Comprehensive proteomics analysis of polyhydroxyalkanoate (PHA) biology in Pseudomonas putida KT2440: the outer membrane lipoprotein OprL is a newly identified phasin

Pseudomonas putida KT2440 is an important bioplastic-producing industrial microorganism capable of synthesizing the polymeric carbon-rich storage material, polyhydroxyalkanoate (PHA). PHA is sequestered in discrete PHA granules, or carbonosomes, and accumulates under conditions of stress, for example low levels of available nitrogen. The pha locus responsible for PHA metabolism encodes both anabolic and catabolic enzymes, a transcription factor, and carbonosome-localized proteins termed phasins. The functions of phasins are incompletely understood but genetic disruption of their function causes PHA-related phenotypes. To improve our understanding of these proteins, we investigated the PHA pathways of P.putida KT2440 using three types of experiment. First, we profiled cells grown in nitrogen-limited and nitrogen-excess media using global expression proteomics, identifying sets of proteins found to co-ordinately increase or decrease within clustered pathway. Next, we analysed the protein composition of isolated carbonosomes, identifying two new putative components. We carried out physical interaction screens focused on PHA-related proteins, generating a protein-protein network comprising 434 connected proteins. Finally, we confirmed that the outer membrane protein OprL (the Pal component of the Pal-Tol system) localizes to the carbonosome and shows a PHA-related phenotype, and therefore is a novel phasin. The combined datasets represent a valuable overview of the protein components of the PHA system in P.putida highlighting the complex nature of regulatory interactions responsive to nutrient stress.

Transcriptomics and proteomics revealed sex differences in human pulmonary microvascular endothelial cells

Marked sexual dimorphism is displayed in the onset and progression of pulmonary hypertension (PH). Females more commonly develop pulmonary arterial hypertension, yet females with pulmonary arterial hypertension and other types of PH have better survival than males. Pulmonary microvascular endothelial cells play a crucial role in pulmonary vascular remodeling and increased pulmonary vascular resistance in PH. Given this background, we hypothesized that there are sex differences in the pulmonary microvascular endothelium basally and in response to hypoxia that are independent of the sex hormone environment. Human pulmonary microvascular endothelial cells (HPMECs) from healthy male and female donors, cultured under physiological shear stress, were analyzed using RNA sequencing and label-free quantitative proteomics. Gene set enrichment analysis identified a number of sex-different pathways in both normoxia and hypoxia, including pathways that regulate cell proliferation. In vitro, the rate of proliferation in female HPMECs was lower than in male HPMECs, a finding that supports the omics results. Interestingly, thrombospondin-1, an inhibitor of proliferation, was more highly expressed in female cells than in male cells. These results demonstrate, for the first time, important differences between female and male HPMECs that persist in the absence of sex hormone differences and identify novel pathways for further investigation that may contribute to sexual dimorphism in pulmonary hypertensive diseases.NEW & NOTEWORTHY There is marked sexual dimorphism in the development and progression of pulmonary hypertension. We show differences in RNA and protein expression between female and male human pulmonary microvascular endothelial cells grown under conditions of physiological shear stress, which identify sex-different cellular pathways both in normoxia and hypoxia. Importantly, these differences were detected in the absence of sex hormone differences. The pathways identified may provide novel targets for the development of sex-specific therapies.

High-Soluble-Fiber Diet Attenuates Hypoxia-Induced Vascular Remodeling and the Development of Hypoxic Pulmonary Hypertension

BACKGROUND

Hypoxic pulmonary hypertension is a difficult disease to manage that is characterized by sustained elevation of pulmonary vascular resistance and pulmonary artery pressure due to vasoconstriction, perivascular inflammation, and vascular remodeling. Consumption of soluble-fiber is associated with lower systemic blood pressure, but little is known about its ability to affect the pulmonary circulation.

METHODS

Mice were fed either a low- or high-soluble-fiber diet (0% or 16.9% inulin) and then exposed to hypoxia (FiO2, 0.10) for 21 days to induce pulmonary hypertension. The impact of diet on right ventricular systolic pressure and pulmonary vascular resistance was determined in vivo or in ex vivo isolated lungs, respectively, and correlated with alterations in the composition of the gut microbiome, plasma metabolome, pulmonary inflammatory cell phenotype, and lung proteome.

RESULTS

High-soluble-fiber diet increased the abundance of short-chain fatty acid-producing bacteria, with parallel increases in plasma propionate levels, and reduced the abundance of disease-related bacterial genera such as Staphylococcus, Clostridioides, and Streptococcus in hypoxic mice with parallel decreases in plasma levels of p-cresol sulfate. High-soluble-fiber diet decreased hypoxia-induced elevations of right ventricular systolic pressure and pulmonary vascular resistance. These changes were associated with reduced proportions of interstitial macrophages, dendritic cells, and nonclassical monocytes. Whole-lung proteomics revealed proteins and molecular pathways that may explain the effect of soluble-fiber supplementation.

CONCLUSIONS

This study demonstrates for the first time that a high-soluble-fiber diet attenuates hypoxia-induced pulmonary vascular remodeling and the development of pulmonary hypertension in a mouse model of hypoxic pulmonary hypertension and highlights diet-derived metabolites that may have an immuno-modulatory role in the lung.

Inhibition of pro-inflammatory signaling in human primary macrophages by enhancing arginase-2 via target site blockers

The modulation of macrophage phenotype from a pro-inflammatory to an anti-inflammatory state holds therapeutic potential in the treatment of inflammatory disease. We have previously shown that arginase-2 (Arg2), a mitochondrial enzyme, is a key regulator of the macrophage anti-inflammatory response. Here, we investigate the therapeutic potential of Arg2 enhancement via target site blockers (TSBs) in human macrophages. TSBs are locked nucleic acid antisense oligonucleotides that were specifically designed to protect specific microRNA recognition elements (MREs) in human ARG2 3' UTR mRNA. TSBs targeting miR-155 (TSB-155) and miR-3202 (TSB-3202) MREs increased ARG2 expression in human monocyte-derived macrophages. This resulted in decreased gene expression and cytokine production of TNF-α and CCL2 and, for TSB-3202, in an increase in the anti-inflammatory macrophage marker, CD206. Proteomic analysis demonstrated that a network of pro-inflammatory responsive proteins was modulated by TSBs. In silico bioinformatic analysis predicted that TSB-3202 suppressed upstream pro-inflammatory regulators including STAT-1 while enhancing anti-inflammatory associated proteins. Proteomic data were validated by confirming increased levels of sequestosome-1 and decreased levels of phosphorylated STAT-1 and STAT-1 upon TSB treatment. In conclusion, upregulation of Arg2 by TSBs inhibits pro-inflammatory signaling and is a promising novel therapeutic strategy to modulate inflammatory signaling in human macrophages.

