Multivitamin and mineral use and breast cancer mortality in older women with invasive breast cancer in the women's health initiative.

Multivitamin use is common in the United States. It is not known whether multivitamins with minerals supplements (MVM) used by women already diagnosed with invasive breast cancer would affect their breast cancer mortality risk. To determine prospectively the effects of MVM use on breast cancer mortality in postmenopausal women diagnosed with invasive breast cancer, a prospective cohort study was conducted of 7,728 women aged 50-79 at enrollment in the women's health initiative (WHI) in 40 clinical sites across the United States diagnosed with incident invasive breast cancer during WHI and followed for a mean of 7.1 years after breast cancer diagnosis. Use of MVM supplements was assessed at WHI baseline visit and at visit closest to breast cancer diagnosis, obtained from vitamin pill bottles brought to clinic visit. Outcome was breast cancer mortality. Hazard ratios and 95 % confidence intervals (CIs) for breast cancer mortality comparing MVM users to non-users were estimated using Cox proportional hazard regression models. Analyses using propensity to take MVM were done to adjust for potential differences in characteristics of MVM users versus non-users. At baseline, 37.8 % of women reported MVM use. After mean post-diagnosis follow-up of 7.1 ± 4.1 (SD) years, there were 518 (6.7 %) deaths from breast cancer. In adjusted analyses, breast cancer mortality was 30 % lower in MVM users as compared to non-users (HR = 0.70; 95 % CI 0.55, 0.91). This association was highly robust and persisted after multiple adjustments for potential confounding variables and in propensity score matched analysis (HR = 0.76; 95 % CI 0.60-0.96). Postmenopausal women with invasive breast cancer using MVM had lower breast cancer mortality than non-users. The results suggest a possible role for daily MVM use in attenuating breast cancer mortality in women with invasive breast cancer but the findings require confirmation.

Cytotoxic activity of extracts from Hypochaeris radicata.

Pasture-associated stringhalt is an acquired equine disease characterized by peripheral neuropathy and hyperflexion of the pelvic limbs. The disease occurs most commonly during periods of drought in horses grazing pastures heavily contaminated by Hypochaeris radicata. We hypothesized that stringhalt is caused by neurotoxins elaborated by H. radicata in response to the stress of drought conditions. Supernates were collected from H. radicata that were stressed (or not) by immersion in copper chloride solution, then extracted with ethyl acetate and dried. Dilutions of extracts from stressed (SE) and control, unstressed (UE) plants were incubated with myelinating spinal cord cultures (MSCC) established from fetal Swiss mice, and with spinal ganglion cultures (SGC) and dermal fibroblast cultures derived from neonatal mouse tissues. Cytotoxicity in culture monolayers was evaluated both morphologically by microscopy and by release of lactate dehydrogenase activity into culture supernates. Three different SGC preparations were exposed to a single H. radicata extract and single preparations of fibroblasts and MSCC were exposed to three different extracts. Repin, a plant-derived sesquiterpene lactone neurotoxin, was included as a positive control. Significant dose-dependent cytotoxicity was seen within 24 h in all three culture types when incubated with SE or repin. Complete morphologic destruction of culture monolayers was induced by the highest concentrations tested of SE (100 µg/mL) and repin (30 µg/mL). Cytotoxic effect of SE was significantly greater than that of UE for all three cell types and was not due to copper contamination of the extract. This study has identified a cytotoxic activity in leaf exudates of H. radicata that was upregulated by the model stressor, copper chloride.

Selenium status and allergic disease in a cohort of New Zealand children.

