Extinction risk predictions for the world's flowering plants to support their conservation

More than 70% of all vascular plants lack conservation status assessments. We aimed to address this shortfall in knowledge of species extinction risk by using the World Checklist of Vascular Plants to generate the first comprehensive set of predictions for a large clade: angiosperms (flowering plants, c. 330 000 species). We used Bayesian Additive Regression Trees (BART) to predict the extinction risk of all angiosperms using predictors relating to range size, human footprint, climate, and evolutionary history and applied a novel approach to estimate uncertainty of individual species-level predictions. From our model predictions, we estimate 45.1% of angiosperm species are potentially threatened with a lower bound of 44.5% and upper bound of 45.7%. Our species-level predictions, with associated uncertainty estimates, do not replace full global, or regional Red List assessments, but can be used to prioritise predicted threatened species for full Red List assessment and fast-track predicted non-threatened species for Least Concern assessments. Our predictions and uncertainty estimates can also guide fieldwork, inform systematic conservation planning and support global plant conservation efforts and targets.

Re-evaluating the importance of threatened species in maintaining global phytoregions

Anthropogenic introductions are known to be changing the structure of global phytogeographical regions (phytoregions), but previous studies have been limited by incomplete or biased data sets that are likely to underestimate the importance of threatened species. In this work, we analyse a comprehensive data set of all known species and their occurrences (at botanical country resolution) to quantify the impact of potential future extinction scenarios. We used Infomap, a network-based community detection algorithm, to generate phytoregional delineations for six species-distribution scenarios (native, introduced and extinctions of species that are either documented as threatened or likely to be threatened, as well as combinations thereof). We compared the numbers and sizes of phytoregions to characterise the amount and spatial distribution of changes in global phytoregions under each scenario. Extinctions of species that are predicted to be threatened had a greater homogenising effect on phytoregions than introductions, and there was some evidence that introductions may even mitigate the homogenisation caused by extinctions, though this interaction is complex. This research provides the first evidence that the loss of threatened species would have significant ramifications for global phytoregions and demonstrates the need to consider extinction processes in studies of anthropogenic effects on biodiversity patterns.

rWCVP: a companion R package for the World Checklist of Vascular Plants

The World Checklist of Vascular Plants (WCVP) is an extremely valuable resource that is being used to address many fundamental and applied questions in plant science, conservation, ecology and evolution. However, databases of this size require data manipulation skills that pose a barrier to many potential users. Here, we present rWCVP, an open-source R package that aims to facilitate the use of the WCVP by providing clear, intuitive functions to execute many common tasks. These functions include taxonomic name reconciliation, geospatial integration, mapping and generation of multiple different summaries of the WCVP in both data and report format. We have included extensive documentation and tutorials, providing step-by-step guides that are accessible even to users with minimal programming experience. rWCVP is available on cran and GitHub.

Evidence-based guidelines for automated conservation assessments of plant species

Assessing species' extinction risk is vital to setting conservation priorities. However, assessment endeavors, such as those used to produce the IUCN Red List of Threatened Species, have significant gaps in taxonomic coverage. Automated assessment (AA) methods are gaining popularity to fill these gaps. Choices made in developing, using, and reporting results of AA methods could hinder their successful adoption or lead to poor allocation of conservation resources. We explored how choice of data cleaning type and level, taxonomic group, training sample, and automation method affect performance of threat status predictions for plant species. We used occurrences from the Global Biodiversity Information Facility (GBIF) to generate assessments for species in 3 taxonomic groups based on 6 different occurrence-based AA methods. We measured each method's performance and coverage following increasingly stringent occurrence cleaning. Automatically cleaned data from GBIF performed comparably to occurrence records cleaned manually by experts. However, all types of data cleaning limited the coverage of AAs. Overall, machine-learning-based methods performed well across taxa, even with minimal data cleaning. Results suggest a machine-learning-based method applied to minimally cleaned data offers the best compromise between performance and species coverage. However, optimal data cleaning, training sample, and automation methods depend on the study group, intended applications, and expertise.

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

Madagascar’s biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar’s past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique “living laboratory” for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth’s biodiversity.

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar’s unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar’s terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as the most prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar.

Harnessing Large-Scale Herbarium Image Datasets Through Representation Learning

The mobilization of large-scale datasets of specimen images and metadata through herbarium digitization provide a rich environment for the application and development of machine learning techniques. However, limited access to computational resources and uneven progress in digitization, especially for small herbaria, still present barriers to the wide adoption of these new technologies. Using deep learning to extract representations of herbarium specimens useful for a wide variety of applications, so-called "representation learning," could help remove these barriers. Despite its recent popularity for camera trap and natural world images, representation learning is not yet as popular for herbarium specimen images. We investigated the potential of representation learning with specimen images by building three neural networks using a publicly available dataset of over 2 million specimen images spanning multiple continents and institutions. We compared the extracted representations and tested their performance in application tasks relevant to research carried out with herbarium specimens. We found a triplet network, a type of neural network that learns distances between images, produced representations that transferred the best across all applications investigated. Our results demonstrate that it is possible to learn representations of specimen images useful in different applications, and we identify some further steps that we believe are necessary for representation learning to harness the rich information held in the worlds' herbaria.

Plants used traditionally as antimalarials in Latin America: Mining the tree of life for potential new medicines

ETHNOPHARMACOLOGICAL RELEVANCE

Malaria remains a serious and challenging disease. Traditional antimalarial medicines are largely based on plants, and ethnopharmacological research has inspired the development of antimalarial pharmaceuticals such as artemisinin. Antimalarial drug resistance is an increasing problem in Plasmodium species, and new therapeutic strategies to combat malaria are needed. Although the number of malaria cases has been decreasing in Latin America, malaria remains a significant threat in many regions. Local people in Latin America have been using numerous plant species to treat malaria, some of which have been scientifically studied, but many others have not.

