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Providing adequate staff during a pandemic requires the creative use of all human resources from within the organization and from outside agencies offering assistance. With the use of all possible resources, clinical RNs are better supported at the bedside as they provide safe patient care. Defined processes provide clear information to staff regarding available human resources and their appropriate use., (2020 by Elsevier Inc. All rights reserved.)

Premise: Despite the fast pace of exploration of the patterns and processes influencing Neotropical plant hyperdiversity, the taxa explored are mostly from large groups that are widely distributed, morphologically diverse, or economically important. Vochysiaceae is an example of an undersampled taxon, providing an excellent system for investigating Neotropical biogeography. We present a phylogenomics-based hypothesis of species relationships in Vochysiaceae to investigate its evolutionary history through space and time., Methods: We inferred a phylogeny for 122 species from Vochysiaceae and seven other families of Myrtales. Fossils from four myrtalean families were used to estimate the divergence times within Vochysiaceae. Historical biogeography was estimated using ancestral range probabilities and stochastic mapping., Results: Monophyly of all genera was supported except for Qualea, which was split by Ruizterania into two clades. Vochysiaceae originated ~100 mya, splitting into an Afrotropical and a Neotropical lineage ~50 mya, and its ancestral range is in the area currently occupied by the Cerrado., Conclusions: The most recent common ancestor of Vochysiaceae + Myrtaceae had a West Gondwanan distribution, supporting a South American + African ancestral range of Vochysiaceae. On a global scale, geographic range reduction was the principal biogeographic event. At a finer scale, initial range reduction was also important and the Cerrado region was the most ancestral area with multiple colonization events to the Amazon, Central America, and the Atlantic Forest. Colonization events occurred from open areas to forest vegetation, an unusual finding regarding the evolution of plants in the Neotropics., (© 2020 Botanical Society of America.)

Seasonal variation in the availability of floral hosts or pollinators is a key factor influencing diversity in plant-pollinator communities. In seasonally dry Neotropical habitats, where month-long periods of extreme drought are followed by a long rainy season, flowering is often synchronized with the beginning of precipitation, when environmental conditions are most beneficial for plant reproduction. In the Brazilian Cerrado, a seasonally dry ecosystem considered one of the world's biodiversity hotspots for angiosperms, plants with shallow root systems flower predominantly during the rainy season. Foraging activity in social bees however, the major pollinators in this biome, is not restricted to any particular season because a constant supply of resources is necessary to sustain their perennial colonies. Despite the Cerrado's importance as a center of plant diversity, the influence of its extreme cycles of drought and precipitation on the dynamics and stability of plant-pollinator communities is not well understood. We sampled plant-pollinator interactions of a Cerrado community weekly for one year and used network analyses to characterize intra-annual seasonal variation in community structure. We also compared seasonal differences in community robustness to species loss by simulating extinctions of plants and pollinators. We find that the community shrinks significantly in size during the dry season, becoming more vulnerable to disturbance due to the smaller pool of floral hosts available to pollinators during this period. Major changes in plant species composition but not in pollinators has led to high levels of turnover in plant-pollinator associations across seasons, indicated by in interaction dissimilarity (<3% of shared interactions). Aseasonal pollinators, which mainly include social bees and some solitary specialized bees, functioned as keystone species, maintaining robustness during periods of drastic changes in climatic conditions., Competing Interests: The authors have declared that no competing interests exist.