BACKGROUND: New Zealand has one of the highest rates of asthma and atopy. Selenium has been implicated in the aetiology of asthma, and associations between low selenium status and asthma in New Zealand children have been reported. OBJECTIVE: The aim was to investigate the association between selenium status and allergic disease in a birth cohort of New Zealand children. METHODS: The New Zealand Asthma and Allergy Cohort Study is a prospective birth cohort in Wellington and Christchurch, involving 1105 infants born 1997-2001. During the 6-year assessment (n = 635), associations were investigated between plasma selenium (PlSe) and whole blood glutathione peroxidase activity (WBGPx) and allergy-related health outcomes including asthma, wheeze, hayfever, rhinitis, eczema and rash. RESULTS: Wellington children had greater PlSe and WBGPx than Christchurch children (P < 0.001 for both). PlSe (P = 0.004) and WBGPx (P = 0.03) were lower in children exposed to environmental smoke, but differences were no longer significant after adjustment for study location, current household smoking (5-6 years), maternal smoking during pregnancy, family history (either parent with asthma, eczema or hayfever), prioritized ethnicity (Maori, Pacific peoples, Other, European), gender, season born, number of siblings, New Zealand Deprivation Index and body mass index at 6 years. Analysis of PlSe or WBGPx as continuous variables or of quartiles of PlSe with health outcomes showed no significant associations after adjustment. Univariate analysis of quartiles of PlSe and WBGPx with persistent wheeze showed significant inverse trends (P = 0.005 for both), but these reduced after adjustment. CONCLUSIONS AND CLINICAL RELEVANCE: Our results do not support a strong association between selenium status and the high incidence of asthma in New Zealand. However, there was a modest association between lower PlSe and WBGPx activity and higher incidence of persistent wheeze.

An optimized method to assess in vivo efficacy of antithrombotic drugs using optical coherence tomography and a modified Doppler flow system.

INTRODUCTION: Animal models of venous and arterial thrombosis are extremely useful to study the efficacy of antithrombotic agents. Variability in efficacy data is often observed in those preclinical studies. The goal of this study was to optimize the methodology for assessing antithrombotic drug efficacy by the use of optical coherence tomography (OCT) and a modified Doppler flow system in rat models of thrombosis. METHODS: Thrombus formation was assessed in both the rat venous and arterial ferric chloride (FeCl(3)) models of thrombosis. In the venous model, thrombus volume post-treatment was measured using OCT, and data were correlated against the thrombus weight. In the arterial model, the time to occlusion was measured using a Doppler flow probe connected to a perivascular flow module which allowed the reporting of dynamic blood flow data every 30s. Heparin (130 or 165U/kg), argatroban (4.5mg/kg), bivalirudin (1.3mg/kg) or saline were administered intravenously. RESULTS: In the venous model, for all treatment groups a strong linear correlation (R(2)=0.998) was observed between thrombus volume measured by OCT and thrombus weight. In the arterial model, using a high sampling rate of a dynamic blood flow using a modified Doppler flow system provided data accuracy and precision of the time to occlusion measurement. DISCUSSION: This study demonstrates that OCT is a powerful tool for the assessment of antithrombotic drug efficacy. Furthermore, it shows that a high Doppler sampling rates of dynamic blood flow leads to data accuracy and precision.

Vitamin D: the light side of sunshine.

Under normal circumstances, vitamin D is mainly obtained from skin through the action of ultraviolet B irradiation on 7-dehydrocholesterol. It is further metabolized to 25-hydroxyvitamin D (25OHD), the major circulating vitamin D compound, and then to 1,25-dihydroxyvitamin D, the hormonal form. The major function of vitamin D compounds is to enhance active absorption of ingested calcium (and phosphate). This assists in building bone at younger ages and ensures that despite obligatory urinary losses, bone does not need to be resorbed to maintain blood calcium concentrations. Vitamin D compounds appear to have direct effects to improve bone and muscle function, and there is good, although not entirely consistent, evidence that supplemental vitamin D and calcium together reduce falls and fractures in older individuals. On the basis of calcium control and musculoskeletal function, target levels for 25OHD in blood are at least 50-60 nmol/l and there may be a case for higher targets of 75-80 nmol/l. There are vitamin D receptors in most nucleated cells and some evidence, although not consistent, that adequate vitamin D levels may be important in reducing the incidence of, or mortality from, some cancers and in reducing autoimmune disease. Adequate vitamin D may also allow for a normal innate immune response to pathogens, improve cardiovascular function and mortality and increase insulin responsiveness. Vitamin D levels are maintained better in the presence of adequate calcium intakes, more exercise and less obesity. Genetic variation may have an effect on vitamin D blood levels and response to treatment with vitamin D.