Evaluating the effects of grass management technologies on the physical, environmental, and financial performance of Irish pasture-based dairy farms

Grass management technologies (grass measuring devices and grassland management decision support tools) have been identified as important tools to improve the performance of pasture-based dairy farms. They have the potential to significantly improve the efficiency and sustainability of dairy systems by increasing milk production through enhanced pasture growth and utilization, which would reduce the need for supplementary feeds, along with increased output, therefore increasing farm profitability and environmental sustainability. Despite the several potential benefits of grass management technologies, there is a lack of empirical research around the effects of these technologies on the performance of pasture-based dairy systems. The current study aimed to fill this knowledge gap by using a 2018 nationally representative survey of Irish dairy farms and a propensity score matching approach to determine the effects of adopting grass management technologies on the physical, environmental, and financial performance of Irish pasture-based dairy farms. The findings showed that dairy farms utilizing grass management technologies had, on average, higher farm physical, environmental, and financial performance (in terms of grazed pasture use, total pasture use, length of the grazing season, milk yield, milk solids, greenhouse gas emissions per kilogram of fat- and protein-corrected milk, gross output, and gross margin) compared with dairy farms not utilizing these technologies. However, when controlling for selection bias, we can only attribute a positive causal effect of grass management technology adoption on the use of grazed pasture per cow, grazing season length, milk yield per cow, and milk solids per cow. This might be due to dairy farmers not yet using the technologies to their full potential, 2018 being an unusual year in terms of weather (and therefore not being able to capture the full range of farm performance benefits), or because grass management technologies need to be adopted in association with other technologies and practices to achieve their expected performance outcomes. Future research should include updated farm-level data to capture the weather and learning effects and so be able to determine the impact of grass management technologies on a wider range of performance indicators.

Investigating serum extracellular vesicles in Cystic Fibrosis

BACKGROUND

Extracellular vesicles (EVs) are emerging as biomarkers of disease with diagnostic potential in CF. With the advent of highly effective modulator therapy, sputum production is less common and there is a need to identify novel markers of CF disease progression, exacerbation and response to therapies in accessible fluids such as serum.

METHODS

We used size exclusion chromatography (SEC) to isolate and characterise EVs from the blood of PWCF of different ages and compared to ultracentrifugation (UC). We used nanoparticle tracking analysis to measure the number of EVs present in serum obtained from children and adults with CF. Mass spectrometry based proteomics was used to characterise protein expression changes between the groups.

RESULTS

EVs were successfully isolated in SEC fractions from 250 µl serum from PWCF in greater numbers (p <0.01) than density ultracentrifugation. There was not a significant difference in EV numbers between young children with CF and controls. However, there was significantly more EVs in adults compared to children (<6yrs) (p < 0.05). EVs from PWCF before and after Kaftrio treatment were also analysed. Significant protein expression changes were observed within all 3 group. The largest changes detected were between children and adults with CF (57 proteins had a 1.5 fold change in expression with 19 significant changes p < 0.05) and PWCF taking Kaftrio (24 significant changes in EV protein expression was observed 12 months post treatment).

CONCLUSION

In this pilot study, we performed an initial characterisation of EVs in serum from PWCF demonstrating the potential of serum EVs for further diagnostic investigation.

Shear Stress Markedly Alters the Proteomic Response to Hypoxia in Human Pulmonary Endothelial Cells

Blood flow produces shear stress that homeostatically regulates the phenotype of pulmonary endothelial cells exerting anti-inflammatory and anti-thrombotic actions and maintaining normal barrier function. Hypoxia due to diseases, such as COPD, causes vasoconstriction, increased vascular resistance and pulmonary hypertension. Hypoxia-induced changes in endothelial function play a central role in the development of pulmonary hypertension. However, the interactive effects of hypoxia and shear stress on the pulmonary endothelial phenotype have not been studied. Human pulmonary microvascular endothelial cells were cultured in normoxia or hypoxia while subjected to physiological shear stress or in static conditions. Unbiased proteomics was used to identify hypoxia-induced changes in protein expression. Using publicly available scRNAseq datasets, differences in gene expression between the alveolar endothelial cells from COPD and healthy lungs were identified. 60 proteins were identified whose expression changed in response to hypoxia in conditions of physiological shear stress but not in static conditions. These included proteins that are crucial for endothelial homeostasis e.g. JAM-A, ERG or implicated in pulmonary hypertension e.g. thrombospondin-1. 55 of these 60 have not been previously implicated in the development of hypoxic lung diseases. mRNA for five of the 60 (ERG, MCRIP1, EIF4A2, HSP90AA1 and DNAJA1) showed similar changes in the alveolar endothelial cells of COPD compared to healthy lungs in females but not in males. These data show that the proteomic responses of the pulmonary microvascular endothelium to hypoxia are significantly altered by shear stress and suggest that these shear-hypoxia interactions are important in the development of hypoxic pulmonary vascular disease.

Protein with negative surface charge distribution, Bnr1, shows characteristics of a DNA-mimic protein and may be involved in the adaptation of Burkholderia cenocepacia

Adaptation of opportunistic pathogens to their host environment requires reprogramming of a vast array of genes to facilitate survival in the host. Burkholderia cenocepacia, a Gram-negative bacterium with a large genome of ∼8 Mb that colonizes environmental niches, is exquisitely adaptable to the hypoxic environment of the cystic fibrosis lung and survives in macrophages. We previously identified an immunoreactive acidic protein encoded on replicon 3, BCAS0292. Deletion of the BCAS0292 gene significantly altered the abundance of 979 proteins by 1.5-fold or more; 19 proteins became undetectable while 545 proteins showed ≥1.5-fold reduced abundance, suggesting the BCAS0292 protein is a global regulator. Moreover, the ∆BCAS0292 mutant showed a range of pleiotropic effects: virulence and host-cell attachment were reduced, antibiotic susceptibility was altered, and biofilm formation enhanced. Its growth and survival were impaired in 6% oxygen. In silico prediction of its three-dimensional structure revealed BCAS0292 presents a dimeric β-structure with a negative surface charge. The ΔBCAS0292 mutant displayed altered DNA supercoiling, implicated in global regulation of gene expression. Three proteins were identified in pull-downs with FLAG-tagged BCAS0292, including the Histone H1-like protein, HctB, which is recognized as a global transcriptional regulator. We propose that BCAS0292 protein, which we have named Burkholderia negatively surface-charged regulatory protein 1 (Bnr1), acts as a DNA-mimic and binds to DNA-binding proteins, altering DNA topology and regulating the expression of multiple genes, thereby enabling the adaptation of B. cenocepacia to highly diverse environments.

