Influence of prepartum dietary cation-anion difference and the magnitude of calcium decline at the onset of lactation on mineral metabolism and physiological responses.

The onset of lactation is characterized by substantially altered calcium (Ca) metabolism; recently, emphasis has been placed on understanding the dynamics of blood Ca in the peripartal cow in response to this change. Thus, the aim of our study was to delineate how prepartum dietary cation-anion difference (DCAD) diets and the magnitude of Ca decline at the onset of lactation altered blood Ca dynamics in the periparturient cow. Thirty-two multiparous Holstein cows were blocked by parity, previous 305-d milk yield and expected parturition date, and randomly allocated to either a positive (+120 mEq/kg) or negative (-120 mEq/kg) DCAD diet from 251 d of gestation until parturition (n = 16/diet). Immediately after parturition cows were continuously infused for 24 h with (1) an intravenous solution of 10% dextrose or (2) Ca gluconate (CaGlc) to maintain blood ionized (iCa) concentrations at ∼1.2 mM (normocalcemia) to form 4 treatment groups (n = 8/treatment). Blood was sampled every 6 h from 102 h before parturition until 96 h after parturition and every 30 min during 24 h continuous infusion. Cows fed a negative DCAD diet prepartum exhibited a less pronounced decline in blood iCa approaching parturition with lesser magnitude of decline relative to positive DCAD-fed cows. Cows fed a negative DCAD diet prepartum required lower rates of CaGlc infusion to maintain normocalcemia in the 24 h postpartum relative to positive DCAD-fed cows. Infusion of CaGlc disrupted blood Ca and P dynamics in the immediate 24 h after parturition and in the days following infusion. Collectively, these data demonstrate that prepartum negative DCAD diets facilitate a more transient hypocalcemia and improve blood Ca profiles at the onset of lactation whereas CaGlc infusion disrupts mineral metabolism.

Biological responses to extreme weather events are detectable but difficult to formally attribute to anthropogenic climate change.

As the frequency and intensity of extreme events such as droughts, heatwaves and floods have increased over recent decades, more extreme biological responses are being reported, and there is widespread interest in attributing such responses to anthropogenic climate change. However, the formal detection and attribution of biological responses to climate change is associated with many challenges. We illustrate these challenges with data from the Elbe River floodplain, Germany. Using community turnover and stability indices, we show that responses in plant, carabid and mollusc communities are detectable following extreme events. Community composition and species dominance changed following the extreme flood and summer heatwave of 2002/2003 (all taxa); the 2006 flood and heatwave (molluscs); and after the recurring floods and heatwave of 2010 and the 2013 flood (plants). Nevertheless, our ability to attribute these responses to anthropogenic climate change is limited by high natural variability in climate and biological data; lack of long-term data and replication, and the effects of multiple events. Without better understanding of the mechanisms behind change and the interactions, feedbacks and potentially lagged responses, multiple-driver attribution is unlikely. We discuss whether formal detection and/or attribution is necessary and suggest ways in which understanding of biological responses to extreme events could progress.

Plastic contamination of the food chain: A threat to human health?

Macro-plastic pollution is found in terrestrial and marine environments and is degraded to micro-particles (MP) and nano-particles (NP) of plastic. These can enter the human food chain either by inhalation or by ingestion, particularly of shellfish and crustaceans. Absorption across the gastrointestinal tract is relatively low, especially for MPs, which appear to have little toxicity. However, NPs are more readily absorbed and may accumulate in the brain, liver and other tissues in aquatic species and other animals. Studies using nanoparticles of other materials suggest that toxicity could potentially affect the central nervous system and the reproductive system, although this would be unlikely unless exposure levels were very high and absorption was increased by physiological factors.

Drug metabolism in the elderly: A multifactorial problem?