Green tea improves metabolic biomarkers, not weight or body composition: a pilot study in overweight breast cancer survivors.

BACKGROUND: Overweight status after breast cancer treatment may increase a woman's risk for recurrent disease and/or early onset cardiovascular disease. Green tea has been proposed to promote weight loss and favourably modify glucose, insulin and blood lipids. This pilot study tested the effect of daily decaffeinated green tea consumption for 6 months on weight and body composition, select metabolic parameters and lipid profiles in overweight breast cancer survivors. METHODS: The effect of daily decaffeinated green tea intake on weight, body composition and changes in resting metabolic rate, energy intake, glucose, insulin, homeostasis model assessment--insulin resistance (HOMA-IR) and lipids was evaluated in overweight breast cancer survivors. Participants had a mean weight of 80.2 kg; body mass index (BMI) 30.1 kg m⁻²; and body fat 46.4%. Participants (n = 54) were randomised to 960 mL of decaffeinated green or placebo tea daily for 6 months. RESULTS: Mean (SD) tea intake among study completers (n = 39) was 5952 (1176) mL week⁻¹ and was associated with a significant reduction in energy intake (P = 0.02). Change in body weight of -1.2 kg (green tea) versus +0.2 kg (placebo) suggests a weight change effect, although this was not statistically significant. Decaffeinated green tea intake was associated with elevated high-density lipoprotein (HDL) levels (P = 0.003) and nonsignificant improvements in the HDL/LDL ratio and HOMA-IR (-1.1 ± 5.9: green tea; +3.2 ± 7.2: herbal). CONCLUSIONS: Intake of decaffeinated green tea for 6 months was associated with a slight reduction in body weight and improved HDL and glucose homeostasis in overweight breast cancer survivors.

Assessment of requirements for selenium and adequacy of selenium status: a review.

OBJECTIVE: The intent of this review is to evaluate the scientific evidence for the assessment of adequacy of selenium status and of the requirements for selenium. From this evidence, attempts have been made to define levels of plasma selenium and dietary selenium intake, which could be used for the assessment of deficiency or adequacy of selenium status. METHOD: The first section briefly reviews the methods for assessment of selenium status. The second section outlines the requirements for selenium based on a number of criteria, and how these have been translated into recommended intakes of selenium. In the final section, levels of plasma selenium and dietary intake based on different criteria of adequacy have been proposed. RESULTS AND CONCLUSION: The minimum requirement for selenium is that which prevents the deficiency disease, Keshan disease. The recommended intakes of selenium have been calculated from the requirement for optimum plasma glutathione peroxidase (GPx) activity that must, because of the hierarchy of selenoproteins, also take account of the amounts needed for normal levels of other biologically necessary selenium compounds. Whether optimal health depends upon maximization of GPx or other selenoproteins, however, has yet to be resolved, and the consequences of less-than-maximal GPx activities or mRNA levels need investigation. Intakes, higher than recommended intakes, and plasma selenium concentrations that might be protective for cancer or result in other additional health benefits have been proposed. There is an urgent need for more large-scale trials to assess any such beneficial effects and to provide further data on which to base more reliable estimates for intakes and plasma selenium levels that are protective.

Ecological condition of central Australian arid-zone rivers.