Differential Exoproteome and Biochemical Characterisation of Neoparamoeba perurans

Infection with the protozoan ectoparasite Neoparamoeba perurans, the causative agent of AGD, remains a global threat to salmonid farming. This study aimed to analyse the exoproteome of both an attenuated and virulent N. perurans isolate using proteomics and cytotoxicity testing. A disproportionate presence of proteins from the co-cultured microbiota of N. perurans was revealed on searching an amalgamated database of bacterial, N. perurans and Amoebozoa proteins. LC-MS/MS identified 33 differentially expressed proteins, the majority of which were upregulated in the attenuated exoproteome. Proteins of putative interest found in both exoproteomes were maltoporin, ferrichrome-iron receptor, and putative ferric enterobactin receptor. Protease activity remained significantly elevated in the attenuated exoproteome compared with the virulent exoproteome. Similarly, the attenuated exoproteome had a significantly higher cytotoxic effect on rainbow trout gill cell line (RTgill W1) cells compared with the virulent exoproteome. The presence of a phosphatase and serine protease in the virulent exoproteome may facilitate AGD infection but do not appear to be key players in causing cytotoxicity. Altogether, this study reveals prolonged culture of N. perurans affects the exoproteome composition in favour of nutritional acquisition, and that the current culturing protocol for virulent N. perurans does not facilitate the secretion of virulence factors.

Host Response of Atlantic Salmon (Salmo salar) Re-Inoculated with Paramoeba perurans

In aquaculture, recurrence rates of amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans are high and no prophylactic strategies exist for disease prevention. In this study, Atlantic salmon (Salmo salar) were initially inoculated with P. perurans and following the development of amoebic gill disease were treated with freshwater immersion on day 21 and day 35 post inoculation. Fish were re-inoculated following a negative qPCR analysis for the presence of P. perurans. The gill host immune response was investigated at 7, 14, and 18 days post re-inoculation. Differential proteome expression of immune related proteins was assessed by comparison of each time point against naïve controls. In the gill, some proteins of the innate immune system were expressed in response to gill re-colonization by P. perurans, while no features of adaptive immunity were found to be differentially expressed. Many of the proteins identified are novel in the context of AGD and their expression profiles suggest that their roles in the response to disease development and progression in single or multiple infections warrant further investigation.

Investigation of the Initial Host Response of Naïve Atlantic Salmon (Salmo salar) Inoculated with Paramoeba perurans

Amoebic Gill Disease (AGD), caused by the ectoparasite Paramoeba perurans is characterised by hyperplasia of the gill epithelium and lamellar fusion. In this study, the initial host response of naïve Atlantic salmon (Salmo salar) inoculated with P. perurans was investigated. Using gel-free proteomic techniques and mass spectrometry gill and serum samples were analysed at 7 timepoints (2, 3, 4, 7, 9, 11 and 14 days) post-inoculation with P. perurans. Differential expression of immune related proteins was assessed by comparison of protein expression from each time point against naïve controls. Few host immune molecules associated with innate immunity showed increased expression in response to gill colonisation by amoebae. Furthermore, many proteins with roles in immune signalling, phagocytosis and T-cell proliferation were found to be inhibited upon disease progression. Initially, various immune factors demonstrated the anticipated increase in expression in response to infection in the serum while some immune inhibition became apparent at the later stages of disease progression. Taken together, the pro-immune trend observed in serum, the lack of a robust early immune response in the gill and the diversity of those proteins in the gill whose altered expression negatively impact the immune response, support the concept of a pathogen-derived suppression of the host response.

Establishing nationally representative benchmarks of farm-gate nitrogen and phosphorus balances and use efficiencies on Irish farms to encourage improvements

Agriculture faces considerable challenges of achieving more sustainable production that minimises nitrogen (N) and phosphorus (P) losses and meets international obligations for water quality and greenhouse gas emissions. This must involve reducing nutrient balance (NB) surpluses and increasing nutrient use efficiencies (NUEs), which could also improve farm profitability (a win-win). To set targets and motivate improvements in Ireland, nationally representative benchmarks were established for different farm categories (sector, soil group and production intensity). Annual farm-gate NBs (kg ha^-1) and NUEs (%) for N and P were calculated for 1446 nationally representative farms from 2008 to 2015 using import and export data collected by the Teagasc National Farm Survey (part of the EU Farm Accountancy Data Network). Benchmarks for each category were established using quantile regression analysis and percentile rankings to identify farms with the lowest NB surplus per production intensity and highest gross margins (€ ha^-1). Within all categories, large ranges in NBs and NUEs between benchmark farms and poorer performers show considerable room for nutrient management improvements. Results show that as agriculture intensifies, nutrient surpluses, use efficiencies and gross margins increase, but benchmark farms minimise surpluses to relatively low levels (i.e. are more sustainable). This is due to, per ha, lower fertiliser and feed imports, greater exports of agricultural products, and for dairy, sheep and suckler cattle, relatively high stocking rates. For the ambitious scenario of all non-benchmark farms reaching the optimal benchmark zone, moderate reductions in farm nutrient surpluses were found with great improvements in profitability, leading to a 31% and 9% decrease in N and P surplus nationally, predominantly from dairy and non-suckler cattle. The study also identifies excessive surpluses for each level of production intensity, which could be used by policy in setting upper limits to improve sustainability.

Proteomic Analysis Reveals a Strong Association of β-Catenin With Cadherin Adherens Junctions in Resting Human Platelets

It was previously demonstrated that the WNT/β-catenin pathway is present and active in platelets and established that the canonical WNT ligand, WNT-3a, suppresses platelet adhesion and activation. In nucleated cells, β-catenin, the key downstream effector of this pathway, is a dual function protein, regulating the coordination of gene transcription and cell-cell adhesion. The specific role of β-catenin in the anucleate platelet however remains elusive. Here, a label-free quantitative proteomic analysis of β-catenin immunoprecipitates from human platelets is performed and nine co-immunoprecipitating proteins are identified. Three of the co-immunoprecipitating proteins (α-catenin-1, cadherin-6, and β-catenin-interacting protein 1) are common to both resting and activated conditions. Bioinformatics analysis of proteomics data reveal a strong association of the dataset with both cadherin adherens junctions and regulators of WNT signaling. It is then verified that platelet β-catenin and cadherin-6 interact and that this interaction is regulated by the activation state of the platelet. Taken together, this proteomics study suggests a novel role for β-catenin in human platelets where it interacts with platelet cadherins and associated junctional proteins.

