the thyroid hormones, which generally have more delayed effects. In the normal human subject, the effects of catabolic hormones to raise blood glucose are limited by a compensatory increase in insulin secretion, and these effects are enhanced in insulin deficiency. Hyperketonaemic actions of the catabolic hormones may result from increased supply of non-esterified fatty acids from lipolysis, although glucagon has a major direct action to increase ketogenesis at the liver. As expected, these actions are also restricted in normal humans by the compensatory rise in insulin secretion. Hyperketonaemia does, however, occur with adrenaline (epinephrine) and noradrenaline (norepinephrine), even in the presence of mildly elevated insulin concentrations. These catecholamines may assume particular importance in mobilization of lipid fuels in milder forms of stress, when insulin secretion is normal or mildly increased. In severe stress, when there is catecholamine-induced suppression in insulin secretion, lipolytic and hyperketonaemic effects of all the catabolic hormones may be manifest. Starvation in humans also results in diminished insulin secretion and increased catabolic hormone secretion. The relative importance of individual hormones in lipid mobilization during starvation is uncertain, although glucagon, growth hormone, noradrenaline and, possibly, dopamine may all play a part.

The addition of insulin to home parenteral nutrition for the control of hyperglycaemia: A case series

There is little data on the safety or efficacy of insulin added to parenteral nutrition in the homecare setting. We report the use of this route of insulin administration in a series of 4 patients spanning 39 patient years in which it appeared effective, safe and well tolerated.

Metabolism of inositol 1- and 4-monophosphates in HL60 promyelocytic leukaemia cells

The metabolism of inositol 1- and 4-monophosphates in HL60 promyelocytic leukaemia cells was studied. LiCl, BeCl2 and NaF inhibited the hydrolysis of both monophosphates with half maximal inhibition occurring at 1.2 mM, 0.3 microM, 0.25 mM (Ins 1P) and 0.14 mM, 0.56 microM, 0.28 mM (Ins 4P) respectively. Lithium was an uncompetitive inhibitor with respect to both substrates. Ins 4P inhibited the hydrolysis of Ins 1P in a concentration dependent manner, suggesting that it acts as a competing substrate for the same enzyme. Half maximal inhibition occurred at 120 microM Ins 4P. The lithium sensitive activity responsible for the metabolism of both monophosphates was present in a soluble fraction made from the cells. Taken together these data suggest that Ins 1P and Ins 4P are hydrolysed by a single soluble enzyme activity which is sensitive to inhibition by lithium, beryllium and fluoride.