Australian arid-zone rivers are known to be ecologically variable and go through "boom and bust" cycles based on highly variable and unpredictable flow regimes. They are facing increasing pressure from land and water resources development and, whilst they are considered to be still in relatively good condition, no studies have yet been carried out to verify this. Such baseline studies are crucial if we are to assess any ecological changes in response to development and management interventions. The ecological condition of four of these endorheic rivers (Georgina, Diamantina, Cooper-Thomson and Bulloo) flowing into the Lake Eyre and Bulloo Basins in central Australia was assessed using several criteria (level of human influence, habitat condition, water chemistry and aquatic macroinvertebrate composition). Using criteria based on the level of human influence, most of the sites were assessed to be relatively unimpacted (reference) condition. The most discernible and widespread impact was riparian and bank damage by stock access. However, the level of this impact was considered to be only moderate. Most aquatic macroinvertebrates found in the area are considered to be opportunistic and tolerant of a wide range of environmental conditions, but with their life histories known to be linked to flow conditions. Their trophic guild was dominated by collectors and predators. The AusRivAS modelled observed to expected values of macroinvertebrate composition indicated that there were differences in ecological condition between sites (e.g. different waterholes) and between times (e.g. seasons and years). Overall, 75% of sites were assessed to be good condition with the remainder being mildly impaired. Water chemistry of the sites was characterised by high spatial and temporal variability with low conductivity and alkaline pH, relatively high turbidity, total nitrogen and total phosphorus, and wide-ranging dissolved oxygen. Given the high variability in water quality and ecological condition within a catchment, there was little evidence of any overall difference in these factors between the catchments. However, given that the hydrology of each river system is distinctly different, one might expect some differences in ecological structure and function at finer scale. Periods of hydrological isolation (eg. to allow natural dryouts) as well as the maintenance of natural connectivity (eg. instream, overbank and floodplain wetting) are both necessary for the maintenance of ecological integrity of these systems.

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study.

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.

Urinary selenium and iodine during pregnancy and lactation.

The New Zealand environment is low in selenium and iodine, and is therefore ideally suited for the study of these anionic trace elements. The aim of this study was to determine urinary excretion of selenium and iodine during pregnancy and postpartum as part of an investigation of the influence of pregnancy and lactation on selenium metabolism in women of low selenium status. In a double-blind placebo-controlled study, 35 women in the earliest stages of pregnancy and 17 non-pregnant women were recruited in Dunedin, New Zealand. Eighteen pregnant women received 50 microg selenium as L-selenomethionine, while the others received a placebo daily during pregnancy and 12 months postpartum. The non-pregnant women received the supplement, serving as a positive control. Blood samples and twenty-four hour urine samples were collected monthly during pregnancy and at 3, 6, and 12 months postpartum for analysis of selenium and iodine. Selenium content in plasma and urinary excretion of selenium fell during pregnancy; however, total excretion of selenium was greater during pregnancy than postpartum. Urinary iodine excretion was much lower than reported previously in New Zealand. Due to large intra- and inter-subject variability, no trends in iodide excretion were observed. Factors which influence urinary excretion of selenium include dietary intake, but more closely, plasma concentrations of selenium (which is probably related to total selenium pool), creatinine excretion and therefore lean body mass, and glomerular filtration rate. The exact mechanism and sequence of events remains unclear and future studies incorporating new speciation techniques are necessary.

Lower proportion of CD45R0+ cells and deficient interleukin-10 production by formula-fed infants, compared with human-fed, is corrected with supplementation of long-chain polyunsaturated fatty acids.

BACKGROUND: The immune consequences of adding 20:4n-6 and 22:6n-3 fatty acids to preterm infant formula are not known. METHODS: The effect of feeding preterm infants (14-42 days of age) human milk (Human Milk group), infant formula (Formula group), or formula with added long-chain polyunsaturated fatty acids 20:4n-6 and 22:6n-3 (Formula + LCP group) on isolated peripheral blood lymphocytes (by flow cytometry) and lipid composition (by gas-liquid chromatography) was determined. Lymphocytes were stimulated in vitro with phytohemagglutinin to measure soluble interleukin (sIL)-2R and IL-10 production (by enzyme-linked immunosorbent assay). RESULTS: With age, the percentage of CD3+ CD4+ T cells and the percentage of CD20+ cells increased in the Human Milk and Formula + LCP groups (P < 0.05), but not in the unsupplemented Formula group. Compared with the Formula group, CD4+ cells from the Formula + LCP and Human Milk groups expressed more CD45R0 (antigen mature) and less CD45RA (antigen naive) at 42 days of age (P < 0.05). At 42 days, IL-10 production was lower (P < 0.05) in cells of the Formula group than in cells of the Human Milk group. Production of IL-10 by the cells of the Formula + LCP group was not different from that produced by the Human Milk group cells. An age-related decrease (P < 0.05) in sIL-2R production by Formula + LCP lymphocytes was observed, but sIL-2R production at 42 days in the Formula + LCP group did not differ significantly from that in the Human Milk group. Compared with Formula alone, adding LCP to formula resulted in a lower C18:2n-6 and higher C20:4n-6 content in lymphocyte phospholipids (P < 0.05). CONCLUSIONS: Adding LCP to a preterm infant formula resulted in lymphocyte populations, phospholipid composition, cytokine production, and antigen maturity that are more consistent with that in human milk-fed infants. This may affect the ability of the infant to respond to immune challenges.