Whether or not an individual's drug metabolising capacity declines with advancing age is a vexing question. There is no clear evidence that drug metabolism itself ('the biologically-assisted chemical alteration of the administered parent molecule') is less efficient in healthy old age than at younger ages, whereas a decreased capacity may be associated with ill-health and frailty. However, elderly individuals do show a reduced enzyme induction capability and are less able to tolerate overdoses. It appears that the majority of deleterious clinical outcomes related to drug therapy in an elderly (usually ill or frail) population may be ascribed to various anatomical and physiological age-related changes. These may affect both pharmacodynamics and pharmacokinetics, but not necessarily drug metabolism. Information gleaned from animal studies undertaken mainly in rodents does not seem to be of relevance to humans and studies in healthy aged human populations may not highlight possible problems. However, certain circumstances may influence metabolic competence, and phenotyping rather than genotyping is of more value in identifying those susceptible to adverse drug reactions. This short review discusses the potential contributions of four factors (inflammation, circadian rhythm, gut microbes, epigenetic aspects) which may lead to alterations in drug metabolism with increasing age.

In utero exposure to carcinogens: Epigenetics, developmental disruption and consequences in later life.

The uterine environment is often viewed as a relatively safe haven, being guarded by the placenta which acts as a filter, permitting required materials to enter and unwanted products to be removed. However, this defensive barrier is sometimes breached by potential chemical hazards to which the mother may be subjected. Many of these toxins have immediate and recognisable deleterious effects on the embryo, foetus or neonate, but a few are insidious and leave a legacy of health issues that may emerge in later life. Several substances, falling into the categories of metals and metalloids, endocrine disruptors, solvents and other industrial chemicals, have been implicated in the development of long-term health problems in the offspring following maternal and subsequent in utero exposure. The mechanisms involved are complex but often involve epigenetic changes which disrupt normal cell processes leading to the development of cancers and also dysregulation of biochemical pathways.

Private land manager capacity to conserve threatened communities under climate change.

Major global changes in vegetation community distributions and ecosystem processes are expected as a result of climate change. In agricultural regions with a predominance of private land, biodiversity outcomes will depend on the adaptive capacity of individual land managers, as well as their willingness to engage with conservation programs and actions. Understanding adaptive capacity of landholders is critical for assessing future prospects for biodiversity conservation in privately owned agricultural landscapes globally, given projected climate change. This paper is the first to develop and apply a set of statistical methods (correlation and bionomial regression analyses) for combining social data on land manager adaptive capacity and factors associated with conservation program participation with biophysical data describing the current and projected-future distribution of climate suitable for vegetation communities. We apply these methods to the Tasmanian Midlands region of Tasmania, Australia and discuss the implications of the modelled results on conservation program strategy design in other contexts. We find that the integrated results can be used by environmental management organisations to design community engagement programs, and to tailor their messages to land managers with different capacity types and information behaviours. We encourage environmental agencies to target high capacity land managers by diffusing climate change and grassland management information through well respected conservation NGOs and farm system groups, and engage low capacity land managers via formalized mentoring programs.

Xenobiotic sulphation and its variability during inflammation: a factor in adverse drug reactions?

The interactions between disease processes and the metabolism of therapeutic drugs have not been systematically investigated. Inflammation, with the presence of pro-inflammatory cytokines, affects Phase 1 metabolism, particularly the activity of the CYP isoforms. Inflammatory factors also alter the activity of some Phase 2 enzymes, particularly the sulphotransferases (SULT isoforms) responsible for drug sulphonation and the enzyme pathway involved in the supply of sulphate for this reaction. Being ill may, therefore, in itself make drug metabolism unpredictable.

Diethylstilboestrol--a long-term legacy.