SETD1A Methyltransferase Is Physically and Functionally Linked to the DNA Damage Repair Protein RAD18

SETD1A is a SET domain-containing methyltransferase involved in epigenetic regulation of transcription. It is the main catalytic component of a multiprotein complex that methylates lysine 4 of histone H3, a histone mark associated with gene activation. In humans, six related protein complexes with partly nonredundant cellular functions share several protein subunits but are distinguished by unique catalytic SET-domain proteins. We surveyed physical interactions of the SETD1A-complex using endogenous immunoprecipitation followed by label-free quantitative proteomics on three subunits: SETD1A, RBBP5, and ASH2L. Surprisingly, SETD1A, but not RBBP5 or ASH2L, was found to interact with the DNA damage repair protein RAD18. Reciprocal RAD18 immunoprecipitation experiments confirmed the interaction with SETD1A, whereas size exclusion and protein network analysis suggested an interaction independent of the main SETD1A complex. We found evidence of SETD1A and RAD18 influence on mutual gene expression levels. Further, knockdown of the genes individually showed a DNA damage repair phenotype, whereas simultaneous knockdown resulted in an epistatic effect. This adds to a growing body of work linking epigenetic enzymes to processes involved in genome stability.

Abstract 173: Sodium Salicylate Modulates Reverse Cholesterol Transport and HDL Proteome within Obesity

Obesity is associated with increased risk of cardiovascular disease (CVD) due to imbalances in lipid metabolism and leads to maladaptive inflammatory responses. This study assessed the effects of an obesogenic diet supplemented with anti-inflammatory sodium salicylate (NaS) on hepatic health, HDL proteomic quality, HDL functionality and Reverse Cholesterol Transport (RCT).

RCT was assessed after 24 weeks in C57BL/6 mice fed a high fat (HFD) (60% fat) ± NaS (6g/kg) diet or low-fat diet (LFD, 10% fat) by tracing 3 H-cholesterol movement from labelled macrophages, injected intraperitoneally, into plasma, liver and fecal compartments. HDL particles were separated from plasma by fast protein liquid chromatography (FPLC) and associated proteins were identified by mass spectrometry. HDL particles were incubated with 3 H-cholesterol-labelled macrophages ex vivo and cholesterol efflux to HDL particles was determined by liquid scintillation counting (LSC).

Both HFDs significantly increased HDL cholesterol mass. Nonetheless, HFD alone impaired hepatic movement of 3 H-cholesterol to fecal compartments coincident with increased hepatic lipid infiltration and inflammation. NaS supplementation increased all steps of macrophage-to-feces RCT with partial preservation of hepatic transporters while impeding hepatic lipid load and reducing markers of inflammation (ALT & AST). HFD resulted in enrichment of HDL particles with coagulant proteins (fibrinogen, coagulation factor IX) and a dissociation of anti-thrombin and angiotensinogen compared to HFD+NaS. NaS supplementation also preserved ABCA1-mediated efflux capacity of HDL particles.

Obesogenic diets augmented with NaS resulted in profound differences within the RCT pathway and HDL proteome. HFD supplemented with NaS was associated with improved hepatic condition and HDL proteomic profile with an increase of anticoagulant and anti-atherogenic proteins on HDL despite development of obesity.

The H3K36me2 Methyltransferase Nsd1 Demarcates PRC2-Mediated H3K27me2 and H3K27me3 Domains in Embryonic Stem Cells

The Polycomb repressor complex 2 (PRC2) is composed of the core subunits Ezh1/2, Suz12, and Eed, and it mediates all di- and tri-methylation of histone H3 at lysine 27 in higher eukaryotes. However, little is known about how the catalytic activity of PRC2 is regulated to demarcate H3K27me2 and H3K27me3 domains across the genome. To address this, we mapped the endogenous interactomes of Ezh2 and Suz12 in embryonic stem cells (ESCs), and we combined this with a functional screen for H3K27 methylation marks. We found that Nsd1-mediated H3K36me2 co-locates with H3K27me2, and its loss leads to genome-wide expansion of H3K27me3. These increases in H3K27me3 occurred at PRC2/PRC1 target genes and as de novo accumulation within what were previously broad H3K27me2 domains. Our data support a model in which Nsd1 is a key modulator of PRC2 function required for regulating the demarcation of genome-wide H3K27me2 and H3K27me3 domains in ESCs.

High-Density Lipoprotein Proteomic Composition, and not Efflux Capacity, Reflects Differential Modulation of Reverse Cholesterol Transport by Saturated and Monounsaturated Fat Diets

BACKGROUND

Acute inflammation impairs reverse cholesterol transport (RCT) and reduces high-density lipoprotein (HDL) function in vivo. This study hypothesized that obesity-induced inflammation impedes RCT and alters HDL composition, and investigated if dietary replacement of saturated (SFA) for monounsaturated (MUFA) fatty acids modulates RCT.

METHODS AND RESULTS

Macrophage-to-feces RCT, HDL efflux capacity, and HDL proteomic profiling was determined in C57BL/6j mice following 24 weeks on SFA- or MUFA-enriched high-fat diets (HFDs) or low-fat diet. The impact of dietary SFA consumption and insulin resistance on HDL efflux function was also assessed in humans. Both HFDs increased plasma (3)H-cholesterol counts during RCT in vivo and ATP-binding cassette, subfamily A, member 1-independent efflux to plasma ex vivo, effects that were attributable to elevated HDL cholesterol. By contrast, ATP-binding cassette, subfamily A, member 1-dependent efflux was reduced after both HFDs, an effect that was also observed with insulin resistance and high SFA consumption in humans. SFA-HFD impaired liver-to-feces RCT, increased hepatic inflammation, and reduced ABC subfamily G member 5/8 and ABC subfamily B member 11 transporter expression in comparison with low-fat diet, whereas liver-to-feces RCT was preserved after MUFA-HFD. HDL particles were enriched with acute-phase proteins (serum amyloid A, haptoglobin, and hemopexin) and depleted of paraoxonase-1 after SFA-HFD in comparison with MUFA-HFD.

CONCLUSIONS

Ex vivo efflux assays validated increased macrophage-to-plasma RCT in vivo after both HFDs but failed to capture differential modulation of hepatic cholesterol trafficking. By contrast, proteomics revealed the association of hepatic-derived inflammatory proteins on HDL after SFA-HFD in comparison with MUFA-HFD, which reflected differential hepatic cholesterol trafficking between groups. Acute-phase protein levels on HDL may serve as novel biomarkers of impaired liver-to-feces RCT in vivo.