AIM OF THE STUDY

Our principal objective is to harness ethnobotanical data on species used traditionally to treat malaria, combined with phylogenetic approaches, to understand how ethnobotany could help identify plant genera as potential sources of new medicines.

MATERIALS AND METHODS

Plants used to treat malaria in Latin America were compiled from published and grey literature, unpublished data, and herbarium specimens. Initial assessment of potentially important species/genera/families included compiling the number of species used within the genus, the number of use reports per genus and species, and the geographic distribution of their use. The analysis of taxonomic distribution of species reported as antimalarial in Latin America (excluding the Southern Cone) was conducted, to determine which genera and families with reputed antimalarial properties are over-represented, and phylogenetic analyses were performed to identify if there was evidence for antimalarial species being dispersed/clustered throughout the tree or at its tips. This approach enabled 'hot-nodes' in certain families to be identified, to predict new genera with potential antimalarial properties.

RESULTS

Over 1000 plant species have been used to treat malaria in Latin America, of which over 600 species were cited only once. The genera with the highest number of antimalarial species were Aspidosperma, Solanum, Piper, Croton and Aristolochia. In terms of geographic distribution, the most widely used genera were Aspidosperma, Momordica, Cinchona, Senna and Stachytarpheta. Significant phylogenetic signal was detected in the distribution of native species used for malaria, analysed in a genus-level phylogenetic framework. The eudicot and magnoliidae lineages were over-represented, while monocots were not.

CONCLUSION

Analysis of ethnobotanical use reports in a phylogenetic framework reveals the existence of hot nodes for malaria across the Latin American flora. We demonstrate how species and genera currently lacking such reports could be pinpointed as of potential interest based on their evolutionary history. Extending this approach to other regions of the world and other diseases could accelerate the discovery of novel medicines and enhance healthcare in areas where new therapeutic strategies are needed.

Botanical Monography in the Anthropocene

Unprecedented changes in the Earth's biota are prompting urgent efforts to describe and conserve plant diversity. For centuries, botanical monographs - comprehensive systematic treatments of a family or genus - have been the gold standard for disseminating scientific information to accelerate research. The lack of a monograph compounds the risk that undiscovered species become extinct before they can be studied and conserved. Progress towards estimating the Tree of Life and digital information resources now bring even the most ambitious monographs within reach. Here, we recommend best practices to complete monographs urgently, especially for tropical plant groups under imminent threat or with expected socioeconomic benefits. We also highlight the renewed relevance and potential impact of monographies for the understanding, sustainable use, and conservation of biodiversity.

Harnessing the potential of integrated systematics for conservation of taxonomically complex, megadiverse plant groups

The value of natural history collections for conservation science research is increasingly recognized, despite their well-documented limitations in terms of taxonomic, geographic, and temporal coverage. Specimen-based analyses are particularly important for tropical plant groups for which field observations are scarce and potentially unreliable due to high levels of diversity-amplifying identification challenges. Specimen databases curated by specialists are rich sources of authoritatively identified, georeferenced occurrence data, and such data are urgently needed for large genera. We compared entries in a monographic database for the large Neotropical genus Myrcia in 2007 and 2017. We classified and quantified differences in specimen records over this decade and determined the potential impact of these changes on conservation assessments. We distinguished misidentifications from changes due to taxonomic remodeling and considered the effects of adding specimens and georeferences. We calculated the potential impact of each change on estimates of extent of occurrence (EOO), the most frequently used metric in extinction-risk assessments of tropical plants. We examined whether particular specimen changes were associated with species for which changes in EOO over the decade were large enough to change their conservation category. Corrections to specimens previously misidentified or lacking georeferences were overrepresented in such species, whereas changes associated with taxonomic remodeling (lumping and splitting) were underrepresented. Among species present in both years, transitions to less threatened status outnumbered those to more threatened (8% vs 3%, respectively). Species previously deemed data deficient transitioned to threatened status more often than to not threatened (10% vs 7%, respectively). Conservation scientists risk reaching unreliable conclusions if they use specimen databases that are not actively curated to reflect changing knowledge.

The use and misuse of herbarium specimens in evaluating plant extinction risks

Herbarium specimens provide verifiable and citable evidence of the occurrence of particular plants at particular points in space and time, and are vital resources for assessing extinction risk in the tropics, where plant diversity and threats to plants are greatest. We reviewed approaches to assessing extinction risk in response to the Convention on Biological Diversity's Global Strategy for Plant Conservation Target 2: an assessment of the conservation status of all known plant species by 2020. We tested five alternative approaches, using herbarium-derived data for trees, shrubs and herbs in five different plant groups from temperate and tropical regions. All species were previously fully assessed for the IUCN Red List. We found significant variation in the accuracy with which different approaches classified species as threatened or not threatened. Accuracy was highest for the machine learning model (90%) but the least data-intensive approach also performed well (82%). Despite concerns about spatial, temporal and taxonomic biases and uncertainties in herbarium data, when specimens represent the best available evidence for particular species, their use as a basis for extinction risk assessment is appropriate, necessary and urgent. Resourcing herbaria to maintain, increase and disseminate their specimen data is essential to guide and focus conservation action.This article is part of the theme issue 'Biological collections for understanding biodiversity in the Anthropocene'.

Tuning reaction products by constrained optimisation

An effective means of defining optimisation criteria for self-optimising criteria is described, applicable to situations where a compromise is sought between several competing objectives.

