Multiscale physiological responses to nitrogen supplementation of maize hybrids

Maize (Zea mays) production systems are heavily reliant on the provision of managed inputs such as fertilizers to maximize growth and yield. Hence, the effective use of nitrogen (N) fertilizer is crucial to minimize the associated financial and environmental costs, as well as maximize yield. However, how to effectively utilize N inputs for increased grain yields remains a substantial challenge for maize growers that requires a deeper understanding of the underlying physiological responses to N fertilizer application. We report a multiscale investigation of five field-grown maize hybrids under low or high N supplementation regimes that includes the quantification of phenolic and prenyl-lipid compounds, cellular ultrastructural features, and gene expression traits at three developmental stages of growth. Our results reveal that maize perceives the lack of supplemented N as a stress and, when provided with additional N, will prolong vegetative growth. However, the manifestation of the stress and responses to N supplementation are highly hybrid-specific. Eight genes were differentially expressed in leaves in response to N supplementation in all tested hybrids and at all developmental stages. These genes represent potential biomarkers of N status and include two isoforms of Thiamine Thiazole Synthase involved in vitamin B1 biosynthesis. Our results uncover a detailed view of the physiological responses of maize hybrids to N supplementation in field conditions that provides insight into the interactions between management practices and the genetic diversity within maize.

Association mapping across a multitude of traits collected in diverse environments in maize

Classical genetic studies have identified many cases of pleiotropy where mutations in individual genes alter many different phenotypes. Quantitative genetic studies of natural genetic variants frequently examine one or a few traits, limiting their potential to identify pleiotropic effects of natural genetic variants. Widely adopted community association panels have been employed by plant genetics communities to study the genetic basis of naturally occurring phenotypic variation in a wide range of traits. High-density genetic marker data-18M markers-from 2 partially overlapping maize association panels comprising 1,014 unique genotypes grown in field trials across at least 7 US states and scored for 162 distinct trait data sets enabled the identification of of 2,154 suggestive marker-trait associations and 697 confident associations in the maize genome using a resampling-based genome-wide association strategy. The precision of individual marker-trait associations was estimated to be 3 genes based on a reference set of genes with known phenotypes. Examples were observed of both genetic loci associated with variation in diverse traits (e.g., above-ground and below-ground traits), as well as individual loci associated with the same or similar traits across diverse environments. Many significant signals are located near genes whose functions were previously entirely unknown or estimated purely via functional data on homologs. This study demonstrates the potential of mining community association panel data using new higher-density genetic marker sets combined with resampling-based genome-wide association tests to develop testable hypotheses about gene functions, identify potential pleiotropic effects of natural genetic variants, and study genotype-by-environment interaction.

Aureochromes maintain polyunsaturated fatty acid content in Nannochloropsis oceanica

Nannochloropsis oceanica, like other stramenopile microalgae, is rich in long-chain polyunsaturated fatty acids (LC-PUFAs) such as eicosapentaenoic acid (EPA). We observed that fatty acid desaturases (FADs) involved in LC-PUFA biosynthesis were among the strongest blue light-induced genes in N. oceanica CCMP1779. Blue light was also necessary for maintaining LC-PUFA levels in CCMP1779 cells, and growth under red light led to a reduction in EPA content. Aureochromes are stramenopile-specific proteins that contain a light-oxygen-voltage (LOV)-sensing domain that associates with a flavin mononucleotide and is able to sense blue light. These proteins also contain a basic leucine zipper DNA-binding motif and can act as blue light-regulated transcription factors by associating with an E-box like motif, which we found enriched in the promoters of blue light-induced genes. We demonstrated that, in vitro, two CCMP1779 aureochromes were able to absorb blue light. Moreover, the loss or reduction of the expression of any of the three aureochrome genes led to a decrease in the blue light-specific induction of several FADs in CCMP1779. EPA content was also significantly reduced in NoAUREO2 and NoAUREO4 mutants. Taken together, our results indicate that aureochromes mediate blue light-dependent regulation of LC-PUFA content in N. oceanica CCMP1779 cells.

1382 Retrospective Audit to Assess Compliance to National Guidance for The Follow-Up of Acute Uncomplicated Diverticulitis and Adenoma Detection Rate at University Hospital Bristol

Aim

Diverticulitis is a common cause for acute surgical admissions. UK guidance recommends uncomplicated diverticulitis is managed with antibiotics, and follow-up outpatient lower gastrointestinal (LGI) endoscopy (flexible sigmoidoscopy or colonoscopy) arranged 6-8 weeks after discharge. This audit aimed to assess compliance to national guidance and assess adenoma detection rate.

Method

Retrospective analysis of discharge summaries coded ‘diverticulitis’ from January 2017 – April 2020 at University Hospital Bristol(UHB).

Results

426 patients presented with uncomplicated diverticulitis, mean age 60.5 years (22-92 years). 42% (179/426) of patients underwent LGI endoscopy as an inpatient or on discharge. Median time to outpatient endoscopy was 70 days (6-287 days). 23% (99/426) had LGI endoscopy within the 8-week target. Histology showed: 21% (37/179) polyp; 5% (9/179) tubular adenoma; and one patient had high grade dysplasia. The histology for the remaining 28 patients with polyps showed: hyperplasia; granulation tissue; inflammation; or samples were not sent for histology. No cases of malignancy were detected.

Conclusions

58% of patients admitted with acute uncomplicated diverticulitis did not have a follow-up LGI endoscopy and only 23% had LGI endoscopy within the 8-week target. 21% had a polyp with a 5% rate of tubular adenoma and no cases of malignancy. UHB needs to improve compliance with national guidance for the arrangement of follow-up LGI endoscopy, however the absence of detection of malignancy raises the question of whether we need to re-consider its necessity for patients with uncomplicated diverticulitis.

Colorectal cancer in the young - outcomes following surgical management?

INTRODUCTION

Colorectal cancer (CRC) is the third most common cancer, accounting for approximately 10% of all cancer deaths. The incidence of CRC in young adults and the adolescent population is increasing. This study aims to highlight short-term outcomes for young patients with CRC.

METHODS

Data were collected retrospectively for all patients aged less than 50 years diagnosed with CRC at a university teaching hospital between October 2012 and June 2018. The primary endpoints were disease-free survival (DFS) and overall survival (OS).