Bacteriophage therapy to reduce Campylobacter jejuni colonization of broiler chickens

Colonization of broiler chickens by the enteric pathogen Campylobacter jejuni is widespread and difficult to prevent. Bacteriophage therapy is one possible means by which this colonization could be controlled, thus limiting the entry of campylobacters into the human food chain. Prior to evaluating the efficacy of phage therapy, experimental models of Campylobacter colonization of broiler chickens were established by using low-passage C. jejuni isolates HPC5 and GIIC8 from United Kingdom broiler flocks. The screening of 53 lytic bacteriophage isolates against a panel of 50 Campylobacter isolates from broiler chickens and 80 strains isolated after human infection identified two phage candidates with broad host lysis. These phages, CP8 and CP34, were orally administered in antacid suspension, at different dosages, to 25-day-old broiler chickens experimentally colonized with the C. jejuni broiler isolates. Phage treatment of C. jejuni-colonized birds resulted in Campylobacter counts falling between 0.5 and 5 log10 CFU/g of cecal contents compared to untreated controls over a 5-day period postadministration. These reductions were dependent on the phage-Campylobacter combination, the dose of phage applied, and the time elapsed after administration. Campylobacters resistant to bacteriophage infection were recovered from phage-treated chickens at a frequency of <4%. These resistant types were compromised in their ability to colonize experimental chickens and rapidly reverted to a phage-sensitive phenotype in vivo. The selection of appropriate phage and their dose optimization are key elements for the success of phage therapy to reduce campylobacters in broiler chickens.

Correlation of Campylobacter bacteriophage with reduced presence of hosts in broiler chicken ceca

Campylobacter jejuni and Campylobacter-specific bacteriophage were enumerated from broiler chicken ceca selected from 90 United Kingdom flocks (n = 205). C. jejuni counts in the presence of bacteriophage (mean log(10) 5.1 CFU/g) were associated with a significant (P < 0.001) reduction compared to samples with Campylobacter alone (mean log(10) 6.9 CFU/g).

Longitudinal study of Campylobacter jejuni bacteriophages and their hosts from broiler chickens

A longitudinal study of bacteriophages and their hosts was carried out at a broiler house that had been identified as having a population of Campylobacter-specific bacteriophages. Cloacal and excreta samples were collected from three successive broiler flocks reared in the same barn. Campylobacter jejuni was isolated from each flock, whereas bacteriophages could be isolated from flocks 1 and 2 but were not isolated from flock 3. The bacteriophages isolated from flocks 1 and 2 were closely related to each other in terms of host range, morphology, genome size, and genetic content. All Campylobacter isolates from flock 1 were genotypically indistinguishable by pulsed-field gel electrophoresis (PFGE). PFGE and multilocus sequence typing indicated that this C. jejuni type was maintained from flock 1 to flock 2 but was largely superseded by three genetically distinct C. jejuni types insensitive to the resident bacteriophages. All isolates from the third batch of birds were insensitive to bacteriophages and genotypically distinct. These results are significant because this is the first study of an environmental population of C. jejuni bacteriophages and their influence on the Campylobacter populations of broiler house chickens. The role of developing bacteriophage resistance was investigated as this is a possible obstacle to the use of bacteriophage therapy to reduce the numbers of campylobacters in chickens. In this broiler house succession was largely due to incursion of new genotypes rather than to de novo development of resistance.

Catecholamines in human saliva

Catecholamines are readily detectable in human saliva but their origin is unclear. Norepinephrine (NE) was stable in saliva stored at 4 degrees for 2 hours but 11 +/- 3% degraded after storage at 25 degrees for 1 hour. We intravenously infused 3H-NE into humans and measured levels of 3H-NE and its metabolites in both saliva and forearm venous plasma (a site whose plasma NE levels reflect both local uptake and release of NE). 3H-NE levels in saliva continued to rise for 1 hour even though forearm plasma levels had plateaued by 5 min. By 65 min into the infusion the ratio of 3H-NE:non-radioactive NE was similar in saliva and forearm venous plasma. The ratio of NE:epinephrine (E) was similar in saliva and forearm venous plasma at all time points. Chewing induced salivation, and at least tripled the amount of NE, E and 3H-NE released into saliva per minute, but decreased their concentration in saliva by as much as one half. Saliva NE level was unaltered after 15 min of standing but was increased by 31% after 1 hour of upright posture. Our data imply that the NE present in human saliva comes from both the bloodstream and from salivary sympathetic nerves. The finding that diffusion of blood NE into saliva takes roughly 1 hour to complete suggests that NE in saliva is a poor index of acute changes in sympathetic activity.

Congenital diaphragmatic herniation: antenatal detection and outcome

201 fetuses and babies with a congenital diaphragmatic herniation or eventration (referred to collectively as CDH) were notified to the Northern Region Congenital Abnormality Survey (NorCAS) in the 13-year period from 1985 to 1997, an incidence of 0.25 per 1000 births. The 1-year survival of all pregnancies associated with CDH was 37%. The 1-year survival of livebirths was 50%. Antenatal scan detected the diaphragmatic defect or associated structural abnormality in 50%. Another major structural abnormality was present in 62 (31%); one of these babies survived and 26 pregnancies were terminated. This group contained four of the six antepartum stillbirths, all three intrapartum stillbirths and four of the five spontaneous miscarriages. Non-isolated CDH occurred in association with Fryns (5), Goldenhar (1) and de Lange (1) syndromes, and in 16 of 17 with a chromosome anomaly. 53% of the 139 fetuses with isolated CDH survived to 1 year of age, and 59% of the 124 liveborn survived. Of 37 fetuses with isolated CDH detected before 25 weeks gestation, 12 pregnancies were terminated. There were 11 survivors among the 25 continuing pregnancies (44%). The overall survival of babies with CDH is very poor but, when a defect is identified by ultrasound before 25 weeks gestation, chromosome analysis and a careful ultrasound scan may suggest which fetuses have an isolated diaphragmatic abnormality and a greater chance of survival.

Serologic markers for Chlamydia pneumoniae in asthma

BACKGROUND

Chlamydia pneumoniae infection has been reported as a possible etiologic agent in asthma, which in primary care settings often appears to be initiated by acute respiratory infections.

OBJECTIVE

To determine if serologic markers for C. pneumoniae are associated with adult asthma that first became symptomatic after an acute respiratory illness (asthma associated with infection: AAWI).