Diethylstilboestrol (DES) is an endocrine disrupter which causes cancer in rodents. It was prescribed in large amounts to treat women with gynaecological problems; some of the daughters of these women subsequently developed a rare cancer (vaginal clear cell adenocarcinoma) while genital abnormalities were found in some of the sons. It was used for decades in livestock feed and this may have contaminated the food chain leading to the exposure of the more general population. DES appears to cause epigenetic effects in animals and there is some evidence that this also occurs in man. The mechanisms of carcinogenesis are complex and the effects are difficult to prove due to the background of dietary and environmental phyto- and xenooestrogens. It has been suggested that, like other endocrine disrupters, DES may have acted as an obesogen in the human population.

Biomarkers of endocrine disruption: cluster analysis of effects of plasticisers on Phase 1 and Phase 2 metabolism of steroids.

Although some endocrine disruptors (EDs) act at steroid receptors, it is now apparent that compounds may have ED potential if they alter steroid synthesis or metabolism, particularly if they affect Phase 1 or Phase 2 pathways. In the ENDOMET project (EU-funded 5th Framework programme), 23 different assays were used on a wide range of EDs. Cluster analysis of the matrix results enabled identification of four integrated test systems that can be used to pinpoint compounds that are able to alter steroid metabolism or function. Critical pathways were shown to include oestrogen synthesis and sulphonation, synthesis of sulphate/PAPS and thyroid hormone regulation so that the activity profiles of some Phase 1 and Phase 2 reactions can be used as biomarkers for detection of compounds with ED potential.

Endocrine disrupters--a threat to women's health?

Endocrine disruption has been a topic of public concern for many years and its study remains high on the scientific agenda. Endocrine disrupters (EDs) are compounds which may be of industrial or natural origin and which act to dysregulate steroid function and metabolism. As well as their actions on nuclear steroid receptors, EDs can inhibit the pathways of steroid synthesis and degradation. They not only affect reproductive function but also affect a range of tissues which are steroid sensitive such as the central nervous system and thyroid. Results from the latest studies suggest that EDs may also affect the immune system, glucose homeostasis and can act as epigenetic modulators resulting in transgenerational effects. Research in this area has led to the development of drugs used in the treatment of several types of hormone-sensitive cancer. However, despite many years of effort, the effects on human health of long-term environmental exposure to EDs, whether singly or as mixtures, remain unknown.

Reactive oxygen species and oxidative DNA damage mediate the cytotoxicity of tungsten-nickel-cobalt alloys in vitro.

Tungsten alloys (WA) have been introduced in an attempt to find safer alternatives to depleted uranium and lead munitions. However, it is known that at least one alloy, 91% tungsten-6% nickel-3% cobalt (WNC-91-6-3), causes rhabdomyosarcomas when fragments are implanted in rat muscle. This raises concerns that shrapnel, if not surgically removable, may result in similar tumours in humans. There is therefore a clear need to develop rapid and robust in vitro methods to characterise the toxicity of different WAs in order to identify those that are most likely to be harmful to human health and to guide development of new materials in the future. In the current study we have developed a rapid visual in vitro assay to detect toxicity mediated by individual WA particles in cultured L6-C11 rat muscle cells. Using a variety of techniques (histology, comet assay, caspase-3 activity, oxidation of 2'7'-dichlorofluorescin to measure the production of reactive oxygen species and whole-genome microarrays) we show that, in agreement with the in vivo rat carcinogenicity studies, WNC-91-6-3 was the most toxic of the alloys tested. On dissolution, it produces large amounts of reactive oxygen species, causes significant amounts of DNA damage, inhibits caspase-3, triggers a severe hypoxic response and kills the cells in the immediate vicinity of the alloy particles within 24h. By combining these in vitro data we offer a mechanistic explanation of the effect of this alloy in vivo and show that in vitro tests are a viable alternative for assessing new alloys in the future.

Brain organization mirrors caste differences, colony founding and nest architecture in paper wasps (Hymenoptera: Vespidae).