RESULTS

A total of 120 patients (65 males, 55 females) with CRC aged under 50 years were initially included; 20 did not receive surgical treatment (12 metastatic adenocarcinoma, 5 metastatic squamous cell cancer (SCC), 3 neuroendocrine tumours (NET)), and 13 patients had insufficient data for analysis and were excluded. A total of 87 patients underwent surgical intervention and 66 with diagnosis of adenocarcinoma were included in survival analysis. Median age of patients was 42 years (19-49 years). Cancer recurrence was seen in 14 patients, 10 showing local, 3 liver and 1 lung metastasis. The median OS was 28 months (3-156 months). The median DFS was 13 months (3-85 months). Overall 5-year survival and DFS were 72% and 59%, respectively. Median survival in the group who did not undergo surgery was 4.5 months (1-15 months).

CONCLUSIONS

CRC is often more advanced and aggressive in younger patients. Current guidelines can result in young patients being investigated/treated for other gastrointestinal conditions before referral for CRC investigation.

Genome assembly of Chiococca alba uncovers key enzymes involved in the biosynthesis of unusual terpenoids

Chiococca alba (L.) Hitchc. (snowberry), a member of the Rubiaceae, has been used as a folk remedy for a range of health issues including inflammation and rheumatism and produces a wealth of specialized metabolites including terpenes, alkaloids, and flavonoids. We generated a 558 Mb draft genome assembly for snowberry which encodes 28,707 high-confidence genes. Comparative analyses with other angiosperm genomes revealed enrichment in snowberry of lineage-specific genes involved in specialized metabolism. Synteny between snowberry and Coffea canephora Pierre ex A. Froehner (coffee) was evident, including the chromosomal region encoding caffeine biosynthesis in coffee, albeit syntelogs of N-methyltransferase were absent in snowberry. A total of 27 putative terpene synthase genes were identified, including 10 that encode diterpene synthases. Functional validation of a subset of putative terpene synthases revealed that combinations of diterpene synthases yielded access to products of both general and specialized metabolism. Specifically, we identified plausible intermediates in the biosynthesis of merilactone and ribenone, structurally unique antimicrobial diterpene natural products. Access to the C. alba genome will enable additional characterization of biosynthetic pathways responsible for health-promoting compounds in this medicinal species.

Genome-wide Inference of Somatic Translocation Events During Potato Dihaploid Production

Potato ( L.) breeders often use dihaploids, which are 2× progeny derived from 4× autotetraploid parents. Dihaploids can be used in diploid crosses to introduce new genetic material into breeding germplasm that can be integrated into tetraploid breeding through the use of unreduced gametes in 4× by 2× crosses. Dihaploid potatoes are usually produced via pollination by haploid inducer lines known as in vitro pollinators (IVP). In vitro pollinator chromosomes are selectively degraded from initially full hybrid embryos, resulting in 2× seed. During this process, somatic translocation of IVP DNA may occur. In this study, a genome-wide approach was used to identify such events and other chromosome-scale abnormalities in a population of 95 dihaploids derived from a cross between potato cultivar Superior and the haploid inducing line IVP101. Most Superior dihaploids showed translocation rates of <1% at 16,947,718 assayable sites, yet two dihaploids showed translocation rates of 1.86 and 1.60%. Allelic ratios at translocation sites suggested that most translocations occurred in individual cell lineages and were thus not present in all cells of the adult plants. Translocations were enriched in sites associated with high gene expression and H3K4 dimethylation and H4K5 acetylation, suggesting that they tend to occur in regions of open chromatin. The translocations likely result as a consequence of double-stranded break repair in the dihaploid genomes via homologous recombination during which IVP chromosomes are used as templates. Additionally, primary trisomy was observed in eight individuals. As the trisomic chromosomes were derived from Superior, meiotic nondisjunction may be common in potato.

Gene Discovery in Gelsemium Highlights Conserved Gene Clusters in Monoterpene Indole Alkaloid Biosynthesis

Genome mining is a routine technique in microbes for discovering biosynthetic pathways. In plants, however, genomic information is not commonly used to identify novel biosynthesis genes. Here, we present the genome of the medicinal plant and oxindole monoterpene indole alkaloid (MIA) producer Gelsemium sempervirens (Gelsemiaceae). A gene cluster from Catharanthus roseus, which is utilized at least six enzymatic steps downstream from the last common intermediate shared between the two plant alkaloid types, is found in G. sempervirens, although the corresponding enzymes act on entirely different substrates. This study provides insights into the common genomic context of MIA pathways and is an important milestone in the further elucidation of the Gelsemium oxindole alkaloid pathway.

Phylogenomic Mining of the Mints Reveals Multiple Mechanisms Contributing to the Evolution of Chemical Diversity in Lamiaceae

The evolution of chemical complexity has been a major driver of plant diversification, with novel compounds serving as key innovations. The species-rich mint family (Lamiaceae) produces an enormous variety of compounds that act as attractants and defense molecules in nature and are used widely by humans as flavor additives, fragrances, and anti-herbivory agents. To elucidate the mechanisms by which such diversity evolved, we combined leaf transcriptome data from 48 Lamiaceae species and four outgroups with a robust phylogeny and chemical analyses of three terpenoid classes (monoterpenes, sesquiterpenes, and iridoids) that share and compete for precursors. Our integrated chemical-genomic-phylogenetic approach revealed that: (1) gene family expansion rather than increased enzyme promiscuity of terpene synthases is correlated with mono- and sesquiterpene diversity; (2) differential expression of core genes within the iridoid biosynthetic pathway is associated with iridoid presence/absence; (3) generally, production of iridoids and canonical monoterpenes appears to be inversely correlated; and (4) iridoid biosynthesis is significantly associated with expression of geraniol synthase, which diverts metabolic flux away from canonical monoterpenes, suggesting that competition for common precursors can be a central control point in specialized metabolism. These results suggest that multiple mechanisms contributed to the evolution of chemodiversity in this economically important family.

Genome sequence of M6, a diploid inbred clone of the high-glycoalkaloid-producing tuber-bearing potato species Solanum chacoense, reveals residual heterozygosity

Cultivated potato (Solanum tuberosum L.) is a highly heterozygous autotetraploid that presents challenges in genome analyses and breeding. Wild potato species serve as a resource for the introgression of important agronomic traits into cultivated potato. One key species is Solanum chacoense and the diploid, inbred clone M6, which is self-compatible and has desirable tuber market quality and disease resistance traits. Sequencing and assembly of the genome of the M6 clone of S. chacoense generated an assembly of 825 767 562 bp in 8260 scaffolds with an N50 scaffold size of 713 602 bp. Pseudomolecule construction anchored 508 Mb of the genome assembly into 12 chromosomes. Genome annotation yielded 49 124 high-confidence gene models representing 37 740 genes. Comparative analyses of the M6 genome with six other Solanaceae species revealed a core set of 158 367 Solanaceae genes and 1897 genes unique to three potato species. Analysis of single nucleotide polymorphisms across the M6 genome revealed enhanced residual heterozygosity on chromosomes 4, 8 and 9 relative to the other chromosomes. Access to the M6 genome provides a resource for identification of key genes for important agronomic traits and aids in genome-enabled development of inbred diploid potatoes with the potential to accelerate potato breeding.