METHODS

Serum samples from 164 primary care outpatients, mean age 44 years, (68 with AAWI; 36 with atopic, occupational or exercise-induced asthma (non-AAWI); 16 nonasthmatic patients with acute bronchitis; and 44 asymptomatic nonasthmatic controls) were tested for the presence of C. pneumoniae-specific IgG and IgA antibodies. Levels of chlamydial heat shock protein 60 (CHSP60) antibody were also measured. Those positive for CHSP60 were tested for C. pneumoniae-specific IgE antibodies by immunoblotting.

RESULTS

Statistically significant differences in IgG and IgA seroreactivity were noted between groups: acute bronchitis and AAWI had the highest levels (93% to 94% IgG seroreactivity, 69% to 75% IgA seroreactivity) whereas non-AAWI and asymptomatic controls had the lowest levels (61% to 84% IgG seroreactivity, 31% to 43% IgA seroreactivity, P < .02 after adjustment for age, sex and smoking). CHSP60 antibodies were significantly more prevalent in AAWI than in non-AAWI (19% versus 3%, P = .02). IgE antibodies against C. pneumoniae 60, 62, and/or 70 kD antigens were detected in 5 of 13 CHSP60 positive AAWI patients. Persistent IgG, IgA, and CHSP60 seroreactivities were noted in all seropositive asthma patients with serial serum samples.

CONCLUSIONS

Serologic markers of C. pneumoniae infection were associated with acute bronchitis and with asthma that first became symptomatic following respiratory illness. Serologic responses to C. pneumoniae may be useful in the classification and diagnosis of asthma.

Congenital anterior abdominal wall defects in the north of England, 1986-1996: occurrence and outcome

The aim was to describe trends in prevalence, maternal age-specific prevalence, associated anomalies, clinical outcomes and the sensitivity of antenatal diagnosis of congenital anterior abdominal wall defects (in particular gastroschisis and exomphalos). Data were identified from a population-based register of major congenital abnormalities in the Northern health region of England, the Northern Congenital Abnormality Survey (NorCAS), between 1986 and 1996. 296 cases were notified; there were 133 cases of gastroschisis, 98 exomphalos, 30 limb-body wall defects and 23 other anterior abdominal wall defects. 12 cases could not be classified. In 19 (6 per cent) the initial diagnosis was changed following case review. 30 (30.6 per cent) cases of exomphalos were associated with a chromosomal anomaly compared with 1 (0.8 per cent) case of gastroschisis. The total prevalence for the 11 years was 6.33 (95 per cent CI=5.57-7.08) per 10 000 live births, still births and terminations of pregnancy, and the overall birth prevalence was 4.30 (95 per cent CI=3.68-4.93) per 10 000 live births and still births. For gastroschisis, there was a significant increase over the study period in both the total prevalence (1.48 in 1986 to 5.29 per 10 000 in 1996; chi(2)=8.41, p=0.00433) and the birth prevalence (1.48 in 1986 to 4.72 per 10 000 in 1996; chi(2)=7.42, p=0.00644), but there was no such significant increase for exomphalos (total prevalence chi(2)=2.29, p=0.13055; birth prevalence chi(2)=0.16, p=0.69348). The maternal age-specific prevalence was highest in the 11-19 year age group for gastroschisis but in the 35-39 year age group for exomphalos. Fewer pregnancies with gastroschisis resulted in a termination and a greater proportion of cases were alive at one year compared with exomphalos. The sensitivity of abnormality detection by ultrasonography was 75 per cent and 77.3 per cent for gastroschisis and exomphalos, respectively. Antenatal diagnosis improved from 47.4 per cent during 1986-91 to 80 per cent between 1992-96 for gastroschisis (chi(2)=5.7, p=0.00169), and from 55.6 per cent to 68.8 per cent for isolated exomphalos, although this increase was not significant. Total and birth prevalence of gastroschisis increased in the Northern region between 1986 and 1996. For exomphalos, there was a trend towards an increase in total prevalence and towards a decrease in birth prevalence. This decreasing trend has been accompanied by improvements in antenatal detection and subsequent termination of cases of exomphalos associated with other anomalies.

A 10 year audit of antenatal ultrasound detection of renal disease

During a 10 year period, a renal tract anomaly was suspected on antenatal ultrasound in 125 fetuses, an incidence of five per 1000 births. 107 live births resulted. Three of six babies with renal failure were stented antenatally. A chromosome anomaly was present in three fetuses (2.4%). No live birth resulted in 14 pregnancies associated with oligohydramnios and no visible fetal bladder. Of those with renal agenesis or bilateral cystic dysplasia, one had a chromosome defect and a further four had extrarenal anomalies. Nine fetuses demonstrated isolated parenchymal hyperechogenicity and trisomy occurred in two of four with bilateral change in enlarged kidneys. All 14 babies with unilateral renal cysts had normal renal function postnatally, but only three of the cystic kidneys showed function. Antenatally, typical multicystic change was seen in 10, and smaller unevenly distributed cysts in four kidneys. Contralateral parenchymal echogenicity and/or pelvicalyceal distension indicating dysplasia was identified in four fetuses. Of 78 fetuses with isolated pelvic with or without calyceal distension the outcome was completely normal in 59% with unilateral, and in 48% with bilateral changes. One baby with unilateral and three with bilateral changes required dialysis or renal transplantation. One of four babies with antenatal ureteric distension had renal failure. Only one of six fetuses with bladder distension is alive in renal failure after in utero stenting.

L-selectin expression affects T-cell circulation following isoproterenol infusion in humans

beta-Adrenergic receptor agonists have been shown to affect leukocyte migration. This study examined the expression of cellular adhesion molecules on lymphocyte, monocyte, and granulocyte distribution following an infusion of isoproterenol (20 and 40 ng/kg/min for 15 min each) in 12 healthy subjects. Leukocyte populations and adhesion molecule expression were determined via flow cytometry. Isoproterenol led to an expected lymphocytosis and leukocytosis. L-selectin expression varied across leukocytes and influenced cell trafficking in response to isoproterenol. Approximately 60% of CD8+ T-cells expressed L-selectin (CD8+CD62L+) and these cells showed no appreciable response to isoproterenol. In contrast, CD8+CD62L- cells showed a robust increase in number and distribution of approximately 100% over baseline (p's < .001). Across CD4+ T-helpers, L-selectin was expressed on approximately 86% of cells. CD4+CD62L+ cells decreased in number and distribution (p's < .001) with isoproterenol, while CD4+CD62L- cells showed a modest increase (p's < or = .05). In contrast to lymphocytes, nearly all monocytes and granulocytes expressed L-selectin; these cells increased and decreased respectively in response to isoproterenol (p's < or = .05). CD11a (the beta 2-integrin LFA-1) was expressed on > 95% of all leukocytes and these data were thus similar to the overall leukocytosis data. CD54 (ICAM-1) was expressed on approximately 60% of mixed lymphocytes and was unchanged in response to isoproterenol. The findings indicate that L-selectin expression influences T-cell trafficking in response to beta-adrenergic stimulation and help further illuminate catecholamine-mediated sympathetic and immune interactions.