The use of a hydrophobic matrix for the sustained release of a highly water soluble drug.

An experimental investigation into the use of a hydrophobic matrix to control the release of a highly water soluble drug was undertaken. Matrices consisting of hydrogenated vegetable oil and calcium sulfate with a 4% drug loading showed a sustained-release profile of up to 24 hr. The release mechanism from such matrices seemed to obey both root time kinetics and first-order behavior. Investigations showed that the effect of geometry had a significant effect on the drug release rate.

An estimation of selenium requirements for New Zealanders.

BACKGROUND: Current US dietary recommendations for selenium are based on maximization of plasma glutathione peroxidase (GSHPx) activity according to data from one study of Chinese men. OBJECTIVE: The effect of various amounts of supplemental selenium on GSHPx activities in blood of New Zealand adults was investigated to calculate a selenium requirement for New Zealanders. The effect on plasma selenoprotein P and thyroid hormones was also investigated. DESIGN: Fifty-two adults with low blood selenium concentrations ingested a placebo or 10, 20, 30, or 40 microgram Se as L-selenomethionine daily for 20 wk. RESULTS: Plasma and whole-blood GSHPx activities increased in all supplemented groups but reached a plateau only in the group receiving 40 microgram Se, as determined by statistical analysis. Increases in selenoprotein P were greater than those for selenium and GSHPx at all supplement intakes. Thyroxine concentrations decreased in supplemented groups but the decrease was significantly different from that in the control group only for the 10-microgram group and for all supplemented groups combined. CONCLUSIONS: An upper estimated requirement of 90 microgram Se/d was calculated as the intake necessary for maximization of plasma GSHPx activity, as used in the derivation of the US recommended daily allowance. Our lower estimated requirement of 39 microgram Se/d was the intake necessary to reach two-thirds of maximal GSHPx activity, as was used in calculating the World Health Organization normative requirement. The lower estimate is a realistic goal for New Zealand but the upper estimate could be achieved only with regular inclusion of high-selenium foods.

Selenium supplementation affects the retention of stable isotopes of selenium in human subjects consuming diets low in selenium.

Twenty-nine women and fifteen men from an area of low Se intake (South Island of New Zealand) consumed 100 micrograms stable 74Se, as selenate given in water after an overnight fast, and blood was collected for 3 weeks. They were then divided into five groups and supplemented with 0, 10, 20, 30 and 40 micrograms Se/d (as selenomethionine) for 5 months. After 5 months, they received a second dose of 74Se identical to the first. Supplementation significantly altered retention of 74Se in the plasma, but not in the erythrocytes or platelets. Subjects receiving the placebo retained the greatest amount, and subjects receiving 30 micrograms supplemental Se/d retained the least 74Se. Supplementation resulted in relatively more isotope being retained in a medium molecular mass protein considered to be albumin, and relatively less in another fraction considered to be selenoprotein P. The lack of many observed changes in retention of stable Se, and the shift in retention among the plasma proteins, suggests that supplemental Se was not being used to replete critical pools of Se, probably because of adaptation to low Se intake.

A comparison of methods of assessment of dietary selenium intakes in Otago, New Zealand.