Genome sequence of M6, a diploid inbred clone of the high-glycoalkaloid-producing tuber-bearing potato species Solanum chacoense, reveals residual heterozygosity

Cultivated potato (Solanum tuberosum L.) is a highly heterozygous autotetraploid that presents challenges in genome analyses and breeding. Wild potato species serve as a resource for the introgression of important agronomic traits into cultivated potato. One key species is Solanum chacoense and the diploid, inbred clone M6, which is self-compatible and has desirable tuber market quality and disease resistance traits. Sequencing and assembly of the genome of the M6 clone of S. chacoense generated an assembly of 825 767 562 bp in 8260 scaffolds with an N50 scaffold size of 713 602 bp. Pseudomolecule construction anchored 508 Mb of the genome assembly into 12 chromosomes. Genome annotation yielded 49 124 high-confidence gene models representing 37 740 genes. Comparative analyses of the M6 genome with six other Solanaceae species revealed a core set of 158 367 Solanaceae genes and 1897 genes unique to three potato species. Analysis of single nucleotide polymorphisms across the M6 genome revealed enhanced residual heterozygosity on chromosomes 4, 8 and 9 relative to the other chromosomes. Access to the M6 genome provides a resource for identification of key genes for important agronomic traits and aids in genome-enabled development of inbred diploid potatoes with the potential to accelerate potato breeding.

Extensive genome heterogeneity leads to preferential allele expression and copy number-dependent expression in cultivated potato

Relative to homozygous diploids, the presence of multiple homologs or homeologs in polyploids affords greater tolerance to mutations that can impact genome evolution. In this study, we describe sequence and structural variation in the genomes of six accessions of cultivated potato (Solanum tuberosum L.), a vegetatively propagated autotetraploid and their impact on the transcriptome. Sequence diversity was high with a mean single nucleotide polymorphisms (SNP) rate of approximately 1 per 50 bases suggestive of high levels of allelic diversity. Additive gene expression was observed in leaves (3605 genes) and tubers (6156 genes) that contrasted the preferential allele expression of between 2180 and 3502 and 3367 and 5270 genes in the leaf and tuber transcriptome, respectively. Preferential allele expression was significantly associated with evolutionarily conserved genes suggesting selection of specific alleles of genes responsible for biological processes common to angiosperms during the breeding selection process. Copy number variation was rampant with between 16 098 and 18 921 genes in each cultivar exhibiting duplication or deletion. Copy number variable genes tended to be evolutionarily recent, lowly expressed, and enriched in genes that show increased expression in response to biotic and abiotic stress treatments suggestive of a role in adaptation. Gene copy number impacts on gene expression were detected with 528 genes having correlations between copy number and gene expression. Collectively, these data suggest that in addition to allelic variation of coding sequence, the heterogenous nature of the tetraploid potato genome contributes to a highly dynamic transcriptome impacted by allele preferential and copy number-dependent expression effects.

Meiotic crossovers are associated with open chromatin and enriched with Stowaway transposons in potato

Background

Meiotic recombination is the foundation for genetic variation in natural and artificial populations of eukaryotes. Although genetic maps have been developed for numerous plant species since the late 1980s, few of these maps have provided the necessary resolution needed to investigate the genomic and epigenomic features underlying meiotic crossovers.

Results

Using a whole genome sequencing-based approach, we developed two high-density reference-based haplotype maps using diploid potato clones as parents. The vast majority (81%) of meiotic crossovers were mapped to less than 5 kb. The fine-scale accuracy of crossover detection was validated by Sanger sequencing for a subset of ten crossover events. We demonstrate that crossovers reside in genomic regions of “open chromatin”, which were identified based on hypersensitivity to DNase I digestion and association with H3K4me3-modified nucleosomes. The genomic regions spanning crossovers were significantly enriched with the Stowaway family of miniature inverted-repeat transposable elements (MITEs). The occupancy of Stowaway elements in gene promoters is concomitant with an increase in recombination rate. A generalized linear model identified the presence of Stowaway elements as the third most important genomic or chromatin feature behind genes and open chromatin for predicting crossover formation over 10-kb windows.

Conclusions

Collectively, our results suggest that meiotic crossovers in potato are largely determined by the local chromatin status, marked by accessible chromatin, H3K4me3-modified nucleosomes, and the presence of Stowaway transposons.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-017-1326-8) contains supplementary material, which is available to authorized users.

Genome Reduction Uncovers a Large Dispensable Genome and Adaptive Role for Copy Number Variation in Asexually Propagated Solanum tuberosum

Clonally reproducing plants have the potential to bear a significantly greater mutational load than sexually reproducing species. To investigate this possibility, we examined the breadth of genome-wide structural variation in a panel of monoploid/doubled monoploid clones generated from native populations of diploid potato (Solanum tuberosum), a highly heterozygous asexually propagated plant. As rare instances of purely homozygous clones, they provided an ideal set for determining the degree of structural variation tolerated by this species and deriving its minimal gene complement. Extensive copy number variation (CNV) was uncovered, impacting 219.8 Mb (30.2%) of the potato genome with nearly 30% of genes subject to at least partial duplication or deletion, revealing the highly heterogeneous nature of the potato genome. Dispensable genes (>7000) were associated with limited transcription and/or a recent evolutionary history, with lower deletion frequency observed in genes conserved across angiosperms. Association of CNV with plant adaptation was highlighted by enrichment in gene clusters encoding functions for environmental stress response, with gene duplication playing a part in species-specific expansions of stress-related gene families. This study revealed unique impacts of CNV in a species with asexual reproductive habits and how CNV may drive adaption through evolution of key stress pathways.