Volume of the Sexually Dimorphic Nucleus of the Preoptic Area in Rats Exposed to a Maternal High Fat Diet

Mice and rats exposed to a maternal diet high in fat have an increased risk of reproductive system tumors later in life. To test whether a part of the hypothalamus associated with sex differentiation, the sexually dimorphic nucleus of the preoptic area (SDN-POA), might be involved, this nucleus was measured in the offspring of female rats on a high, or low fat diet during pregnancy and nursing. The measurements showed that the SDN-POA was smaller in female offspring exposed to a maternal high fat diet than in female offspring exposed to a maternal low fat diet. This could result in endocrine disturbances and thus provide a possible explanation for the linkage between high fat exposure prenatally and increased female reproductive system cancer.

Multigenerational effects of dietary fat carcinogenesis in mice

The possibility of multigenerational transmission of a carcinogenic effect from exposure to a maternal diet high in fat was tested in mice. Diets with 2.6 or 29% fat (by weight) were fed to strain CD-1 mice during pregnancy. The female offspring were raised on a control diet (10% fat), mated, and continued on the control diet through pregnancy. Their female offspring were raised to terminal illness and autopsied. The total number of reproductive system tumors, pituitary tumors, and metastases was increased in the offspring with ancestral exposure to high dietary fat but to a lesser extent than had been reported previously for direct prenatal exposure to high maternal dietary fat. Because previous work has given evidence against germ cell transmission, a hypothesis based on a maternal effect was offered to explain the multigenerational carcinogenesis. These results have implications for epidemiological studies.

Intensity of multigenerational carcinogenesis from diethylstilbestrol in mice

Mice exposed prenatally to diethylstilbestrol (DES-exposed mice) can transmit a carcinogenic influence to the next generation (DES-lineage mice) when mated to control mice. The persistence of this effect was studied one generation further (DES-lineage-2 mice) by mating DES-lineage female mice to control males. The interaction of maternal dietary fat levels with DES was also tested by feeding high and low levels of dietary fat during the pregnancies that produced the final two generations. DES-lineage-2 mice, exposed to low or high fat maternal diets, had significantly more tumors than control mice with corresponding dietary fat exposure. The frequency of tumors in DES-lineage-2 mice was not significantly lower than in DES-lineage mice from a previous experiment. Thus, the multigenerational effect of DES is relatively intense in mice. If this type of carcinogenesis can occur in the human population, it poses a major threat to future generations.

Combination oral antioxidant supplementation reduces blood pressure

1. Hypertension affects 30% of adults and low intakes of antioxidants have been associated with increased risk of hypertension and cardiovascular disease. To investigate the effect of short-term high-dose antioxidant supplementation on blood pressure in hypertensive and normotensive outpatients, we undertook a randomized, double-blind, crossover design placebo-controlled study. 2. Forty subjects were recruited from medical outpatient clinics, of whom 38 completed the study. Twenty-one were attending for treatment of hypertension and 17 were normotensive, attending for minor gastrointestinal complaints. Subjects were randomly assigned to receive either 8 weeks placebo followed by 2 weeks washout then 8 weeks antioxidants or vice versa. The combination of antioxidants consisted of 200 mg of zinc sulphate, 500 mg of ascorbic acid, 600 mg of alpha-tocopherol (sodium succinate salt) and 30 mg of beta-carotene daily. 3. Systolic blood pressure fell at the end of the antioxidant phase compared with the placebo phase both in subjects receiving anti-hypertensive therapy (P < 0.01) and those who were normotensive (P = 0.067). Circulating levels of beta-carotene and alpha-tocopherol increased in all subjects during supplementation (P < 0.01) and urine nitrite increased in hypertensive patients (P < 0.05). 4. Short-term oral high-dose combination antioxidant therapy reduces blood pressure, possibly via increased availability of nitric oxide. This study may have implications for the innovative use of antioxidants as an adjunct to anti-hypertensive therapy.

Stage of susceptibility to carcinogenicity of prenatal dietary fat exposure tested by blastocyst transfer

A previous experiment with exposure of female mice to a diet high in fat from 4 weeks of age through to the end of pregnancy demonstrated a substantial increase in the frequency of reproductive system tumors in their female offspring. Over this wide period of exposure, one or more specific periods of sensitivity to the carcinogenic effects of dietary fat should exist. To test whether a high fat diet affects maternal germ cells and/or zygote development through to blastocyst formation, two blastocyst transfer experiments were performed. Blastocysts from a dam on high fat were transferred to a pseudopregnant dam on low fat. The reverse type of transfer was performed for contrast. These experiments did not reveal any significant effect of dietary fat on maternal germ cells or zygote development.

The effects of intravenous antioxidants in patients with septic shock

Oxidative stress is implicated in septic shock. We investigated the effect of intravenous antioxidant therapy on antioxidant status, lipid peroxidation, hemodynamics and nitrite in patients with septic shock. Thirty patients randomly received either antioxidants (n-acetylcysteine 150 mg/kg for 30 min then 20 mg/kg/h plus bolus doses of 1 g ascorbic acid and 400 mg alpha-tocopherol) or 5% dextrose. Basal vitamin C was low and redox-reactive iron was elevated in all patients. In the 16 patients receiving antioxidants, vitamin C increased (p = .0002) but total antioxidant capacity was unaffected. Lipid peroxides were elevated in all patients but did not increase further in the patients receiving antioxidants. Plasma total nitrite also increased (p = .007) in the antioxidant group. Heart rate increased in patients receiving antioxidants at 60 min (p = .018) and 120 min (p = .004). Cardiac index also increased at 60 min (p = .007) and 120 min (p = .05). Systemic vascular resistance index decreased at 120 min in the antioxidant treated patients (p = .003). The effect of antioxidants on hemodynamic variables has not previously been reported. Antioxidant administration may be a useful adjunct to conventional approaches in the management of septic shock.