The aims of the present study were (1) to compare three methods of assessment of dietary Se intake, i.e. chemical analysis of duplicate diets, diet records and a food-frequency questionnaire (FFQ) designed specifically for Se, and (2) to determine dietary Se intakes of residents of Otago, New Zealand. The FFQ was completed by 110 free-living adults. Diet records (3 d) and duplicate diet collections were carried out by forty-three of these subjects chosen on the basis of low blood Se concentration, and during a period when consumption of the high-Se foods fish, kidney, liver and Brazil nuts was discouraged. Mean Se intakes were similar for duplicate diet analysis (29 (SD 13) micrograms/d) and diet record assessments (28 (SD 15) micrograms/d). Estimates of intakes from the FFQ for the subgroup of forty-three subjects were higher (51 (SD 26) micrograms/d) than those from duplicate diets and diet records. Values from duplicate diet analysis and diet record assessments were strongly correlated (r 0.7, P = 0.0001), but difference plots indicated a lack of agreement between the two methods. Thus, diet record assessment was not adequate for predicting dietary Se intakes of individuals. Significant correlations were found for relationships between Se intake from duplicate diets (microgram/kg body weight per d) and plasma Se, Se intake from diet records (microgram/d and microgram/kg body weight per d) and plasma Se; and Se intake from the FFQ and whole-blood Se. Se intakes from duplicate diets and diet records were similar to those reported previously for New Zealanders, but lower than the recommended intakes in the USA (National Research Council, 1989), Australia (Truswell et al. 1990) and the UK (Department of Health, 1991) and the World Health Organization/Food and Agriculture Organization/International Atomic Energy Agency (1996) normative requirement.

Selenium speciation in human body fluids.

Selenium consumed by humans in foods and in supplements exists in a number of different organic and inorganic forms including selenomethionine, selenocysteine, selenate and selenite. Animal and human studies have established that the bioavailability of the selenium depends upon the chemical form, which also influences the distribution of selenium in the body. These studies have included urinary excretion of selenium following ingestion of different forms of selenium and the response of tissue selenium concentrations and activities of functional selenoproteins to these selenium compounds. Selenomethionine is retained in tissue proteins to a greater extent than selenocysteine and the inorganic forms, but the selenium is not necessarily immediately available for functional selenoproteins. A number of other factors besides chemical form may also influence the bioavailability and distribution of selenium, including other dietary components, selenium status, physiological status and species. Knowledge of these factors and of speciation of selenium in foods, tissues and functional selenoproteins is important for the accurate assessment of selenium status. Speciation of selenium also has implications with respect to the determination of selenium requirements and to the investigation of relationships between selenium status and health and disease.

Long-term supplementation with selenate and selenomethionine: urinary excretion by New Zealand women.

Thirty-six New Zealand women aged between 18 and 23 years received daily for 32 weeks, 200 micrograms Se as Se-enriched yeast (selenomethionine, SeMet), or brewer's yeast mixed with selenate, or no added Se (placebo) in a double-blind trial. Mean daily Se excretion increased with both supplements; the selenate group excreted more than the SeMet group, 123 v. 66 micrograms/d respectively at week 2, equivalent to 57 v. 27% of the dose. Thereafter Se output increased for the SeMet group reaching a plateau at about 100 micrograms/d at week 16, when plasma Se had also plateaued at 190 ng/ml. The selenate group had reached an earlier plateau of 110 ng Se/ml at week 7. There was a close relationship between 24 h urine and plasma Se for the SeMet group but not for the selenate group. Renal plasma clearances showed two distinctly different responses; the clearance of 0.4 ml/min reached by the SeMet group at week 2 plateaued as plasma Se increased almost 2-fold; whereas for the selenate group the clearance varied between 0.8 and 1.1 ml/min whilst plasma Se remained almost constant at 110 ng/ml. Previous studies, also of 200 micrograms Se/d as Se-rich bread, in New Zealand (NZ) and elsewhere showed similar responses to Se-yeast; the selenite response was intermediate between selenate and Se-yeast (SeMet). The full significance of these studies awaits identification of Se components in plasma, glomerular filtrate and urine; meanwhile renal clearances serve as a pointer to changes in the distribution of Se-containing fractions in the plasma. Trimethylselenonium was detected in basal urines, and was a minor component in urines of supplemented NZ subjects at about 1% of the total Se.