The current classification of angiosperms is based primarily on concatenated plastid markers and maximum likelihood (ML) inference. This approach has been justified by the assumption that plastid DNA (ptDNA) is inherited as a single locus and that its individual genes produce congruent trees. However, structural and functional characteristics of ptDNA suggest that plastid genes may not evolve as a single locus and are experiencing different evolutionary forces. To examine this idea, we produced new complete plastid genome (plastome) sequences of 27 species and combined these data with publicly available sequences to produce a final dataset that includes 78 plastid genes for 89 species of rosids and five outgroups. We used four data matrices (i.e., gene, exon, codon-aligned, and amino acid) to infer species and gene trees using ML and multispecies coalescent (MSC) methods. Rosids include about one third of all angiosperms and their two major clades, fabids and malvids, were recovered in almost all analyses. However, we detected incongruence between species trees inferred with different matrices and methods and previously published plastid and nuclear phylogenies. We visualized and tested the significance of incongruence between gene trees and species trees. We then measured the distribution of phylogenetic signal across sites and genes supporting alternative placements of five controversial nodes at different taxonomic levels. Gene trees inferred with plastid data often disagree with species trees inferred using both ML (with unpartitioned or partitioned data) and MSC. Species trees inferred with both methods produced alternative topologies for a few taxa. Our results show that, in a phylogenetic context, plastid protein-coding genes may not be fully linked and behaving as a single locus. Furthermore, concatenated matrices may produce highly supported phylogenies that are discordant with individual gene trees. We also show that phylogenies inferred with MSC are accurate. We therefore emphasize the importance of considering variation in phylogenetic signal across plastid genes and the exploration of plastome data to increase accuracy of estimating relationships. We also support the use of MSC with plastome matrices in future phylogenomic investigations., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Phylogenomics has become increasingly popular in recent years mostly due to the increased affordability of next generation sequencing techniques. Phylogenomics has sparked interest in multiple fields of research, including systematics, ecology, epidemiology, and even personalized medicine, agriculture and pharmacy. Despite this trend, it is usually difficult to learn and understand how the analyses were done, how the results were obtained, and most importantly, how to replicate the study. Here we present the data and all of the code utilized to perform phylogenomic inferences using plastome data: from raw data to extensive phylogenetic inference and accuracy assessment. The data presented here utilizes plastome sequences available on GenBank (accession numbers of 94 species are available below) and the code is also available at https://github.com/deisejpg/rosids. Gonçalves et al. is the research article associated with the data analyses presented here.

Background and Aims: Natural enemies are known to be important in regulating plant populations and contributing to species coexistence (Janzen-Connell effects). The strength of Janzen-Connell effects (both distance- and density-effects) varies across species, but the life history traits that may mediate such a variation are not well understood. This study examined Janzen-Connell effects across the life stages (seed through adult stages) of two sympatric palm species with distinct phenologies and shade tolerances, two traits that may mediate the strength and timing of Janzen-Connell effects., Methods: Populations of two common palm species, Attalea phalerata and Astrocaryum murumuru , were studied in Manu National Park, Peru. Seed predation experiments were conducted to assess Janzen-Connell effects at the seed stage. In the post-seed stages, spatial point pattern analyses of the distributions of individuals and biomass were used to infer the strength of distance- and density-effects., Key Results: Seed predation was both negative distance- and density-dependent consistent with the Janzen-Connell effects. However, only seedling recruitment for asynchronously fruiting Attalea phalerata was depressed near adults while recruitment remained high for synchronously fruiting Astrocaryum murumuru , consistent with weak distance-effects. Negative density-effects were strong in the early stages for shade-intolerant Attalea phalerata but weak or absent in shade-tolerant Astrocaryum murumuru., Conclusions: Distance- and density-effects varied among the life stages of the two palm species in a manner that corresponded to their contrasting phenology and shade tolerance. Generalizing such connections across many species would provide a route to understanding how trait-mediated Janzen-Connell effects scale up to whole communities of species., (© The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

High-throughput sequencing is helping biologists to overcome the difficulties of inferring the phylogenies of recently diverged taxa. The present study analyzes the phylogenetic signal of genomic regions with different inheritance patterns using genome skimming and ddRAD-seq in a species-rich Andean genus (Diplostephium) and its allies. We analyzed the complete nuclear ribosomal cistron, the complete chloroplast genome, a partial mitochondrial genome, and a nuclear-ddRAD matrix separately with phylogenetic methods. We applied several approaches to understand the causes of incongruence among datasets, including simulations and the detection of introgression using the D-statistic (ABBA-BABA test). We found significant incongruence among the nuclear, chloroplast, and mitochondrial phylogenies. The strong signal of hybridization found by simulations and the D-statistic among genera and inside the main clades of Diplostephium indicate reticulate evolution as a main cause of phylogenetic incongruence. Our results add evidence for a major role of reticulate evolution in events of rapid diversification. Hybridization and introgression confound chloroplast and mitochondrial phylogenies in relation to the species tree as a result of the uniparental inheritance of these genomic regions. Practical implications regarding the prevalence of hybridization are discussed in relation to the phylogenetic method., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)

Nurse managers are instrumental in achievement of organizational and unit performance goals. Greater spans of control for managers are associated with decreased satisfaction and performance. An interprofessional team measured one organization's nurse manager span of control, providing administrative assistant support and transformational leadership development to nurse managers with the largest spans of control. Nurse manager satisfaction and transformational leadership competency significantly improved following the implementation of large span of control mitigation strategies.