The cognitive challenges that social animals face depend on species differences in social organization and may affect mosaic brain evolution. We asked whether the relative size of functionally distinct brain regions corresponds to species differences in social behaviour among paper wasps (Hymenoptera: Vespidae). We measured the volumes of targeted brain regions in eight species of paper wasps. We found species variation in functionally distinct brain regions, which was especially strong in queens. Queens from species with open-comb nests had larger central processing regions dedicated to vision (mushroom body (MB) calyx collars) than those with enclosed nests. Queens from advanced eusocial species (swarm founders), who rely on pheromones in several contexts, had larger antennal lobes than primitively eusocial independent founders. Queens from species with morphologically distinct castes had augmented central processing regions dedicated to antennal input (MB lips) relative to caste monomorphic species. Intraspecific caste differences also varied with mode of colony founding. Independent-founding queens had larger MB collars than their workers. Conversely, workers in swarm-founding species with decentralized colony regulation had larger MB calyx collars and optic lobes than their queens. Our results suggest that brain organization is affected by evolutionary transitions in social interactions and is related to the environmental stimuli group members face.

Sulfotransferase inhibition: potential impact of diet and environmental chemicals on steroid metabolism and drug detoxification.

The cytosolic sulfotransferase enzymes (SULT isoforms) utilise PAPS (3'-phosphoadenosine-5'-phosphosulfate) as co-factor to transfer sulfonate groups onto a wide range of substrates. SULT1A3 has catecholamines such as dopamine as substrates while SULT 1E1 sulfonates oestrogens. SULT 1A1 sulfonates phenols and also oestrogens at a higher K(m) than SULT 1E1. SULT 2A1 mainly sulfonates DHEA and some steroids, with hydroxy derivatives of polycyclic aromatic hydrocarbons. Studies on these isoforms with a range of environmental chemicals and dietary components have shown that SULT 1A1 is significantly inhibited by flavonoids; all flavones and flavonols with a 3',4'-dihydroxy motif had an IC(50) of < 100 nm against 3 microM 4-nitrophenol as the standard substrate. SULTs 1A3 and 2A1 were less strongly inhibited by flavonoids or isoflavonoids although tricin (3',5'-dimethoxy-4',5,7-trihydroxyflavone is a competitive inhibitor of SULT 1E1 with an inhibition constant of approximately 1 nM. Fruit and vegetable cytosols also inhibit SULT isoforms, as do long-chain alkylphenols and chlorinated phenols. Phthalates (used as plasticisers) inhibited SULTs 1E1 and 2A1. As these environmental contaminants and dietary components all act at the same site, their effects would be expected to be additive and could potentially therefore reduce sulfonation of drugs and lead to altered pharmacological responses.

Phytoestrogens and xenoestrogens: the contribution of diet and environment to endocrine disruption.

Some endocrine disrupting compounds such as phthalates and phenols act non-genomically by inhibiting the sulfotransferase (SULT 1E1 and SULT 1A1) isoforms which inactivate estrogens by sulfonation. A range of environmental phenolic contaminants and dietary flavonoids was tested for inhibition of the human SULT 1A1, 1E1 and 2A1 isoforms. In particular, the plasticisers 4-n-octyl- and 4-n-nonyl-phenol inhibit SULT 1E1 with IC(50) values of 0.16 microM vs. 10nM estradiol while the 2-substituted chlorophenols show similar values. Flavonoids are also SULT inhibitors; tricin is a competitive inhibitor of SULT 1E1 with a K(i) of 1.5+/-0.8 nM. In a small pilot study to determine whether ingestion of soy flavonoids would affect SULT1A1 activity in vivo as well as in vitro, sulfonation of daidzein was reduced in a group of women 'at risk' of breast cancer, as compared with controls, although the SULT 1A1*1/SULT 1A1*2 allele ratio was not different. Endocrine disrupting effects in man may be multifactorial when components from both the diet and the environment act at the same point in steroid metabolism.

An amino-terminal DAX1 (NROB1) missense mutation associated with isolated mineralocorticoid deficiency.