A G-Box-Like Motif Is Necessary for Transcriptional Regulation by Circadian Pseudo-Response Regulators in Arabidopsis

PSEUDO-RESPONSE REGULATORs (PRRs) play overlapping and distinct roles in maintaining circadian rhythms and regulating diverse biological processes, including the photoperiodic control of flowering, growth, and abiotic stress responses. PRRs act as transcriptional repressors and associate with chromatin via their conserved C-terminal CCT (CONSTANS, CONSTANS-like, and TIMING OF CAB EXPRESSION 1 [TOC1/PRR1]) domains by a still-poorly understood mechanism. Here, we identified genome-wide targets of PRR9 using chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) and compared them with PRR7, PRR5, and TOC1/PRR1 ChIP-seq data. We found that PRR binding sites are located within genomic regions of low nucleosome occupancy and high DNase I hypersensitivity. Moreover, conserved noncoding regions among Brassicaceae species are enriched around PRR binding sites, indicating that PRRs associate with functionally relevant cis-regulatory regions. The PRRs shared a significant number of binding regions, and our results indicate that they coordinately restrict the expression of target genes to around dawn. A G-box-like motif was overrepresented at PRR binding regions, and we showed that this motif is necessary for mediating transcriptional regulation of CIRCADIAN CLOCK ASSOCIATED 1 and PRR9 by the PRRs. Our results further our understanding of how PRRs target specific promoters and provide an extensive resource for studying circadian regulatory networks in plants.

Transcriptional coordination of physiological responses in Nannochloropsis oceanica CCMP1779 under light/dark cycles

Nannochloropsis oceanica CCMP1779 is a marine unicellular stramenopile and an emerging reference species for basic research on oleogenic microalgae with biotechnological relevance. We investigated its physiology and transcriptome under light/dark cycles. We observed oscillations in lipid content and a predominance of cell division in the first half of the dark phase. Globally, more than 60% of the genes cycled in N. oceanica CCMP1779, with gene expression peaking at different times of the day. Interestingly, the phase of expression of genes involved in certain biological processes was conserved across photosynthetic lineages. Furthermore, in agreement with our physiological studies we found the processes of lipid metabolism and cell division enriched in cycling genes. For example, there was tight coordination of genes involved in the lower part of glycolysis, fatty acid synthesis and lipid production at dawn preceding lipid accumulation during the day. Our results suggest that diel lipid storage plays a key role for N. oceanica CCMP1779 growth under natural conditions making this alga a promising model to gain a basic mechanistic understanding of triacylglycerol production in photosynthetic cells. Our data will help the formulation of new hypotheses on the role of cyclic gene expression in cell growth and metabolism in Nannochloropsis.

Light and the circadian clock mediate time-specific changes in sensitivity to UV-B stress under light/dark cycles

In Arabidopsis, the circadian clock regulates UV-B-mediated changes in gene expression. Here it is shown that circadian clock components are able to inhibit UV-B-induced gene expression in a gene-by-gene-specific manner and act downstream of the initial UV-B sensing by COP1 (CONSTITUTIVE PHOTOMORPHOGENIC 1) and UVR8 (UV RESISTANCE LOCUS 8). For example, the UV-B induction of ELIP1 (EARLY LIGHT INDUCIBLE PROTEIN 1) and PRR9 (PSEUDO-RESPONSE REGULATOR 9) is directly regulated by LUX (LUX ARRYTHMO), ELF4 (EARLY FLOWERING 4), and ELF3. Moreover, time-dependent changes in plant sensitivity to UV-B damage were observed. Wild-type Arabidopsis plants, but not circadian clock mutants, were more sensitive to UV-B treatment during the night periods than during the light periods under diel cycles. Experiments performed under short cycles of 6h light and 6h darkness showed that the increased stress sensitivity of plants to UV-B in the dark only occurred during the subjective night and not during the subjective day in wild-type seedlings. In contrast, the stress sensitivity of Arabidopsis mutants with a compromised circadian clock was still influenced by the light condition during the subjective day. Taken together, the results show that the clock and light modulate plant sensitivity to UV-B stress at different times of the day.

Direct regulation of abiotic responses by the Arabidopsis circadian clock component PRR7

Up to 30% of the plant transcriptome is circadian clock-regulated in different species; however, we still lack a good understanding of the mechanisms involved in these genome-wide oscillations in gene expression. Here, we show that PSEUDO-RESPONSE REGULATOR 7 (PRR7), a central component of the Arabidopsis clock, is directly involved in the repression of master regulators of plant growth, light signaling and stress responses. The expression levels of most PRR7 target genes peak around dawn, in an antiphasic manner to PRR7 protein levels, and were repressed by PRR7. These findings indicate that PRR7 is important for cyclic gene expression by repressing the transcription of morning-expressed genes. In particular we found an enrichment of the genes involved in abiotic stress responses, and in accordance we observed that PRR7 is involved in the oxidative stress response and the regulation of stomata conductance.

Takayasu's Arteritis: an important cause of stroke in younger patients

Stroke in young patients is important and early diagnosis of Takayasu's Arteritis as the cause will assist in acute management. A retrospective notes review of six patients presenting with acute neurological symptoms secondary to TA was performed. Three male and three female patients (mean age of 32.2 years) were identified. Neurological presentations included four ischaemic strokes, one TIA, and one syncopal episode. Pulse loss, bruit, or a difference in brachial blood pressures was evident in five patients at presentation. 4 patients had a previous history of TIA, 3 had prior ischaemic limb symptoms and 1 had prodromal symptoms. A history of limb ischaemia, prodromal symptoms, absent pulses and asymmetric blood pressure should alert the clinician to possible TA.

Effects of dose and duration of continuous GnRH-agonist treatment on induction of estrus in beagle dogs: competing and concurrent up-regulation and down-regulation of LH release

Dose-response estrus-induction trials were conducted during anestrus in 93 treated and 6 control bitches, a continuous administration of the GnRH-agonist lutrelin with a potency 150 x GnRH, and at six different doses from 0.2 to 4.8 microg/kg/d for 7-14 days in 15 groups of six to eight dogs each in defined stages of natural or pharmacologically determined anestrus. Agonist treatment induced clinically and cytologically normal proestrus (in 89% of cases) within 4.8 +/- 0.2 x days, and resulted in behavioral estrus (71%), spontaneous late-proestrus LH (and FSH) surges, ovulation (59%) and pregnancy (44%) in a dose dependent manner. Outcomes of ovulation and pregnancy in most cases required that the dose be sufficiently large enough to routinely stimulate a large initial increase in LH and FSH (i.e., > or = 0.6 microg/kg/d), and of sufficient duration (i.e., > 7 days) to ensure that supra-basal gonadotropin levels persistedntil no longer needed for spontaneous continuation of an induced proestrus. Success additionally required that the GnRH dose be modest enough (i.e., < 1.8 microg/kg/d) to not excessively down-regulate spontaneous pre-ovulatory surge release of gonadotropin or be removed shortly before or at the time when the LH surges typically occurred (10-13 days after initiation of treatment). The 1.8 microg dose was compared to saline to assess the time course of its down-regulation action on serum LH in six ovariohysterectomized bitches compared to four saline-related controls. Results in intact bitches receiving the 1.8-microg doses demonstrated an LH-releasing effect for 10-11 days that overlapped a period of obvious down-regulation seen with the same dose after 3 days in the ovariohysterectomized bitches. In the latter, however, complete down-regulation to anestrus-like values did not occur until after 18-21 days of treatment. A dose of 0.6 microg/kg/d for 12 days yielded the best estrus-induction results, including pregnancy rates of 100% in six bitches treated in natural-anestrus bitches, six bitches in which anestrus had been advanced by a luteolytic prostaglandin treatment and in six bitches in which anestrus had been extended by progesterone implants administered for 3 months. Although lutrelin is not commercially available, these results provide guidelines for the development of estrus-inducing protocols with other GnRH-agonists of known biopotencies.