The antenatal diagnosis of fetal abnormalities: a 10 year audit of influencing factors

During the 10 years 1984-1993, a total of 438 fetuses and children with a congenital abnormality, identified antenatally or in the first year of life, were registered from the North Tees Health District with the Northern Region Congenital Abnormality Survey (NorCAS). This represented an abnormality rate of 2% of all births. In total, 252 structural abnormalities (57.5%) were detected by antenatal ultrasound examination. In spite of a targeted education programme, identification of cardiac lesions remained poor. The detection of structural abnormality by antenatal scan rose from 52% in 1984 to 85% in 1993, due mainly to improvements in image quality and resolution of ultrasound equipment. Also important was audit, based both on review of images and feedback from a comprehensive central register (NorCAS).

Race and sex differences in cardiovascular recovery from acute stress

To evaluate the effects of race and gender on recovery, i.e. the relative return to baseline after a stress challenge, cardiovascular and catecholamine measures were examined before, during and after two standardized laboratory stressors (a speaking and a mirror tracing task) in a group of 85 Black and White men and women (mean age 35.6 years, range 20 to 52). For the speech task, White men showed the least systolic (p < 0.025) and diastolic (p < 0.05) blood pressure recovery as compared to Black men and women. For the mirror star tracing task, total peripheral resistance (p < 0.03) recovery was least for Whites as compared to Blacks and heart rate (p < 0.04) recovery was least for White women as compared to Black women and men. There were no significant group effects in terms of catecholamine recovery from either task. The findings extend prior studies on race and gender by suggesting that these same characteristics affect recovery from stressors.

Psychologic characteristics associated with acute stressor-induced leukocyte subset redistribution

This study examined relationships between psychologic characteristics and enumerative immune responses to an acute laboratory stressor. Lymphocyte subsets were measured in 104 subjects at rest and following a 6-minute laboratory naturalistic speaking stressor. Multiple linear regression was utilized to assess relationships between immune reactivity (change scores) and anger expression, hostility, anxiety, depression, and stress. The task resulted in significant increases over baseline in WBC (p < 0.001), T-suppressor/cytotoxic CD8 cells (p = 0.010) natural killer CD56 cells (p < 0.0001), and CD57 (p < 0.0001) cells, and significant decreases in T-cells (p = 0.012), T-helper cells (p = 0.003), B-cells (p < 0.001), and the T-helper/suppressor ratio (p < 0.001). In general, the regression suggested that moderate associations exist between certain psychologic attributes and acute subset redistribution. For example, the increase in natural killer cell subsets was significantly negatively associated with anger expression, hostility, and depression. Suppressor/cytotoxic (CD8) cell reactivity was associated with baseline as well as with the task-induced changes in anxiety. B-cell (CD19) responses were related to the subject's age, expression of anger, and depression scores. As with the cardiovascular reactivity literature, these findings suggest that a relationship exists between certain psychologic characteristics such as anger and anxiety and immune reactivity to acute stress.

Menstrual cycle effects on catecholamine and cardiovascular responses to acute stress in black but not white normotensive women

This study examined cardiovascular and catecholamine responses to two standardized laboratory stressors in 33 healthy age- and weight-matched black and white normotensive women (mean age, 32 years) during two phases of the menstrual cycle. Subjects were studied in a randomized order at the same time of day on two separate occasions approximately six weeks apart, once during the follicular phase (days 7 to 10 after menses) and once during the luteal phase (days 7 to 10 after the leutenizing hormone surge) of the menstrual cycle. Black women has higher systolic (P=.01) and diastolic (P=.01) pressures compared with white women. Black women showed greater diastolic pressure (P <.01) and plasma epinephrine (P <.05) responses to stress during the follicular compared with the luteal phase of the menstrual cycle; white women showed no significant changes in these variables. The findings extend the literature on race differences in responsivity to stress and indicate that in contrast to white women, reproductive hormones do influence cardiovascular and catecholamine responsivity to stress in black women.

The antenatal diagnosis and management of abdominal wall defects: the northern region experience

One hundred and twenty abdominal wall defects were notified to the Northern Region Fetal Abnormality Survey in the five years 1988 to 1992. Gastroschisis occurred in 56, exomphalos in 43, amnion rupture in 11, ectopia vesicae in seven and ectopia cordis in three. Ultrasound failed to identify gastroschisis in 14 and incorrectly diagnosed exomphalos in eight. There was no associated chromosome abnormality and the survival rate, excluding first trimester loss, was 87%. Ultrasound failed to identify exomphalos in ten and incorrectly diagnosed gastroschisis in two. Another structural abnormality was present in 40% and a chromosome anomaly in 28%. Excluding spontaneous first trimester loss, the survival rate was 34%. Delivery of babies away from the regional paediatric surgical centre did not adversely affect the outcome in gastroschisis or exomphalos although closure was delayed, on average, by 2 h. There was one survivor of 11 fetuses with amnion rupture sequence. Six of the seven babies with ectopia vesicae and two of the three with ectopia cordis survived.

A technique for improved blood sampling during sleep studies

Research protocols often require that blood samples be drawn during sleep. This study compares the efficacy of obtaining nocturnal blood samples using a standard heparinized intravenous setup versus the same intravenous setup used in conjunction with a small chemical heating pad. The chemical heating pad significantly improved the number of blood samples obtained and the maintenance of intravenous patency. The use of a chemical heating pad is an economical way to resolve the frustration of lost blood samples while maintaining a reasonable environment to monitor sleep.

Effects of chronic stress on beta-adrenergic receptors in the homeless

This study examined the role of chronic life stress (homelessness), coping style, and hypertension on beta-adrenergic receptors in a sample of homeless men. Sixteen healthy normotensive subjects and nine untreated hypertensive subjects were studied. Life stress was measured with the Brown and Harris categorization; coping style was measured with the Ways of Coping Scale. Lymphocyte beta-adrenergic receptors were characterized in terms of receptor density (Bmax). Individuals with high life stress had lower Bmax (p < .005). In multiple regression analyses, 50% of the variance in Bmax was accounted for by life stress and coping style (p = .01). Receptor measures may be useful for characterizing the physiological response to continuing life adversity.