The idiosyncratic behaviours of seed dispersers are important contributors to plant spatial associations and genetic structures. In this study, we used a combination of field, molecular and spatial studies to examine the connections between seed dispersal and the spatial and genetic structures of a dominant neotropical palm Attalea phalerata. Field observation and genetic parentage analysis both indicated that the majority of A. phalerata seeds were dispersed locally over short distances (<30 m from the maternal tree). Spatial and genetic structures between adults and seedlings were consistent with localized and short-distance seed dispersal. Dispersal contributed to spatial associations among maternal sibling seedlings and strong spatial and genetic structures in both seedlings dispersed near (<10 m) and away (>10 m) from maternal palms. Seedlings were also spatially aggregated with juveniles. These patterns are probably associated with the dispersal of seeds by rodents and the survival of recruits at specific microsites or neighbourhoods over successive fruiting periods. Our cross-cohort analyses found palms in older cohorts and cohort pairs were associated with a lower proportion of offspring and sibling neighbours and exhibited weaker spatial and genetic structures. Such patterns are consistent with increased distance- and density-dependent mortality over time among palms dispersed near maternal palms or siblings. The integrative approaches used for this study allowed us to infer the importance of seed dispersal activities in maintaining the aggregated distribution and significant genetic structures among A. phalerata palms. We further conclude that distance- and density-dependent mortality is a key postdispersal process regulating this palm population., (© 2012 Blackwell Publishing Ltd.)

Background and Aims: Most Neotropical species of Malpighiaceae produce floral fatty oils in calyx glands to attract pollinating oil-collecting bees, which depend on this resource for reproduction. This specialized type of pollination system tends to be lost in members of the family that occur outside the geographic distribution (e.g. Africa) of Neotropical oil-collecting bees. This study focused on the pollination ecology, chemical ecology and reproductive biology of an oil flower species, Pterandra pyroidea (Malpighiaceae) from the Brazilian Cerrado. Populations of this species consist of plants with oil-secreting (glandular) flowers, plants with non-oil-secreting flowers (eglandular) or a mix of both plant types. This study specifically aims to clarify the role of eglandular morphs in this species., Methods: Data on pollinators were recorded by in situ observations. Breeding system experiments were conducted by isolating inflorescences and by enzymatic reactions. Floral resources, pollen and floral oils offered by this species were analysed by staining and a combination of various spectroscopic methods., Key Results: Eglandular flowers of P. pyroidea do not act as mimics of their oil-producing conspecifics to attract pollinators. Instead, both oil-producing and oil-free flowers depend on pollen-collecting bees for reproduction, and their main pollinators are bumble-bees. Floral oils produced by glandular flowers are less complex than those described in closely related genera., Conclusions: Eglandular flowers represent a shift in the pollination system in which oil is being lost and pollen is becoming the main reward of P. pyroidea flowers. Pollination shifts of this kind have hitherto not been demonstrated empirically within Neotropical Malpighiaceae and this species exhibits an unusual transition from a specialized towards a generalized pollination system in an area considered the hotspot of oil-collecting bee diversity in the Neotropics. Transitions of this type provide an opportunity to study ongoing evolutionary mechanisms that promote the persistence of species previously involved in specialized mutualistic relationships.

The sunflower genus, Helianthus, is recognized widely for the cultivated sunflower H. annuus and scientifically as a model organism for studying diploid and polyploid hybrid speciation, introgression, and genetic architecture. A resolved phylogeny for the genus is essential for the advancement of these scientific areas. In the past, phylogenetic relationships of the perennial species and polyploid hybrids have been particularly difficult to resolve. Using the external transcribed spacer region of the nuclear 18S-26S rDNA region, we reveal for the first time a highly resolved gene tree for Helianthus. Phylogenetic analysis allowed the determination of a monophyletic annual H. sect. Helianthus, a two-lineage polyphyletic H. sect. Ciliares, and the monotypic H. sect. Agrestis, all of which were nested within a large perennial and polyphyletic H. sect. Divaricati. The distribution of perennial polyploids and known annual diploid hybrids on this phylogeny suggested multiple independent hybrid speciation events that gave rise to at least four polyploids and three diploid hybrids. Also provided by this phylogeny was evidence for homoploid hybrid speciation outside H. sect. Helianthus. Finally, previous hypotheses about the secondary chemistry in the genus were tested in a phylogenetic framework to obtain a better understanding of the evolution of these compounds in Helianthus.