Congestive cardiac failure following laxative withdrawal

We report the case of a 60-year-old woman who presented with weakness and hypokalaemia due to excessive use of laxatives. When the laxatives were withdrawn, she developed severe congestive cardiac failure requiring treatment with a diuretic and angiotensin-converting enzyme inhibitor. There was no underlying cardiac abnormality, and these drugs were eventually stopped with no recurrence of the cardiac failure. The possible mechanisms of heart failure following laxative withdrawal is discussed.

Effects of fostering on the increased tumor incidence produced by a maternal diet high in fat

Previous work has shown that female offspring of mice fed a diet high in fat during pregnancy developed more reproductive system tumors and metastases than offspring of pregnant mice fed a low-fat diet. The purpose of the current experiment was to use fostering to test whether the sensitive period for this cancer effect involved the early postnatal period. Strain CD-1 female mice were placed on a diet of 2.6% fat or 29% fat from corn oil at 4 weeks of age and bred at 6-10 weeks of age. The special diets were discontinued at birth, and litters from dams that had been fed the low-fat diet were fostered to dams previously fed the high-fat diet, and vice versa. The offspring were raised to terminal illness and autopsied. There was no difference in age at terminal illness or in the number of the common nonreproductive system tumors between the two fostered groups. Tumor metastases appeared in both groups. However, the combined frequency of reproductive tract tumors and mammary tumors was significantly higher in mice exposed prenatally to a low-fat diet and fostered to dams that had consumed a high-fat diet during pregnancy than in mice exposed prenatally to a high-fat diet and fostered to a dam fed a low-fat diet. Thus the most sensitive period for a cancer effect from high fat was early postnatal, even though the special diets had been discontinued at birth. This matches the period of greatest sensitivity for sex differentiation of the hypothalamus.

Regulation of nitric oxide synthase activity in cultured human endothelial cells: effect of antioxidants

Nitric oxide release is induced in many cells, including vascular endothelium, as part of the host response to inflammation. Nitric oxide synthase activity is increased in patients with sepsis, associated with increased oxidant demands and decreased antioxidant protection. We used a human vascular endothelial cell line to investigate the influence of antioxidants on nitric oxide synthase activity. Cells were cultured to confluence and incubated with interferon gamma, tumor necrosis factor, and lipopolysaccharide in the combined presence of the antioxidants ascorbic acid, Trolox, catalase, or superoxide dismutase, singly and in combination, for 48 h. Additionally, some cells were incubated with hypoxanthine-xanthine oxidase or a nitric oxide donor. Nitric oxide synthase activity was upregulated by cytokine exposure (p < .0005). Ascorbic acid and superoxide dismutase/ catalase resulted in decreased enzyme activity (p < .05). Superoxide anion release from xanthine oxidase caused increased activity (p < .05) and exogenous nitric oxide tended to suppress synthase activity. We suggest that antioxidants scavenge superoxide anion, enabling feedback inhibition of nitric oxide synthase activity by nitric oxide, and thus reducing enzyme activity. Exogenous nitric oxide also has a similar effect. Superoxide generation suppresses this feedback inhibition. This study has important implications in patients with sepsis in whom nitric oxide synthase inhibitor therapy is currently under investigation.

Increased reproductive tract tumors in the female offspring of mice fed a high fat diet during the fetal stage of pregnancy

In a previous study, female offspring of mice consuming a high fat diet throughout pregnancy developed reproductive system tumors and tumor metastases with a frequency significantly higher than offspring of mice on a low fat diet. To test for the sensitive period more specifically, the feeding of a high fat diet was restricted to the fetal period of pregnancy in the present experiment. The offspring were raised to terminal illness and autopsied. The total number of ovarian, uterine and mammary tumors was 14 among 74 mice exposed prenatally to low fat and 34 among 75 mice exposed prenatally to high fat (P < 0.002). In mice exposed to high fat during the fetal period 13 tumors produced metastases, but no metastases were identified after exposure to low fat (P < 0.001). Thus, a maternal diet high in fat during the fetal period of pregnancy was sufficient to increase reproductive system tumors and metastases in the female offspring.

Total antioxidant capacity and lipid peroxidation during liver transplantation

1. We assessed plasma total antioxidant capacity using enhanced chemiluminescence and plasma lipid peroxides in eight patients undergoing orthotopic liver transplantation and 26 healthy control subjects. 2. The antioxidant capacity of plasma decreased significantly on reperfusion of the donor liver (P < 0.05) during liver transplantation, although levels were not lower in patients than in control subjects. 3. Pre-reperfusion antioxidant capacity correlated negatively with the concentration of lipid peroxidation products appearing in the plasma by the end of the transplant (P < 0.02), but did not correlate with vitamin A or E concentrations. 4. This study provides evidence of oxidant stress during liver transplantation, as shown by antioxidant utilization associated with increased lipid peroxidation.

The effect of anticoagulant choice on apparent total antioxidant capacity using three different methods

We assessed total antioxidant capacity using three different methods, in plasma samples treated with either EDTA or heparin as anticoagulant, from 26 healthy subjects. Total antioxidant capacity was determined using an oxygen electrode (as the total peroxyl radical-trapping antioxidant parameter), by enhanced chemiluminescence, and by measurement of the antioxidant-mediated quenching of the absorbance of a radical cation. The choice of anticoagulant had a profound effect on antioxidant capacity with heparinized plasma giving consistently higher values than plasma anticoagulated with EDTA. Using the oxygen electrode the mean value was 786.5 +/- 171.5 mumol/L (heparin) compared to 681.4 +/- 160.4 mumol/L (EDTA, P < 0.01). The chemiluminescence technique gave a mean antioxidant capacity of 915.6 +/- 214.1 mumol/L in heparin samples and 714.4 +/- 195.4 mumol/L in EDTA samples (P < 0.0001). The absorbance quenching technique gave a mean value of 867.0 +/- 199.2 mumol/L (heparin) and 675.5 +/- 245.4 mumol/L (EDTA, P < 0.001). All methods tested showed comparable results for EDTA plasma, but the chemiluminescence technique gave higher apparent antioxidant capacity than either of the two techniques when heparin plasma was used. We suggest that either heparin is interacting to enhance antioxidant protection perhaps through release of superoxide dismutase, or the chelation of metal ions by EDTA is limiting the activity of antioxidant metalloenzymes. Consistency in the choice of anticoagulant is clearly extremely important.