Spontaneous frequency of exon skipping in the human HPRT gene

In order to elucidate the mechanisms of mRNA splicing fidelity and the mutagenic potential of aberrant mis-spliced transcripts we have investigated the frequency of spontaneous exon skipping in the human hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene in well characterized human primary fibroblasts isolated from two different individuals. In these cells, coexisting with the WT species, we also detected three aberrant HPRT transcripts missing exon IV, VII, or VIII. We were unable to detect transcripts missing exon II, III, V, or VI. Significantly, all the exons affected by skipping do not generate new stop codons more than 50 nucleotides upstream from the 3' most exon-exon junction. Exon VIII was the most prone to skipping with a relative frequency to WT of 0.019+/-0.004 (approximately one aberrant transcript per 50 WT transcripts). Exon IV exhibited a relative frequency of skipping of 0.006+/-0.002 ((approximately one aberrant transcript per 150 WT transcripts) and exon VII exhibited a relative frequency of skipping of 0.003+/-0.002 ((approximately one aberrant transcript per 300 WT transcripts). These data demonstrate that aberrant transcripts with exon skipped are generated spontaneously in humans and some appear to persist in the cell.

Moving out and moving on: some ethnographic observations of deinstitutionalization in an Australian community

Since the 1950s deinstitutionalization has taken place for people with mental illnesses in the Western world. The growth of community care and residential facilities, as well as planning and implementation of policies, has varied in timing and orientation. An appreciation of the process of change affecting people discharged to the community highlights their strength, resilience, and vulnerabilities. This paper outlines a two and a half year ethnographic qualitative study undertaken in Australia, where 47 long-stay psychiatric inpatients were discharged to the community. The process accompanied the amalgamation of two major psychiatric hospitals, resulting in the closure of one. Findings demonstrated slow but positive change for residents as they reintegrated into the community. A separate quantitative and economic study was undertaken alongside the qualitative study (for results see Hobbs, et al., 2000; Newton, et al, 2000; Lapsley, et al., 2000).

Deinstitutionalisation for long-term mental illness: an ethnographic study

OBJECTIVE

Deinstitutionalisation of seriously mentally ill people in the developed world, including Australia, has occurred since the middle of this century. Evaluation of the effects of this change on the lives of individuals is of paramount importance to ensure that policies are acceptable and effective. Increasingly, multifaceted studies are considered essential for comprehensive health research. The qualitative aspect of this study complements the clinical and economic components.

METHOD

An ethnographic approach enabled contextual, qualitative data to be gathered from within the social world of 47 hospital residents as they moved to the community. A social anthropologist acting explicitly as a participant observer undertook fieldwork over two and a half years both pre- and post-discharge. Qualitative data were collected, stored and analysed separately from quantitative and economic data.

RESULTS

Ethnographic findings generally supported and, in many cases, mirrored clinical results. Of the total cohort of 47 patients transferred to the community, the 40 who continue to live outside of hospital all reported a preference for community living. The importance of freedom and simple liberties cannot be underestimated as factors that enabled this resilient group of people to work creatively through difficult periods.

CONCLUSION

Properly planned and resourced deinstitutionalisation not only maintains people with a prolonged mental illness outside of hospital, it also enhances their quality of life. Subjective descriptive material focusing on personal experiences adds meaning to quantitative research data allowing health professionals to more fully understand the implications of health policy on the lives of individuals.

Deinstitutionalisation for long-term mental illness: cost differences in hospital and community care

OBJECTIVE

This project studied the cost analysis of psychiatric hospital and then community care for long-stay patients with chronic mental illness discharged during the closure of a psychiatric hospital in Sydney.

METHOD

Expenditure and income data in both settings were collected. Costs were analysed on an occupied bed-day basis.

RESULTS

The hospital setting cost more per patient per day compared with the various community costs which were one-third to one-half of the comparable hospital costs.

CONCLUSIONS

The analysis demonstrated overall that hospital care was nearly twice as expensive as care in the community setting. The factors which may have influenced, although not necessarily altered, the substance of the findings largely related to 'organisational efficiency'. The mental hospital as an older, more rigid system was likely to be less efficient than the newer community service provision which was under intensive scrutiny both clinically and financially by all interested parties.

Deinstitutionalisation for long-term mental illness: a 2-year clinical evaluation

OBJECTIVE

The closure of a long-stay psychiatric hospital in Sydney caused the transfer of an initial 40 very long-term patients to four community residences, each with 10 beds, for a continuing process of deinstitutionalisation. Community psychiatric service support and 24-h supervision were provided. This paper describes the residents' clinical progress which was assessed over a 2-year period.

METHOD

This study employed a quasi-experimental longitudinal design. Evaluation commenced prior to discharge and continued for 2 years following community relocation using the Brief Psychiatric Rating Scale, Life Skills Profile, Social Behaviour Scale, Montgomery Asberg Depression Rating Scale and Quality Of Life measures. Readmission, demographic, case history and medication data were also collected.

RESULTS

Of the 40 patients initially transferred to the community, seven required long-term readmission to hospital (either prior to or after amalgamation) and one patient died of medical causes. Additional patients transferred from the hospital to the community following the readmissions. Three of these additional patients had achieved a 2-year community tenure during the study period and were included in the clinical evaluation. The 35 residents in total who remained in the community for 2 years, demonstrated a significant improvement in psychotic symptoms, without significant change in the level of neuroleptic medication. Importantly, the 2 years of community living resulted in a significant increase in the residents' life satisfaction. There were no statistically significant changes in residents' living skills, depressive symptoms or social behaviour problems over the 2 years, indicative of the need for supervision and community service support following deinstitutionalisation. Over the 2-year period, some 37% of the residents required temporary readmission.

CONCLUSION

This study demonstrates the clinical effectiveness of deinstitutionalisation, when planned within a mental health system with adequate community resources.