Expansion of the arid zone of sub-Saharan tropical Africa during the Miocene is posited as a significant contributing factor in the evolution of contemporary African flora. Nevertheless, few molecular phylogenetic studies have tested this hypothesis using reconstructed historical biogeographies of plants within this zone. Here, we present a molecular phylogeny of Commiphora, a predominantly tropical African, arid-adapted tree genus, in order to test the monophyly of its taxonomic sections and identify clades that will help direct future study of this species-rich and geographically widespread taxon. We then use multiple fossil calibrations of Commiphora phylogeny to determine the timing of well-supported diversification events within the genus and interpret these age estimates to determine the relative contribution of vicariance and dispersal in the expansion of Commiphora's geographic range. We find that Commiphora is sister to Vietnamese Bursera tonkinensis and that its crown group radiation corresponds with the onset of the Miocene.

We propose a phylogenetic hypothesis of relationships within Callandrena, a North American subgenus of the bee genus Andrena, based on both mitochondrial and nuclear DNA sequences. Our data included 695 aligned base pairs comprising parts of the mitochondrial genes cytochrome oxidase subunits I and II and the intervening tRNA-leucine and 767 aligned base pairs of the F2 copy of the nuclear gene elongation factor-1alpha. We also suggest a preliminary hypothesis of relationships of the North American subgenera in the genus. Our analyses included 54 species of Callandrena, 42 species of Andrena representing 24 additional subgenera, and 11 outgroup species in the family Andrenidae. Parsimony analyses of each marker separately suggested that Callandrena was polyphyletic, with a combined analysis suggesting that there were at least two phylogenetically independent clades of bees with similar morphological features. Maximum likelihood and Bayesian analyses supported this conclusion, as did the non-parametric bootstrapping SOWH test. Convergence in morphological characters was likely due to their common use of members of Asteraceae as pollen hosts.

Phylogenetic relationships among genera of tribe Malveae (Malvaceae, subfamily Malvoideae) were reconstructed using sequences of the internal transcribed spacer (ITS) region of the 18S-26S nuclear ribosomal repeat. Newly generated sequences were combined with those available from previous generic level studies to assess the current circumscription of the tribe, monophyly of some of the larger genera, and character evolution within the tribe. The ITS data do not support monophyly of most generic alliances as presently defined, nor do the data support monophyly of several Malveae genera. Two main well-supported clades were recovered, which correspond primarily to taxa that either possess or lack involucral bracts, respectively. Chromosomal evolution has been dynamic in the tribe with haploid numbers varying from n = 5 to 36. Aneuploid reduction, hybridization, and/or polyploidization have been important evolutionary processes in this group.

Generalized hypotheses for the vicariant, Gondwanan origin of pantropically distributed eudicotyledon families must be refined to accommodate recently revised dates that indicate major continental rifting events predate the evolution of many tricolpate angiosperm clades. Here, we use molecular phylogenies of an eudicotyledon family previously hypothesized to have a Gondwanan origin, the Burseraceae, to test this and other alternative biogeographical hypotheses in light of recalibrated geological events. Phylogenies based on nuclear and chloroplast data were reconstructed for 13 of the 18 genera (50 spp. total) of Burseraceae using parsimony, maximum likelihood, and Bayesian methods. Ages of all lineages were estimated using penalized likelihood and semiparametric rate smoothing [Bioinformatics 2003 (19) 301], which allows the user to calibrate phylogenies based on non-clock-like DNA sequence data with fossil information. Biogeographical hypotheses were tested by comparing ages of species and more inclusive lineages with their extant and most parsimonious ancestral distributions. Our data support a North American Paleocene origin for the Burseraceae followed by dispersal of ancestral lineages to eastern Laurasia and Southern Hemisphere continents.

Historically, genetic introgression among species as well as hybrid origins for species of the diploid tree genus Bursera (Burseraceae) have been proposed based on the supposition that individuals morphologically intermediate between sympatric "parent" species must be derived from hybridization. This study reports the first molecular genetic evidence for both unidirectional and reciprocal interspecific hybridization within Bursera. Phylogenies of hybrids and other species in B. subgenus Bursera are reconstructed based on nuclear and chloroplast sequence data. Compelling evidence supports the hybrid origin of three endemic Hispaniolan species: B. brunea (B. nashii × B. simaruba), B. gracilipes (B. spinescens × B. simaruba), and B. ovata (B. simaruba × B. spinescens). Cloning studies of nuclear markers from B. ovata suggests that this species is an introgressed or later backcross generation hybrid and thus reproduces sexually.