Case report: the antenatal ultrasound diagnosis of megalourethra

The antenatal ultrasound findings in a fetus which postnatally had fusiform megalourethra, rectal agenesis, recto-vesical fistula and unilateral renal hypoplasia are described. At 16 weeks gestation a cystic area was seen arising from the perineum. It later became evident that this was the urethra. Initially, an echogenic mass was noted in the pelvis, but by the second trimester, fluid-filled loops of bowel were evident. This combination of developmental abnormalities though rare is well defined. Only one previously recorded case has been suspected antenatally.

Antenatal detection of congenital diaphragmatic hernias: the northern region experience

This study analyses 7 years of data relating to congenital diaphragmatic herniation in the Northern Region. Ninety-nine confirmed cases were notified to the Northern Region Fetal Abnormality Survey between 1985 and 1991, which is an incidence of 0.35 per 1000 births. A specific diagnosis of CDH was made by antenatal ultrasound in 21 fetuses. The rate of detection improved from 6% to 41% but this had no impact on survival; severe pulmonary hypoplasia was found in the majority dying in the first 48 h. Another structural abnormality occurred in 29% and was the primary antenatal scan diagnosis in 11 fetuses. No other reliable indicator of outcome was identified, including the gestation when detected. The incidence of chromosomal abnormality was 5% and Fryns' syndrome 4%.

Does reactivity testing in the laboratory reflect blood pressure changes elsewhere?

This study examines whether reactivity testing in a laboratory setting might identify individuals whose blood pressure (BP) fluctuates excessively outside of the laboratory. Eighty-eight normotensive and untreated hypertensive patients were studied. Patients' BPs were obtained repeatedly on two separate screening occasions. They were subsequently admitted to a research ward, and 4 days later their BPs were measured at resting baseline and in response to a series of stressful tasks. Blood pressure declined by 14/11 mm Hg +/- 1.2/1.1 mm Hg (SE) from screening to the in-patient resting baseline. The four stressful tasks all led to increases in BP over the in-patient resting baseline level. Individuals with increased amounts of task-induced reactivity in the laboratory were also more likely to be those whose BP declined the most from out-patient screening to hospitalized baseline. The average correlation between the drop in BP associated with hospitalization and the BP reactivity to each stressor task was r = 0.33 for systolic BP (p < 0.01) and r = 0.24 for diastolic BP (p < 0.05). Reactivity responses in a laboratory setting may convey information about blood pressure fluctuation in the real world.

Noise-induced stress as a predictor of burnout in critical care nurses

In this study we found that, for 100 critical care nurses, noise-induced occupational stress was positively related to burnout as measured by Jones's Staff Burnout Scale for Health Professionals (r = 0.369, p less than 0.001) and the emotional exhaustion subscale of Maslach's Burnout Inventory (r = 0.300, p less than 0.01). Hierarchical multiple regressions confirmed these results once variance in burnout linked with life stressors and other occupational stressors was accounted for. Furthermore, an interaction term, noise-induced stress X intrinsic sensitivity to noise in the person, did not account for significant variance in burnout once independent variance linked with noise-induced stress was identified. That is, nurses with intrinsic sensitivity to noise were no more at risk for burnout linked with noise-induced stress than were less sensitive nurses. This result is discussed as evidence that there are exceptionally high levels of noise in critical care units. The critical care unit noises that are most distressing to nurses are identified and discussed in terms of stress theory.

The stress interview as a tool for examining physiological reactivity

Most studies of cardiovascular reactivity utilize tasks that are highly standardized and controlled. However, there is some concern whether the information obtained from these tasks is relevant to understanding the cardiovascular responses to behavioral stimuli encountered in real life. Historically, various forms of a stress interview have been used to examine physiological concomitants of emotional arousal. However, these tools fell into disuse because of ethical concerns, their intensive time requirements, and the perception that the interviews could not be standardized. We have developed a short (16-minute) interview that is not aversive or threatening. In studies on 24 normotensives and 19 hypertensives, the interview elicited greater blood pressure elevations than those elicited by mathematical calculations or cold pressor (p less than 0.0001). The interview increased systolic and diastolic pressures by 38/32 mm Hg in hypertensives and 31/24 mm Hg in normotensives. The variance in BP elicited by this interview is not appreciably greater than that found in highly structured tasks such as mathematical calculations. The test-retest stability of the interview is comparable to that of resting baseline blood pressure and is superior to that of mathematical calculations or cold pressor. Techniques such as the interview may be at least as useful as highly standardized tasks and possibly more valid as models for examining cardiovascular reactivity.

Ultrasonography, HIDA scintigraphy or both in the diagnosis of acute cholecystitis?

The benefit of early surgery for patients with acute cholecystitis is now accepted but rapid accurate pre-operative diagnosis is important and the single best investigation has not yet been clearly established. All 47 patients with suspected acute cholecystitis admitted to a district general hospital during a 6 month period underwent ultrasonic examination and scintigraphy with HIDA within 48 h of admission. In 23 patients acute cholecystitis was proven. Ultrasound correctly diagnosed this in 21 patients but in 2, changes attributed to chronic cholecystitis only were detected. Two false positive ultrasound results also occurred, one in a patient with adenomyomatosis and acute pancreatitis, the other in a case of duodenitis. HIDA scan was diagnostic in 19 patients but in the remaining 4 the presence of abnormal liver function tests accounted for non-visualization of the biliary tree (a non-diagnostic result). In the absence of jaundice a HIDA scan is the more specific test for confirming acute cholecystitis.

Low-frequency voltage noise in a mammalian bone cell clone

Measurements were made of plasma membrane voltage noise in cells of a bone cell clone. The measurements were made under conditions intended to approximate in vivo conditions more closely than in previous electrical measurements on small mammalian cells. Mononucleate cells of normal size, imbedded in a collagen matrix, were used. The electrical state of the cell membrane under normal conditions was characterized by low-frequency random fluctuations (noise) of high magnitude. Hyperpolarizing spikes were observed in some cells. Power spectrum analysis revealed that the random fluctuations were actually a sum of incoherent spike patterns, with spikes of the same time width as those seen in the clearly spiking patterns. This analysis, combined with similar measurements in a high [K+], low [Na+] medium, showed that the fluctuation/spiking phenomenon resulted from modulation of K+ and Na+ transport by a control process at a level higher than that of the individual channels. This process persisted when the membrane potential was depolarized. These results indicate that the membrane potential is not part of the feedback loop producing the fluctuation/spiking phenomenon.