Multi-generational carcinogenesis from diethylstilbestrol investigated by blastocyst transfers in mice

Previous studies have shown that a carcinogenic effect can be transmitted from female mice exposed prenatally to diethylstilbestrol (DES) to their female offspring. Furthermore, male mice exposed pre-natally to DES can transmit a carcinogenic effect to their offspring through their germ cells. To study how multi-generational carcinogenesis is transmitted through females exposed pre-natally to DES, the technique of blastocyst transfer was utilized. Blastocysts from strain CD-1 mice exposed pre-natally to vehicle were transferred to mice exposed pre-natally to DES. Among 143 offspring from these transfers, there were 10 ovarian adenomas and 10 uterine adenocarcinomas. Among 92 offspring from blastocyst transfers between mice exposed pre-natally to vehicle only, there was 1 ovarian adenoma and 1 uterine adenocarcinoma. Thus the pre-natal exposure of the host to DES produced a maternal environment which increased the incidence of ovarian and uterine tumors. The reverse type of transfer was also performed, in which blastocysts from female mice exposed pre-natally to DES were transferred into mice exposed to vehicle only pre-natally. Among 99 offspring derived from DES-exposed germ cells, 6 developed ovarian adenomas and 16 developed uterine adenocarcinomas. Thus DES also has a multi-generational effect transmitted through the blastocyst, which is consistent with fetal germ cell mutation from DES.

Decreased antioxidant status and increased lipid peroxidation in patients with septic shock and secondary organ dysfunction

OBJECTIVE

To determine antioxidant vitamin concentrations, lipid peroxidation, and an index of nitric oxide production in patients in the intensive care unit (ICU) with septic shock and relate the findings to the presence of secondary organ failure.

DESIGN

A prospective, observational study.

SETTING

A nine-bed ICU in a University teaching hospital.

PATIENTS

Sixteen consecutive patients with septic shock, defined as: a) clinical evidence of acute infection; b) hypo- or hyperthermia (< 35.6 degrees C or > 38.3 degrees C); c) tachypnea (> 20 breaths/min or being mechanically ventilated); d) tachycardia (> 90 beats/min); e) shock (systolic pressure < 90 mm Hg) or receiving inotropes. Fourteen patients also had secondary organ dysfunction.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Antioxidant vitamin concentrations were significantly lower in the patients than the reference range obtained from a comparable group of healthy controls. The mean plasma retinol (vitamin A) concentration was 26.5 +/- 19.3 micrograms/dL compared with 73.5 +/- 18.3 micrograms/dL in healthy subjects (p < .01). Additionally, 13 (81%) patients had retinol values below the lower limit of our reference range (< 37.0 micrograms/dL). Tocopherol (vitamin E) plasma concentrations were below the reference range in all patients (< 9.0 mg/L), with a mean value of 3.6 +/- 2.0 mg/L compared with 11.5 +/- 1.3 mg/L in healthy subjects (p < .001). Plasma beta carotene and lycopene concentrations were undetectable (< 15 micrograms/L) in eight (50%) patients, and below our reference range (< 101 micrograms/L and < 154 micrograms/L, respectively) in the remaining patients. In the five patients with three or more dysfunctional secondary organs, plasma thiobarbituric acid-reactive substances were significantly increased (p < .05), suggesting increased lipid peroxidation. Concentrations of thiobarbituric acid-reactive substances correlated negatively with both plasma retinol and plasma tocopherol (r2 = .42, p < .01 and r2 = .48, p < .005, respectively). In the five patients from whom we were able to collect urine, nitrite excretion was increased approximately 400-fold (p < .001).

CONCLUSIONS

These data indicate decreased antioxidant status in the face of enhanced free radical activity, and suggest potential therapeutic strategies involving antioxidant repletion.

Nitric oxide synthase activity is increased in patients with sepsis syndrome

1. We measured nitric oxide synthase activity in peripheral blood polymorphonuclear leucocytes from 10 patients with sepsis syndrome and 10 healthy subjects. 2. Synthase activity was significantly higher in patients with sepsis than in control subjects (1202 +/- 579 compared with 595 +/- 544 pmol of nitric oxide min-1 mg-1 of cell protein, P < 0.05). 3. Activity was greatest in those patients with the larger number of organ failures, although this failed to reach significance (1489 +/- 560 in patients with three or more organ failures and 843 +/- 404 pmol of nitric oxide min-1 mg-1 of cell protein in those with less than three, P = 0.11). 4. This study provides evidence for the role of overproduction of the vasodilator nitric oxide in sepsis syndrome.

Nitric oxide production by human peripheral blood polymorphonuclear leucocytes

1. We describe a rapid and reliable technique for the assessment of basal nitric oxide release in clinical situations, using peripheral blood polymorphonuclear leucocytes isolated by a single-step density gradient procedure. The assay is based on the quantitative conversion of oxyhaemoglobin to methaemoglobin by nitric oxide. We have further examined the ability of these cells to respond to various stimuli. 2. Basal (unstimulated) nitric oxide release occurred, which was augmented by superoxide dismutase. The mean value for healthy subjects was 283 +/- 96.7 pmol min-1 10(-6) cells. 3. Both phorbol myristate acetate and N-formyl-methionyl-leucylphenylalanine induced further release of nitric oxide, which was increased by preincubation with lipopolysaccharide, interleukin-6 and interferon-gamma. 4. Preincubation of cells with NG-monomethyl-L-arginine or L-canavanine sulphate inhibited nitric oxide production. 5. The procedure provides a valuable tool for monitoring nitric oxide up-regulation in clinical situations.