Polyploidy, primarily allopolyploidy, has played a major role throughout flowering plant evolution with an estimated 30-80% of all extant angiosperms carrying traces of ancient or recent polyploidy. One immediate and seemingly invariant phenotypic consequence of genome doubling is larger cell size in polyploids relative to their diploid progenitors. In plants, increases in pollen grain and guard cell sizes exemplify this rule and are often used as surrogate evidence for polyploidy. Tarasa (Malvaceae), a genus of 27 species primarily distributed in the high (>3000 m) Andes, has numerous independently generated tetraploid species, most of which have pollen grains smaller than their putative diploid parents. The tetraploids are also unusual because they are annual, rather than perennial, in habit. Data correlate these apparent anomalies to a change in the breeding system within the genus from xenogamy (outcrossing) in the diploid species to autogamy (inbreeding) in the tetraploids, leading to a convergence in reduced floral morphology. The harsh environment of the high-elevation Andean habitats in which all the tetraploid annuals are found is implicated as a critical factor in shaping the evolution of these unusual polyploids.

ActRIB is a type I transmembrane serine/threonine kinase receptor that has been shown to form heteromeric complexes with the type II activin receptors to mediate activin signal. To investigate the function of ActRIB in mammalian development, we generated ActRIB-deficient ES cell lines and mice by gene targeting. Analysis of the ActRIB-/- embryos showed that the epiblast and the extraembryonic ectoderm were disorganized, resulting in disruption and developmental arrest of the egg cylinder before gastrulation. To assess the function of ActRIB in mesoderm formation and gastrulation, chimera analysis was conducted. We found that ActRIB-/- ES cells injected into wild-type blastocysts were able to contribute to the mesoderm in chimeric embryos, suggesting that ActRIB is not required for mesoderm formation. Primitive streak formation, however, was impaired in chimeras when ActRIB-/- cells contributed highly to the epiblast. Further, chimeras generated by injection of wild-type ES cells into ActRIB-/- blastocysts formed relatively normal extraembryonic tissues, but the embryo proper developed poorly probably resulting from severe gastrulation defect. These results provide genetic evidence that ActRIB functions in both epiblast and extraembryonic cells to mediate signals that are required for egg cylinder organization and gastrulation.

A 7-week-old boy presented with a 6-week history of failure to thrive, acute intestinal obstruction, and an apparently irreducible intussusception (noted on contrast enema). He underwent abdominal exploration, during which a cecal mass was identified and resected. The mass proved to be a leiomyosarcoma. Histologically, it was an intermediate-grade malignancy with a predicted 5-year survival rate of 16% to 23% based on data from the adult experience. Three years after resection and without having received adjuvant therapy, he is healthy and free of disease. A review of the literature showed that in infants these tumors are predominantly colonic, compared with the predilection for small intestinal lesions found in the older pediatric and adult populations. Infantile intestinal leiomyosarcomata are rare malignancies that do well if complete surgical excision of the disease can be accomplished. The histological prognostic indicators proposed for intestinal leiomyosarcomas in the adult population cannot be extrapolated to infants because when they occur in infants, they appear to be less aggressive, and these patients do well without adjuvant therapy.

Complete laryngotracheoesophageal clefts (types III and IV) are rare congenital anomalies that occur when the primitive foregut fails to separate into the tracheobronchial tree and the esophagus. This article summarizes a 10-year institutional experience with six infants who had type IV clefts, presents a modification of the authors' surgical approach, and identifies pitfalls in the management of these infants. Three of the six children are long-term survivors. The recognition of specific complicating issues leads to a standardized approach, which can result in successful repair and long-term survival.

The study of ligand receptor interactions and receptor function often requires multifaceted experimental approaches. In the course of studying the function and mechanism of action of müllerian inhibiting substance (MIS), we have used a wide range of molecular and cellular techniques. These have led to the identification, cloning, and characterization of the MIS receptors and of other receptors for the transforming growth factor-beta (TGF beta) family. This article describes the use of polymerase chain reaction (PCR) cloning to isolate candidate receptor genes, transfection and flow cytometry to study ligand binding, nonhomologous recombination targeted gene disruption (knockout) to analyze receptor function, and yeast genetics to identify other proteins that interact with the receptor complex. Together these techniques have led to the development of therapeutics and therapeutic strategies that are ready for clinical application.