Potential impact of antiarrhythmic drugs versus implantable defibrillators on the management of ventricular arrhythmias: the Midlands trial of empirical amiodarone versus electrophysiologically guided intervention and cardioverter implant registry data

BACKGROUND

Survival was prolonged in selected patients with sustained ventricular arrhythmias who received implantable cardioverter defibrillators (ICDs) in the antiarrhythmics versus implantable defibrillators (AVID) study. The Midlands trial of empirical amiodarone versus electrophysiologically guided intervention and cardioverter implant in ventricular arrhythmias (MAVERIC) registry is a population based trial.

OBJECTIVE

To determine the number of patients who satisfy the AVID criteria because of the high cost of ICDs.

DESIGN

Observational study, based on a continuing trial.

SETTING

All coronary care units in the Midlands region in the United Kingdom (population 9.1 million).

PATIENTS

Patients presenting to a coronary care unit with sustained ventricular arrhythmias not related to an acute myocardial infarction are entered onto the registry. Those who consent to the MAVERIC study are randomised to receive either empirical amiodarone or electrophysiologically guided treatment. Demographic data, details of clinical presentation, and echocardiographic findings are collected. These data have been used to calculate the number of patients who satisfy the AVID criteria and would benefit from ICD implantation. The financial implications have been calculated for the region and nationally.

RESULTS

132 patients were entered onto the registry during the first five months of the MAVERIC study; 69 patients fulfilled the AVID criteria. Extrapolation of these data over a 12 month period suggests implantation of at least 166 new ICDs (compared with 23 implants in 1996). This would increase the UK ICD implant rate from five to at least 18 per million of the population, costing the National Health Service 24.1 Pounds million per annum.

CONCLUSION

Application of the AVID criteria in the UK will cause a great increase in the ICD implant rate, with serious financial implications.

Incidence of spontaneous ovulation in young, group-housed cats based on serum and faecal concentrations of progesterone

Cats are considered to be reflex ovulators that exhibit a luteal phase (pregnancy or pseudopregnancy) only after copulatory stimulation. In a group-housed colony of 15 1-year-old domestic queens, 23 noncopulatory, spontaneous ovulations were observed in 87% of the queens over 4.5 months based upon the detection of increased concentrations of progesterone in faeces, serum, or both. Luteal phases were detectable for periods of 3 to 5 weeks with peak progesterone concentrations averaging 21 +/- 1 ng ml-1 in serum and 1874 +/- 281 ng g-1 in faeces. Individual cats exhibited from 0 to 3 spontaneous ovulations and subsequent pseudopregnancies each. A male was added to a separate cage within the room during the last 1.5 months of the study. The incidence of ovulation per 10 day period ranged from 0% to 22% before introduction of the male and from 33% to 57% immediately after introduction of the male, suggesting a potential noncopulatory influence of the male on the incidence of spontaneous ovulation in young, group-housed cats.

Postimplantation increase in plasma fibrinogen concentration with increase in relaxin concentration in pregnant dogs

OBJECTIVE

To determine time courses of pregnancy-related changes in plasma fibrinogen, serum relaxin, and serum C-reactive protein-like immunoreactivity (CRP-LI) concentrations in pregnant and nonpregnant dogs.

ANIMALS

16 pregnant and 13 nonpregnant Beagles, 6 pregnant Beagles, and 3 pregnant and 3 nonpregnant dogs of other breeds.

PROCEDURE

Fibrinogen was measured by nephelometric centrifugal analysis of light scatter in plasma samples of all dogs, and CRP-LI was measured by fluorescence immunoassay in selected sera from 10 pregnant and 10 nonpregnant dogs. Relaxin was measured in selected sera from 7 pregnant and 7 nonpregnant dogs.

RESULTS

During pregnancy, fibrinogen concentration increased between days 21 and 30 after the luteinizing hormone surge, and was > 280 mg/dl between days 29 and 50 in 84 of 86 samples, with peak values 539 +/- 29 mg/ dl higher (P < 0.01) than those in nonpregnant dogs (188 +/- 8 mg/dl), higher values from days 21 to 50 (P < 0.01) than those in nonpregnant dogs, and values similar to those in nonpregnant dogs after day 50. Relaxin concentration was increased from days 26 to 30 and 0 to 4 days after fibrinogen concentration increased in pregnant dogs, and was not detectable in nonpregnant dogs. The CRP-LI concentration was higher in pregnant dogs at days 26 to 50, but values were inconsistent within and among dogs, and near the limit of sensitivity of the assay.

CONCLUSIONS

Concentration of the acute-phase reactant protein fibrinogen increases after day 20 following implantation in dogs, at or just before the pregnancy-specific increase in relaxin concentration from days 26 to 30, and persists until day 50.

CLINICAL RELEVANCE

Fibrinogen assay may be useful for pregnancy diagnosis in dogs.

Effect of hydrocortisone and disodium cromoglycate on mast cell-mediator release induced by substance P

Release of inflammatory mediators from mast cells following immunoglobulin bridging by specific allergens triggers episodes of asthma and bronchial hyperreactivity. Recent evidence has shown that neuropeptides, such as substance P (SP), may modulate the pulmonary inflammatory response in these airway diseases. This suggests that SP may affect secretory events of mast cells. To investigate these effects, resident peritoneal mast cells were collected from Sprague-Dawley male rats and stimulated with Con A (utilizes surface-bound immunoglobulin), compound 48/80 (acts in a peptide-like manner) and SP. Secretion was assessed as the release of preloaded [14C]serotonin. All secretagogues induced dose-dependent release. Pharmacologic modulation of release was then studied with two drugs employed for treatment of airway disease, hydrocortisone, a classical anti-inflammatory steroid, and disodium cromoglycate (DSCG). Following pretreatment with 5 mumol/l hydrocortisone, serotonin release induced by Con A was inhibited by 59%. No inhibition was noted with compound 48/80 or SP release. Similarly, following DSCG (300 mumol/l) pretreatment, 40% inhibition of release was noted with Con A, but no inhibition occurred following compound 48/80- or SP-stimulated release. Collectively, these results suggest that mast cells possess multiple activation-secretion coupling pathways which respond differently to clinically used pharmacologic agents. Diseases involving SP modulation of mast cell mediator release may not be successfully treated with anti-inflammatory steroids or DSCG.