Reperfusion injury, antioxidants and hemodynamics during orthotopic liver transplantation

Endothelial injury occurs as a result of oxygen free radical production after ischemia and reperfusion of transplanted livers, causing hemodynamic disturbance. Patients with chronic liver disease generally have low levels of fat-soluble vitamins, which have important antioxidant roles. We therefore assessed circulating levels of the antioxidants vitamin A, vitamin E, beta-carotene and lycopene, indices of lipid peroxidation and hemodynamic changes during elective orthotopic liver transplantation in 12 patients. We found that initial antioxidant levels were severely depleted compared with healthy subjects, and in some patients carotene and lycopene levels were undetectable. Increased lipid peroxidation was also evident, as shown by thiobarbituric acid-reactive substances. On reperfusion of the liver graft, vitamin A and E levels fell (p < 0.01) and were associated with decreases in systemic vascular resistance (p < 0.02). These data show that patients undergoing liver transplant have lowered antioxidant defenses and evidence of free radical damage, which compound the additional insult of reperfusion injury. Antioxidant therapy in these patients before transplantation may ameliorate the effects of reperfusion.

Potentiation of triamcinolone-induced cleft palate in mice by maternal high dietary fat

This study investigated whether the current range in dietary fat levels, which has arisen partly in response to some major health concerns, would affect frequency of congenital anomalies if continued into the period of early pregnancy. The effect of 5.6%, or 48% of calories from fat in the maternal diet, was tested on pregnant strain CD-1 mice injected with triamcinolone in doses of 0.01 mg, 0.02 mg, 0.04 mg, or 0.06 mg per day on days 11 through 14 of gestation. Frequency of cleft palate increased with increasing doses of triamcinolone, with clefts of the palate being rare at the two lower doses. No clefts appeared without triamcinolone on either diet. In combination with triamcinolone treatment, 226 fetuses exposed to a maternal low fat diet had normal palates and 86 had cleft palates. With exposure to high fat, 186 fetuses had normal palates and 101 had cleft palates, which was a significant increase in clefting (p < 0.05). Also, the latter group showed a greater degree of retardation in palate development (p < 0.05). Thus both a greater frequency and a more severe form of clefting support the conclusion that high dietary fat potentiated the cleft palate-producing effects of triamcinolone in mice.

Pituitary tumors in mice exposed prenatally to diethylstilbestrol

Hyperprolactinemia and prolactinomas are among the abnormalities reported for women exposed prenatally to diethylstilbestrol (DES). To pursue this issue in an animal model replicating the other abnormalities of prenatal DES exposure, pituitary glands were studied in the offspring of CD-1 mice receiving an i.p. injection of 1 or 2 micrograms DES/g body weight during late pregnancy. Among 132 mice exposed prenatally to DES and then raised to terminal illness, there were 24 pituitary tumors compared to only 1 tumor among 64 controls. The tumors consisted predominantly of cells with an eccentric nucleus and cytoplasm characterized by an acidophilic core and basophilic rim. These cells were identified as lactotrophs on the basis of prolactin immunohistochemistry and by an expected variation in frequency relative to physiological states. Evaluation of ovaries from the same mice revealed a deficiency of corpora lutea and an elevated incidence of ovarian tumors. These findings are consistent with abnormal sex differentiation of the fetal hypothalamus being the cause of most adverse effects from prenatal DES exposure.

Correction of cellular zinc depletion by oral zinc supplementation in elderly subjects

Immune function declines with age, and has been implicated in the increased incidence of cancer and infections in the elderly. In this hospital, many elderly patients have evidence of zinc depletion. In the present study, we supplemented those elderly patients who had depressed polymorphonuclear cell (PMNC) zinc levels with 135 mg oral zinc sulphate for 4 weeks. Plasma and PMNC zinc increased markedly but the percentage of peripheral blood T-lymphocytes expressing the surface markers CD3, CD4 and CD8 were unchanged. Plasma concentrations of vitamins A and E also remained constant. This study confirms the 25-30% incidence of cellular zinc depletion in this patient population, and demonstrates that zinc concentrations can be brought back to within normal limits by oral zinc supplements, but with no effect on T-cell phenotypes.

Early diagnosis of ectopic arginine vasopressin secretion

We describe a patient who presented with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) 2 months before clinical evidence of bronchogenic malignancy. Because of the potential for the ectopic production of atrial natriuretic peptide (ANP) to mimic SIADH, both hormones were measured in this hyponatremic patient to seek a possible marker of tumor activity. A hypertonic saline infusion at presentation revealed excessive osmotically decoupled secretion of arginine vasopressin but a normal ANP response.

Early diagnosis of ectopic arginine vasopressin secretion

We describe a patient who presented with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) 2 months before clinical evidence of bronchogenic malignancy. Because of the potential for the ectopic production of atrial natriuretic peptide (ANP) to mimic SIADH, both hormones were measured in this hyponatremic patient to seek a possible marker of tumor activity. A hypertonic saline infusion at presentation revealed excessive osmotically decoupled secretion of arginine vasopressin but a normal ANP response.