CONTEXT: Mutations in DAX1 (dosage-sensitive sex reversal-adrenal hypoplasia congenita critical region on the X chromosome gene 1; NR0B1) cause X-linked adrenal hypoplasia congenita, a disease characterized by primary adrenal failure, testicular dysgenesis, and gonadotropin deficiency. Most DAX1 mutations are deletions, nonsense, or frameshift mutations that markedly impair its transcriptional activity. Missense mutations have been restricted to the carboxy-terminal domain and are associated with more variable clinical phenotypes. OBJECTIVE: The objective was to identify novel clinical phenotypes associated with DAX1 missense mutations. PATIENTS AND DESIGN: We investigated the genetic basis of isolated mineralocorticoid deficiency in a patient who carries a unique missense mutation (W105C) in the amino-terminal region of DAX1. RESULTS: The W105C DAX1 mutation in the proband was present in three asymptomatic hemizygous males, but it was not detected in the general population. Using in vitro studies of DAX1 expression and function in transfected cells, we demonstrate that the mutant DAX1 protein exhibits mild loss of function, whether studied for genes it represses or for genes it activates. Structure-function studies suggest that the W105C and other mutations in the aminoterminus are compensated by the presence of repeated LXXLL motifs that mediate DAX1 interactions with other proteins. CONCLUSIONS: We describe the first missense mutation in the aminoterminus of DAX1 and conclude that mutations in this region may be partially compensated by redundant functional domains. Mild DAX1 mutations may be a cause of isolated mineralocorticoid deficiency.

Induction of cysteine dioxygenase activity by oral administration of cysteine analogues to the rat: implications for drug efficacy and safety.

One of the major steps in the oxidation of the sulphur-containing amino acid, L-cysteine, is the production of cysteine sulphinic acid, catalysed by the enzyme cysteine dioxygenase. This enzyme plays a key role in the intermediary metabolism of sulphur-containing compounds. The activity of this crucial enzyme is known to be influenced by sulphur-compound intake, being increased in animals fed an excess of L-cysteine or methionine. However, the affects on this enzyme of the chronic administration of drugs similar in structure to cysteine are unknown. This has now been investigated using the anti-rheumatic agent, D-penicillamine, and the mucoactive compound, S-carboxymethyl-L-cysteine. Repeated oral administration of these sulphur-containing drugs to male Wistar rats for five consecutive days led to a significant increase in hepatic cysteine dioxygenase activity. This increase in the production rate of cysteine sulphinic acid remained evident until returning to control levels four days after cessation of drug administration. These observations provide evidence that these two drugs interact with the intermediary biochemistry of sulphur compounds and may provide hitherto unappreciated insights into mechanisms by which therapeutic effects and adverse reactions may occur.

Endocrine disrupters: a human risk?

Endocrine disrupters (EDs) alter normal hormonal regulation and may be naturally occurring or environmental contaminants. Classically, EDs act genomically, with agonistic or antagonistic effects on steroid receptors and may alter reproductive function and/or cause feminisation by binding to oestrogen or androgen receptors; their binding to the thyroid receptor may dysregulate the neuroendocrine system. Recently, it has been shown that EDs can also act by non-genomic mechanisms, altering steroid synthesis (inhibition of cytochrome P450 isoforms) or steroid metabolism. The alkylphenol and phthalate plasticisers inhibit the inactivation of oestrogens by sulphation (via SULT 1A1 and 1E1 isoforms) and so cause a rise in levels of the free active endogenous oestrogens. A range of ED effects have been shown in mammals, fish, birds, reptiles, amphibia and aquatic invertebrates but it is not yet clear whether these processes also occur in human beings. It is evident that EDs, as well as altering reproduction, can cause changes in neurosteroid levels and so have the potential to affect immune function, behaviour and memory. This may be of long-term concern since traces of EDs such as plasticisers, brominated fire retardants, sunscreen agents and cosmetic ingredients are widely distributed in the environment and in human biofluids.