Determination of blood flow to the transplanted kidney. A novel application of phase-contrast, cine magnetic resonance imaging

There is at present no noninvasive method that reliably measures blood flow in the poorly functioning renal allograft. The present study was designed to evaluate phase-contrast cine magnetic resonance imaging (PC-cine-MRI) for this purpose. We recruited for study 18 patients who had received kidney transplants 13-66 months earlier from closely related living donors. As judged by the glomerular filtration rate, which was elevated for a single kidney (76 +/- 4 ml/min 1.73 m2), allograft function was excellent, permitting the assumption of unimpaired renal extraction of paminohippuric acid (PAH). Allograft blood flow was determined consecutively on the same day, first by the standard PAH clearance technique and they by the product of the velocity of protons and renal vein cross-sectional area using PC-cine-MRI. MRI determinations could not be completed because of claustrophobia in two patients and failure to image the terminus of the allograft vein another two. Comparison of blood flow in the remaining 14 subjects revealed the two techniques to be strongly related (r = 0.91, P < 0.001). On the average, the renal blood flow rate was similar by each method; 732 +/- 62 by PAH clearance and 703 +/- 69 ml/min by PC-cine-MRI, but the agreement among individuals between the two methods was only modest, with a 95% confidence interval of agreement from -214 to +254 ml/min. We conclude that PC-cine-MRI provides a fairly accurate and noninvasive method for determining the rate of blood flow in the transplanted kidney. With further refinement it should permit the role of depressed blood flow in a variety of acute and chronic forms of human allograft dysfunction to be elucidated in humans for the first time.

Management of Kawasaki disease in the British Isles

Kawasaki disease in the British Isles was surveyed by an active reporting scheme, based on all cases reported to the British Paediatric Surveillance Unit that were diagnosed between 1 January and 31 December 1990. The study was prompted by the need to investigate the high case fatality rate of Kawasaki disease of 2% observed in 1988. One hundred and sixty three patients were identified of whom six (3.7%) died. Forty five children (28%) suffered cardiac complications of which 39 (24%) were coronary artery abnormalities; five children were diagnosed at postmortem examination, and coronary artery abnormalities were detected by echocardiography in 34. One hundred and forty nine children (93%) had echocardiography. High thrombocytosis, leucocytosis, duration of fever, and younger age were associated with the presence of coronary artery abnormalities. Erythrocyte sedimentation rate, sex, and the number of diagnostic criteria were not. One hundred and thirty three children (87%) received aspirin. Ninety three children (61%) received intravenous gammaglobulin (IVGG). Children were more likely to receive IVGG if they had thrombocytosis or typical Kawasaki disease. The incidence of coronary artery abnormalities was found to be similar in those treated with IVGG (29%) and those untreated (20%), including those treated within 10 days of onset. This may have reflected selection of the more serious cases to receive IVGG or that Kawasaki disease in the British Isles is a different illness to that experienced elsewhere. It amy be, however, that IVGG is less effective in the treatment of British patients with Kawasaki disease than has been the experience in the United States and Japan. These observations emphasise the need for a therapeutic trial of treatment modalities for Kawasaki disease in the UK and the Republic of Ireland.

Listeriosis surveillance: 1992

The annual reported totals of cases of listeriosis in England, Wales and Northern Ireland have remained low over the last three years and a total of 108 cases was reported in 1992. The clinical and epidemiological features reported in 1992 were similar to those in previous years and in other countries, except for a shift in the seasonal peak to the summer (a pattern consistently seen before the upsurge in 1987) and a reduction in the case fatality rate of non pregnancy-associated cases.

Reye's syndrome in the British Isles: report for 1990/91 and the first decade of surveillance

The Reye's syndrome (RS) surveillance scheme for the British Isles, jointly organised by the British Paediatric Association and the PHLS Communicable Disease Surveillance Centre, was established in 1981. In the ten years that have followed, there has been a gradual decline in the number, and the age, of cases reported. However, the proportion of cases whose diagnosis was subsequently revised to that of an inherited metabolic disorder, has increased. These trends have been influenced by the change from 'passive' to 'active' case ascertainment in 1986; the aspirin warning issued by the Committee on Safety of Medicines in June 1986; the 1989 influenza epidemic; and the increasing awareness of conditions that mimic RS, particularly inherited metabolic disorders involving defects of fatty acid oxidation. The cases reported in 1990/91 showed the lowest annual incidence recorded so far and a median age of less than ten months (compared with 15 months in the first six years of surveillance). There was a reduction in the case fatality rate in 1990/91 (although still high at 38%) but it is of concern that two children had had pre-admission exposure to aspirin. Parents should be kept aware of the dangers of giving aspirin preparations to children with feverish illnesses.

Listeriosis surveillance: 1991

A total of 130 cases of listeriosis was reported in England, Wales and Northern Ireland in 1991. This represents a slight increase on the 1990 total of 118 reports but a marked decline compared with the peak incidence of reporting of 291 in 1988, which was part of an upsurge of cases between 1987 and mid 1989. Two epidemiological features of note in 1991 were the reappearance of a late summer-autumn peak in cases (commonly seen prior to 1987) and an increase in the number of reports among younger patients and children. The decline in listeriosis observed during the second half of 1989, which followed government health warnings about the consumption of pâté, and the continued low level of reporting since 1989 may be due to the disappearance of a common food source. However, in the light of the recent outbreak of listeriosis in France it is important that diagnostic vigilance and warnings about high risk foods are maintained.

Short-term responsiveness of membranous glomerulopathy to cyclosporine

We administered a 12-week course of cyclosporine (CsA) (4 to 6 mg/kg/24 h) to nephrotic patients with membranous glomerulopathy (MG). Nephrotic patients with minimal change nephropathy (MCN) served as a comparison group. We evaluated the effects of CsA on proteinuria, glomerular function, and the release of cytokines by peripheral blood mononuclear cells in culture. Proteinuria was restored to normal levels within 2 to 4 weeks in MCN. Proteinuria declined from nephrotic to subnephrotic levels (< 3,500 mg/24 h) in 10 of 14 patients with MG, also within 2 to 4 weeks of onset of therapy. The four nonresponders exhibited a rapidly progressive and presumably irreversible form of MG culminating in renal failure. On average, fractional clearances of albumin and IgG declined by 59% and 73% in MG (P < 0.005); corresponding declines in MCN were by 99% (P < .0001). Corresponding rates of glomerular filtration in each glomerular injury remained unchanged. A strong trend for proteinuria to relapse after CsA was withdrawn was evident in both disorders. The release of tumor necrosis factor (TNF)-alpha by mononuclear cells in culture was enhanced in each glomerular injury, both before and after the course of CsA. We conclude that the proteinuria in most cases of MG exhibits a responsiveness to CsA that is qualitatively similar to, but less complete than, that in MCN. The rapidity with which barrier function improves suggests a possible role for cell-mediated immune injury in MG.

Normal renal blood flow measurement using phase-contrast cine magnetic resonance imaging

RATIONALE AND OBJECTIVES

This study assesses the ability of a cardiac-gated phase-contrast magnetic resonance imaging (MRI) technique to measure renal blood flow (RBF) noninvasively in humans.