Evidence of hypothalamic involvement in the mechanism of transplacental carcinogenesis by diethylstilbestrol

Disruption of hypothalamic sex differentiation in the fetus is one hypothesis to explain female reproductive system anomalies and cancer arising from prenatal exposure to diethylstilbestrol (DES). To further test this hypothesis, breeding performance and behavior were monitored in a colony of mice exposed prenatally to DES, using a schedule previously shown to produce anomalies and cancer of the female reproductive system. Fertility decreased with age more rapidly in DES-exposed females than in control females. DES-exposed females were less accepting of the male than control females. These observations support the hypothesis of abnormal hypothalamic sex differentiation as a basic mechanism in DES transplacental carcinogenesis.

Vitamin C depletion and pressure sores in elderly patients with femoral neck fracture

OBJECTIVE

To evaluate the contribution of specific nutritional deficiencies (as indicated by zinc; vitamin A, C, and E; albumin; and haemoglobin concentrations) to the risk of pressure sores.

DESIGN

Observational cohort study.

SETTING

St James's University Hospital, Leeds.

SUBJECTS

21 elderly patients presenting consecutively to the orthopaedic unit with femoral neck fracture.

MAIN OUTCOME MEASURE

Full thickness epidermal break over a pressure bearing surface.

RESULTS

10 patients (48%) developed a pressure sore during their hospital stay. Indices of zinc status and concentrations of albumin, haemoglobin, and vitamins A and E were similar in patients who developed a pressure sore and those who did not. Mean leucocyte vitamin C concentration, however, was 6.3 (SD 2.2) micrograms/10(8) cells in patients who developed a pressure sore as compared with 12.8 (4.6) micrograms/10(8) cells in patients who did not.

CONCLUSIONS

Low concentrations of leucocyte vitamin C appear to be associated with subsequent development of pressure sores in elderly patients with femoral neck fractures.

Symptomatic zinc deficiency in experimental zinc deprivation

An evaluation of indices of poor zinc status was undertaken in five male subjects in whom dietary zinc intake was reduced from 85 mumol d-1 in an initial phase of the study to 14 mumol d-1. One of the subjects developed features consistent with zinc deficiency after receiving the low zinc diet for 12 days. These features included retroauricular acneform macullo-papular lesions on the face, neck, and shoulders and reductions in plasma zinc, red blood cell zinc, neutrophil zinc and plasma alkaline phosphatase activity. Alcohol induced hepatitis, which was suspected in this subject, may have caused a predisposition to altered zinc metabolism and possible zinc deficiency which was exacerbated by subsequent zinc deprivation. The report supports the value of neutrophil zinc concentration as an indicator of poor zinc status.

No effect of adult dietary fat on tumors induced prenatally by diethylstilbestrol

Strain CD-1 female mice exposed prenatally to diethylstilbestrol (DES) or vehicle were placed on semipurified diets containing 2.6%, 10%, 20%, or 29% fat by weight at four weeks of age. These mice were used as a breeding colony for a few weeks and then maintained to terminal illness on the semipurified diets. Females exposed prenatally to DES developed mammary tumors, pituitary tumors, and glandular tumors of the reproductive tract. There was no significant difference in tumor frequency between low- and high-fat dietary groups. Fewer tumors appeared in the vehicle-exposed mice, as expected, and their frequency did not differ between the dietary groups. Pregnancy reduced tumor frequency in DES-exposed mice, but the incidence of pregnancy was not significantly different between low- and high-fat dietary groups. In the adult the failure of a high-fat diet to increase the frequency of reproductive system tumors induced prenatally is in marked contrast to the effectiveness of high-fat diets in promoting mammary tumors induced by carcinogens given to rats postnatally. This difference is critical in the interpretation of epidemiological studies. The relationship of dietary fat to reproductive system cancer in human populations was reviewed in comparison with these two animal models. The epidemiological literature was found to be more consistent with the animal model, showing high sensitivity to dietary fat prenatally but no significant sensitivity at the adult stage of life.

Case report: hepatobronchial fistula complicating amoebiasis, treated by percutaneous catheter drainage

We report the case of a 41-year-old man who presented with hepatic amoebiasis 18 months after visiting the Far East. His progress was initially complicated by a bronchohepatic fistula which was further complicated by secondary bacterial infection. The fistula persisted and only resolved following percutaneous catheter drainage, thereby avoiding open surgery.

Effect of fasting, self-selected and isocaloric glucose and fat meals and intravenous feeding on plasma zinc concentrations

This study investigated the effect of fasting, self-selected meals and isocaloric oral glucose and fat meals and intravenous (i.v.) feeding on plasma zinc concentrations in men. Plasma zinc remained stable when volunteers fasted all day, but self-selected meals and 600 kCal of dextrose or fat emulsion caused significantly reduced plasma zinc concentrations [mean (SD) 12.1 (1.4), 12.3 (0.6) and 12.2 (0.7) mumol/L at 1400 h, respectively, compared with a fasting level of 13.9 (1.6) mumol/L at 0800 h, P less than 0.05]. In patients undergoing intravenous hyperalimentation, plasma zinc decreased from 12.0 (1.4) mumol/L at 0800 h to 10.0 (1.1) mumol/L at 1400 h [mean (SD), P less than 0.01]. These data show that both enteral and i.v. feeding cause a decline in plasma zinc and that glucose alone is not responsible for this post-prandial fall since ingestion of isocaloric amounts of glucose or fat have a similar effect.

Evidence of cellular zinc depletion in hospitalized but not in healthy elderly subjects

Cellular immune function declines with age and is implicated in the increased incidence of cancer, and morbidity and mortality associated with infections in elderly people. Elderly people are at risk of nutritional depletion, including of zinc, and zinc is known to influence immunity. The present study assessed zinc status in both healthy elderly subjects and elderly inpatients. Polymorphonuclear-cell zinc was decreased in the hospitalized subjects and 27% had values below the reference range for healthy elderly and young subjects. Since PMNC zinc is decreased in experimental zinc depletion and correlates with muscle zinc, we suggest that 27% of the patients studied may be zinc depleted and may benefit from zinc supplementation.