Chronic constipation is a common childhood problem that accounts for 3% to 5% of pediatric visits and 10% to 25% of referrals to pediatric gastroenterologists. The etiology of constipation can be elusive, and extensive investigation often fails to identify a specific cause. The authors conducted a 5-year retrospective review of the patients referred for deep transanal rectal biopsy to determine the usefulness of this procedure in the evaluation and subsequent surgical management of refractory constipation. Specimens obtained by transanal rectal biopsy established a diagnosis for 30 of the 70 patients, and 17 of these 30 had subsequent procedures in the treatment of their constipation. The authors conclude that transanal rectal biopsy identifies a significant number of patients with previously unidentified neuroenteric disorders who may benefit from additional surgery in the treatment of constipation refractory to medical management.

The association of species of yucca and their pollinating moths is considered one of the two classic cases of obligate mutualism between floral hosts and their pollinators. The system involves the active collection of pollen by females of two prodoxid moth genera and the subsequent purposeful placement of the pollen on conspecific stigmas of species of Yucca. Yuccas essentially depend on the moths for pollination and the moths require Yucca ovaries for oviposition. Because of the specificity involved, it has been assumed that the association arose once, although it has been suggested that within the prodoxid moths as a whole, pollinators have arisen from seed predators more than once. We show, by using phylogenies generated from three molecular data sets, that the supposed restriction of the yucca moths and their allies to the Agavaceae is an artifact caused by an incorrect circumscription of this family. In addition we provide evidence that Yucca is not monophyletic, leading to the conclusion that the modern Yucca-yucca moth relationship developed independently more than once by colonization of a new host.

Vogel's report of the production of glycerides rather than nectar as rewards gathered by bees described an association involving several genera of insects and numerous plant families. We report here that members of the Krameriaceae produce floral lips more unusual than those described by Vogel. Our data also provide evidence that the oils of Krameria are collected by bees of only one genus, Centris (Anthophoridae), and used, mixed with pollen, as larval food.

Analyses of the floras of the high north Andean habitat islands (paramos) and the Galápagos Islands show that plant species diversity conforms to the MacArthur and Wilson model of island biogeography but that immigration occurred primarily during glacial periods. Modern plant species diversity is more significantly correlated with area and distance measures of the glacial forms of the islands than with similar measures of the present-day islands.

A comparison of the floral syndromes, flower biomasses, pollen and total sugar production of the dominant perennial species of two climatically similar but disjunct desert scrub ecosystems was made to assess the degree of convergence in breeding systems. Results indicate that the dominants at the northern site in the Sonoran Desert near Tucson Arizona, USA, possess more diverse floral types, utilize more reproductive methods, produce a greater annual biomass of flowers, provide more rewards for potential pollinators and employ a wider array of pollen vectors than those at the southern site near Andalgalá, Catamarca, Argentina. The discrepancies in these features can be best explained in terms of the differences in the annual dispersion of rainfall at the two sites. However, when compared to the dominant species of two Mediterranean scrub ecosystems, the breeding systems of the dominants of the desert scrub sites proved to be more similar to one another than to those of a neighboring but different ecosystem type.

This study reports the first in vivo results using an MR contrast agent manganese dipyridoxal diphosphate (Mn-DPDP) designed to estimate the functional status of the hepatocyte. Thirty New Zealand white rabbits were studied in groups of 5 as follows: No. 1, control, MRI scans only; No. 2 MRI before and up to 90 min following 50 mumol/kg of Mn-DPDP iv; No. 3, rabbits received 9.3 g ethanol/kg and MRI; No. 4, as in No. 3 but following Mn-DPDP; No. 5, MRI as in No. 2 but 18 h. following 1000 mg/kg D-galactosamine used to induce hepatocyte necrosis; and No. 6, rabbits received D-galactosamine and MN-DPDP. In this study significant ethanol- and D-galactosamine-induced hepatocyte damage was indicated by the increased SGPt serum levels in the rabbit. The use of Mn-DPDP allowed detection of early hepatocyte necrosis in these animals whereas conventional spin-echo MRI did not. The fact that D-galactosamine curves with and without Mn-DPDP were not significantly different indicated virtually no membrane transport or metabolism of Mn-DPDP in the liver. Ethanol curves were not normal, but there was still considerable residual Mn-DPDP metabolism. Mn-DPDP appears to be an attractive agent in assessing hepatocyte function.