METHODS

In nine normal volunteers, total RBF in the renal arteries and in the left renal vein was estimated by MRI and correlated with RBF determined by the clearance of para-aminohippuric acid (CPAH) and the hematocrit level.

RESULTS

Correlation of RBF estimated from left renal vein flow, with RBF by CPAH-hematocrit, yielded r = .86 (P less than .003). Repeated measurement of RBF by MRI demonstrated a high degree of reproducibility, with coefficients of variation ranging from 4.8% to 8.9%. However, the MRI measurements of arterial flow did not significantly correlate with the standard measurements.

CONCLUSIONS

Reproducible noninvasive measurement of normal RBF is possible with the phase-contrast MRI technique used to measure renal venous blood flow.

Listeriosis surveillance: 1990

The annual numbers of reports of listeriosis in England, Wales and Northern Ireland received by the PHLS Communicable Disease Surveillance Centre (CDSC) and the Division of Microbiological Reagents (DMR) have shown remarkable changes in recent years. There was a near doubling in 1987 compared to 1986; a further increase in 1988; a sharp decline in 1989 (which occurred in the second half of that year) and, finally, the total in 1990 was the lowest since 1984. The rise and fall particularly (but not exclusively) involved pregnancy-associated cases and illness caused by serotype 4. The epidemiological and clinical features reported in 1990 were otherwise similar to those reported in previous years and in other countries. Patients with the non pregnancy-associated (also called 'adult/juvenile') type were in the majority, most of whom had an underlying disorder associated with impaired immunity. The reason for the changes in reported incidence is not completely understood but is probably due to the emergence and disappearance of a common food source of the organism. There is, however, no cause for complacency. Diagnostic vigilance must be maintained and vulnerable groups should adhere to existing dietary advice.

Cyclosporine-induced chronic nephropathy: an obliterative microvascular renal injury

Physiologic and morphologic techniques have been used to study kidneys of 200 cardiac transplant recipients treated with either low- or high-dose cyclosporine. After 12 months, both low- (4.6 +/- 0.4) and high-dose cyclosporine (6.3 +/- 0.3 mg/kg/24 h; P less than 0.01) were associated with depression of glomerular filtration rate below values in a third group of 100 recipients never exposed to cyclosporine by 40 to 47%. Determination of renovascular pressures and flows as well as analysis of transglomerular sieving of dextrans revealed renal vascular resistance in cyclosporine-treated recipients to be elevated greater than twofold, due largely to an increase in preglomerular resistance. Morphologic changes in renal tissue of both cyclosporine groups included an occlusive afferent arteriolopathy with downstream collapse or sclerosis of glomeruli. Ischemic nephrons were associated with patchy fibrosis of the surrounding interstitium. Follow-up for up to 9 yr reveals persistent but stable azotemia, on average. Longitudinal physiologic studies over a 48-month period (N = 15) during which cyclosporine was reduced in dosage (to 3.1 +/- 0.3 mg/kg) or withdrawn revealed a persistently reduced but constant level of glomerular filtration rate. Increasing ischemic glomerular collapse and sclerosis were observed at repeat renal biopsy. Remnant (spared) glomeruli exhibited hypertrophy; presumably elevated single nephron glomerular filtration rate maintained two-kidney glomerular filtration rate constant despite the declining fraction of functional glomeruli. By actuarial analysis, the cumulative incidence of end-stage renal failure in cardiac transplant recipients treated at this institution from 1980 onwards with continuous cyclosporine therapy has reached 10%.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide and response to changing plasma volume in diabetic nephropathy

We evaluated the renal and hormonal responses to volume expansion induced by water immersion in subjects with diabetic nephropathy (n = 12) and in healthy control subjects (n = 9). Immersion induced similar average increments in sodium excretion (+/- 223 vs. 176 mumol/min) and comparable decrements in renovascular resistance (RVR; -15 vs. -16 U). However, whereas the control subjects responded uniformly, the response among diabetic subjects was highly variable, with a subset of patients exhibiting paradoxical antinatriuresis and vasoconstriction. Immersion was associated with marked elevation of atrial natriuretic peptide (ANP) in plasma of diabetic versus control subjects (61 +/- 9 vs. 19 +/- 2 pM, respectively; P less than 0.001). Yet for each picomolar increment in plasma ANP during immersion, the corresponding increases in urinary excretion of cyclic guanosine monophosphate (26 vs. 279 pmol/min) and sodium (9 vs. 47 mumol/min) and the reciprocal lowering of RVR (0.7 vs. 1.9 U) were blunted in the diabetic versus control group. Volume contraction in the postimmersion period was associated with disproportionate antinatriuresis and renal vasoconstriction in the diabetic group, despite a persistent elevation of ANP (29 +/- 2 vs. 16 +/- 2 pM, P less than 0.01). We propose that renal insensitivity to ANP in diabetic nephropathy could contribute to altered vasoreactivity and abnormal excretory responsiveness to changing plasma volume. Blunted natriuresis in response to ANP release and enhanced sodium retention during volume contraction could account for the expanded extracellular fluid volume that has consistently been reported to accompany the development of diabetic nephropathy.

Extent of glomerular injury in active and resolving lupus nephritis: a theoretical analysis

Patients with diffuse, proliferative lupus nephritis (DPLN) were subjected to differential solute clearances (n = 22) and serial renal biopsy (n = 11) before and again after 6-12 mo of immunosuppressive therapy. Glomerular sieving of dextrans of graded size was analyzed with a heteroporous membrane model. This revealed active DPLN to be associated with 1) a reduction of overall pore density accompanied by a 53% depression of glomerular filtration rate (GFR), and 2) appearance of a subset of large, nondiscriminatory pores, which accounted for the observed nephrotic level of proteinuria. Morphometric analysis of biopsy tissue provided evidence of reduced filtration surface area due to global or segmental occlusion of capillary loops in glomerular tufts. Activity of DPLN resolved posttreatment. A computed increase in pore density was associated with a 24% increment in GFR; a marked reduction in the fraction of shuntlike pores was accompanied by a parallel reduction of proteinuria into a subnephrotic range. Repeat biopsy revealed diminished glomerular cellularity, fewer immune deposits, and an ensuing increase in the fraction of tuft area occupied by patent loops. Epithelial filtration slit frequency also increased. Neither functional nor structural recovery was complete, however. Residual pore density approximated only 23-35% of that in healthy controls, and corresponding shuntlike pores were threefold more prominent. We conclude that severe DPLN is only partially reversible by current modalities of treatment and that the ensuing residual injury is far more severe than suggested by conventional tests of renal function.