Venepuncture for calcium assays: should we still avoid tourniquet?

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Monocyte zinc and in vitro prostaglandin E2 and interleukin-1 beta production by cultured peripheral blood monocytes in patients with Crohn's disease

This study investigated the relationship between zinc status and prostaglandin E2 and interleukin-1 beta production by cultured monocytes in patients with Crohn's disease. Monocyte zinc was significantly decreased in both 12 inpatients and 22 outpatients compared with controls (P less than 0.001) but lymphocyte and polymorphonuclear cell zinc were normal. When cultured monocytes from 10 outpatients with Crohn's disease were stimulated with lipopolysaccharide, prostaglandin E2 production increased markedly, coupled with a fall in monocyte zinc. In matched controls, prostaglandin E2 production was significantly less and monocyte zinc remained stable. No difference in interleukin-1 release was noted between patients and controls. The addition of prednisolone to cell cultures suppressed prostaglandin E2, interleukin-1 synthesis, and monocyte zinc did not change. Zinc chloride augmented prostaglandin E2 production in patients, but not controls, and interleukin-1 remained stable. These results demonstrate a link between low monocyte zinc concentration and excessive prostaglandin production in patients with Crohn's disease.

The effects of acute infection on indices of zinc status

Various indices of zinc status were assessed in 12 patients with acute urinary tract or chest infections on Day 1 and Day 7 of the infection. Leucocyte counts were raised on Day 1 but had returned to near normal by Day 7. Plasma zinc was decreased on Day 1 in conjunction with depressed plasma albumin concentrations (r = 0.71, p < 0.001) but both had returned to normal by Day 7. Mononuclear cell zinc was raised in all patients on Day 1 compared to Day 7 and control values, but polymorphonuclear cell zinc remained unchanged. However, polymorphonuclear cell alkaline phosphatase activity was grossly increased on Day 1 and correlated with leucocyte count (r = 0.61, p < 0.01). Plasma alkaline phosphatase activity was variable. These results indicate that in patients with infections measurement of plasma mononuclear cell zinc concentration and alkaline phosphatase activity are misleading indicators of zinc status. Polymorphonuclear cell zinc is unaffected by leucocytosis, inflammation and stress and may therefore provide a more reliable index of zinc status in such patients.

Cellular and muscle zinc in surgical patients with and without gastrointestinal cancer

1. The zinc status of surgical patients with and without gastrointestinal cancer was studied. 2. Plasma zinc was lowest in patients with cancer concurrent with depressed plasma albumin concentrations. 3. Polymorphonuclear cell zinc was decreased in both patient groups and correlated strongly with abdominal muscle zinc (r = 0.89, P less than 0.001). 4. Mononuclear cell and total leucocyte zinc were similar to control values in both groups of patients. Total leucocyte, but not mononuclear cell, zinc correlated weakly with muscle zinc (r = 0.48, P less than 0.05). 5. The results suggest that polymorphonuclear cell zinc may be better than leucocyte zinc in assessing zinc status and that some surgical patients may be zinc-depleted. The presence of gastrointestinal cancer did not influence the zinc status.

Relation between zinc status and hepatic functional reserve in patients with liver disease

Patients with liver disease may be at risk of zinc depletion. We measured polymorphonuclear cell, mononuclear cell, plasma, and erythrocyte zinc values, and erythrocyte carbonic anhydrase activity to assess zinc status in 17 patients with non-alcoholic liver disease (primary biliary cirrhosis and chronic active hepatitis) and 13 patients with alcoholic liver disease. The plasma zinc concentration was reduced in both patient groups and correlated strongly with the plasma albumin concentration. The mean polymorphonuclear cell zinc value in both groups was similar to that of controls but when results were combined and grouped according to hepatic functional reserve, patients with more severe liver damage (grade C) had a lower polymorphonuclear cell zinc value (mean (SD) 0.86 (0.24) nmol/mg protein) than patients with grade A (1.44 (0.43) nmol/mg protein, p less than 0.01) or grade B liver damage (1.08 (0.30) nmol/mg protein, p less than 0.05), or control subjects (1.26 (0.28) nmol/mg protein, p less than 0.001). The polymorphonuclear cell zinc value did not correlate with other indices of zinc status. The mononuclear cell zinc value was normal in all patients and was unrelated to hepatic damage. The erythrocyte zinc value and carbonic anhydrase activity were raised in alcoholic patients only. Since the polymorphonuclear cell zinc concentration is low in human experimental zinc deficiency and also correlates with tissue zinc, we suggest that our results provide evidence of progressive leucocyte zinc depletion in patients with liver disease.

Tumors in female offspring of control and diethylstilbestrol-exposed mice fed high-fat diets

Strong correlations have been established internationally between female reproductive system cancer rates and dietary fat. To test the hypothesis that the prenatal period is a critical time for exposure to high dietary fat, we placed adult female strain CD-1 mice with or without prenatal exposure to diethylstilbestrol (DES) on diets with low or high levels of fat and mated them. After delivery of the litters, these mice were given the commercial diet on which they had been raised. Their female offspring were raised on this commercial diet until terminal illness occurred. Of the 47 offspring of control mice on low-fat diets, only five had reproductive system tumors, whereas tumors developed in 39 of 78 offspring of mice on high-fat diets. For DES-exposed mice, tumors developed in 18 of 64 offspring of mice on low-fat diets and 38 of 70 offspring of mice on high-fat diets. Nine mice with metastatic mammary tumors and seven with pituitary tumors were offspring of mice on high-fat diets.