Non-genomic effects of endocrine disrupters: inhibition of estrogen sulfotransferase by phenols and chlorinated phenols.

Phenols are used world-wide and their presence in the environment is a cause of increasing concern. Despite evidence to suggest that, in general, they bind poorly to estrogen receptors, they are suspected of being endocrine disrupters. Here, we show that 2, x-substituted phenols are potent inhibitors of estrogen sulfotransferase with IC(50) values at low- or sub-micromolar levels. Our results demonstrate a potential non-genomic mechanism of action for these compounds and suggest that, where viable alternatives exist, both phenols substituted in the 2-position and their metabolic precursors should be avoided.

Measurement of exogenous carbohydrate oxidation: a comparison of [U-14C]glucose and [U-13C]glucose tracers.

The purpose of this study was to assess the level of agreement between two techniques commonly used to measure exogenous carbohydrate oxidation (CHO(EXO)). To accomplish this, seven healthy male subjects (24 +/- 3 yr, 74.8 +/- 2.1 kg, V(O2(max)) 62 +/- 4 ml x kg(-1) x min(-1)) exercised at 50% of their peak power for 120 min on two occasions. During these exercise bouts, subjects ingested a solution containing either 144 g glucose (8.7% wt/vol glucose) or water. The glucose solution contained trace amounts of both [U-13C]glucose and [U-14C]glucose to allow CHO(EXO) to be quantified simultaneously. The water trial was used to correct for background 13C enrichment. 13C appearance in the expired air was measured using isotope ratio mass spectrometry, whereas 14C appearance was quantified by trapping expired CO(2) in solution (using hyamine hydroxide) and adding a scintillator before counting radioactivity. CHO(EXO) measured with [13C]glucose ([13C]CHO(EXO)) was significantly greater than CHO(EXO) measured with [14C]glucose ([14C]CHO(EXO)) from 30 to 120 min. There was a 15 +/- 4% difference between [13C]CHO(EXO) and [14C]CHO(EXO) such that the absolute difference increased with the magnitude of CHO(EXO). Further investigations suggest that the difference is not because of losses of CO2 from the trapping solution before counting or an underestimation of the "strength" of the trapping solution. Previous research suggests that the degree of isotopic fractionation is small (S. C. Kalhan, S. M. Savin, and P. A. Adam. J Lab Clin Med89: 285-294, 1977). Therefore, the explanation for the discrepancy in calculated CHO(EXO) remains to be fully understood.

Effects of culture with TNF-alpha, TGF-beta and insulin on sulphotransferase (SULT 1A1 and 1A3) activity in human colon and neuronal cell lines.

The aim of the study was to determine whether the expression of sulphotransferase enzymes could be affected by the presence of cytokines or peptide hormones. The effects of cytokines (TNF-alpha and TGF-beta) and insulin on sulphotransferase (SULT 1A1 and 1A3) activity were studied in a human neuronal cell line (SK-N-SH) and a human gastrointestinal tract cell line (HT-29). Cells were cultured with varying concentrations of TNF-alpha, TGF-beta or insulin for 24 h; the SULT 1A1 isoform in the 2 cell lines showed different optimal substrate concentrations. There were no direct effects of cytokines on enzyme activity. Culture with TNF-alpha increased activity of both SULT 1A1 and 1A3 in the HT-29 cells; TGF-beta also increased activities of both isoforms but to a lesser extent; insulin increased activity of SULT 1A1 only. The cytokines and insulin had relatively little effect on sulphotransferase activity in the neuronal cell line. These results suggest that, unlike neuronal cells, gastrointestinal cells may respond to physiological states by altering sulphotransferase activity. As certain substrates such as diet-derived heterocyclic amines are bioactivated by sulphation to produce carcinogenic metabolites this may be a factor in the increased incidence of colorectal cancer in patients with inflammatory bowel disease or diabetes.