An evaluation of urinary measures of iodine and selenium status.

The aim of this study was to establish methodology for a survey of the iodine and selenium status of New Zealand residents, more specifically to investigate the correlation between fasting or random casual urine samples and 24 hour urines for iodine and selenium excretion. Sixty-two (31 M, 31 F) adults collected casual, fasting and 24 hour urine samples for analysis of iodide, selenium and creatinine. Plasma and serum samples were collected for analysis of selenium and glutathione peroxidase activity. Results indicated that fasting urine samples, but not casual urines, may give a reasonable estimate of urinary output of iodine and selenium on a population basis, but that 24 hour urines are necessary for diagnosis of iodine deficiency in an individual and for research purposes. The results for iodine also give no support for expressing iodine as the iodide-creatinine ratio, although there was some indication that the selenium-creatinine ratio might be useful. Significant correlations between total daily excretion of selenium and iodine and also for urinary concentrations of the two trace elements in fasting and in 24 hour urine specimens may reflect a relationship of selenium and iodine to body size which may have implications for dietary requirements of these trace elements. Alternatively the correlations may reflect a relationship between dietary intake of the two trace elements in a country in which food concentrations are low, and this needs further investigation.

The changing selenium status of New Zealand residents.

OBJECTIVE: The aim of this paper was to compile all the studies of selenium status carried out in Otago and in other areas of New Zealand in order to follow the history of selenium status in New Zealand residents over the last 20 years. DESIGN: Since 1970 baseline blood samples have been collected from several groups of healthy adult subjects, either for the assessment of Se status or to determine baseline Se levels as part of a number of other studies. A comparison has been made of selenium concentrations recorded in recent published and unpublished studies with earlier studies by the Otago research group, and also those by other groups in New Zealand. SETTING: Otago and other New Zealand centres. RESULTS: Blood selenium concentrations of Otago residents were consistently low from 1972 until 1988 at around 0.77 mumol/l, apart from a temporary increase in 1985, and then rose to reach 1.03 mumol/l in 1991 and 1.19 mumol/l in 1992-3. Blood selenium status reflected changes in the importation of Australian wheat. Correlations between selenium and glutathione peroxidase in whole blood and plasma were consistently high prior to 1989, but were no longer significant from 1990. CONCLUSIONS: The lack of a correlation between selenium and glutathione peroxidase in bloods collected after 1990 indicates that at least for glutathione peroxidase, the selenium intake of New Zealanders is now close to that required for saturation. Whether this is sufficient to meet the requirements for other functional selenoproteins or for a possible cancer prevention effect remains to be determined.

Sequence and biochemical similarities between the luciferases of the glow-worm Lampyris noctiluca and the firefly Photinus pyralis.

A full-length clone encoding Lampyris noctiluca (British glow-worm) luciferase was isolated from a complementary DNA (cDNA) expression library constructed with MRNA extracted from light organs. The luciferase was a 547-residue protein, as deduced from the nucleotide sequence. The protein was closely related to those of other lampyrid beetles, the similarity to Photinus pyralis luciferase being 84% and to Luciola 67%. In contrast, Lampyris luciferase had less sequence similarity to the luciferases of the click beetle Pyrophorus, at 48%. Engineering Lampyris luciferase in vitro showed that the C-terminal peptide containing 12 amino acids in Photinus and 9 amino acids in Lampyris was essential for bioluminescence. The pH optimum and the Km values for ATP and luciferin were similar for both Photinus and Lampyris luciferases, although the light emitted by the latter shifted towards the blue and was less stable at 37 degrees C. It was concluded that the molecular and biochemical properties were not sufficient to explain the glowing or flashing of the two beetles Lampyris and Photinus.