A highly conserved complete accessory Escherichia coli type III secretion system 2 is widespread in bloodstream isolates of the ST69 lineage

Bacterial type III secretion systems (T3SSs) play an important role in pathogenesis of Gram-negative infections. Enteropathogenic and enterohemorrhagic Escherichia coli contain a well-defined T3SS but in addition a second T3SS termed E. coli T3SS 2 (ETT2) has been described in a number of strains of E. coli. The majority of pathogenic E. coli contain elements of a genetic locus encoding ETT2, but which has undergone significant mutational attrition rendering it without predicted function. Only a very few strains have been reported to contain an intact ETT2 locus. To investigate the occurrence of the ETT2 locus in strains of human pathogenic E. coli, we carried out genomic sequencing of 162 isolates obtained from patient blood cultures in Scotland. We found that 22 of 26 sequence type (ST) 69 isolates from this collection contained an intact ETT2 together with an associated eip locus which encodes putative secreted ETT2 effectors as well as eilA, a gene encoding a putative transcriptional regulator of ETT2 associated genes. Using a reporter gene for eilA activation, we defined conditions under which this gene was differentially activated. Analysis of published E. coli genomes with worldwide representation showed that ST69 contained an intact ETT2 in these strains as well. The conservation of the genes encoding ETT2 in human pathogenic ST69 strains strongly suggests it has importance in infection, although its exact functional role remains obscure.

IL-17 can be protective or deleterious in murine pneumococcal pneumonia

Streptococcus pneumoniae is the major bacterial cause of community-acquired pneumonia, and the leading agent of childhood pneumonia deaths worldwide. Nasal colonization is an essential step prior to infection. The cytokine IL-17 protects against such colonization and vaccines that enhance IL-17 responses to pneumococcal colonization are being developed. The role of IL-17 in host defence against pneumonia is not known. To address this issue, we have utilized a murine model of pneumococcal pneumonia in which the gene for the IL-17 cytokine family receptor, Il17ra, has been inactivated. Using this model, we show that IL-17 produced predominantly from γδ T cells protects mice against death from the invasive TIGR4 strain (serotype 4) which expresses a relatively thin capsule. However, in pneumonia produced by two heavily encapsulated strains with low invasive potential (serotypes 3 and 6B), IL-17 significantly enhanced mortality. Neutrophil uptake and killing of the serotype 3 strain was significantly impaired compared to the serotype 4 strain and depletion of neutrophils with antibody enhanced survival of mice infected with the highly encapsulated SRL1 strain. These data strongly suggest that IL-17 mediated neutrophil recruitment to the lungs clears infection from the invasive TIGR4 strain but that lung neutrophils exacerbate disease caused by the highly encapsulated pneumococcal strains. Thus, whilst augmenting IL-17 immune responses against pneumococci may decrease nasal colonization, this may worsen outcome during pneumonia caused by some strains.

Pharmacokinetics of intravenous lithium chloride and assessment of agreement between two methods of lithium concentration measurement in the horse

BACKGROUND

Pharmacokinetics of lithium chloride (LiCl) administered as a bolus, once i.v. have not been determined in horses. There is no point-of-care test to measure lithium (Li⁺ ) concentrations in horses in order to monitor therapeutic levels and avoid toxicity.

OBJECTIVES

To determine the pharmacokinetics of LiCl in healthy adult horses and to compare agreement between two methods of plasma Li⁺ concentration measurement: spectrophotometric enzymatic assay (SEA) and inductively coupled plasma mass spectrometry (ICP-MS).

STUDY DESIGN

Nonrandomised, single exposure with repeated measures over time.

METHODS

Lithium chloride was administered (0.15 mmol/kg bwt) as an i.v. bolus to eight healthy adult horses. Blood samples were collected pre-administration and at multiple times until 48 h post-administration. Samples were analysed by two methods (SEA and ICP-MS) to determine plasma Li⁺ concentrations. Pharmacokinetics were determined based on the reference ICP-MS data.

RESULTS

Adverse side effects were not observed. The SEA showed linearity, R² = 0.9752; intraday coefficient of variation, 2.5%; and recovery, 96.3%. Both noncompartmental and compartmental analyses (traditional two-stage and nonlinear mixed-effects [NLME] modelling) were performed. Geometric mean values of noncompartmental parameters were plasma Li⁺ concentration at time zero, 2.19 mmol/L; terminal elimination half-life, 25.68 h; area under the plasma concentration-time curve from time zero to the limit of quantification, 550 mmol/L min; clearance, 0.273 mL/min/kg; mean residence time, 31.22 h; and volume of distribution at steady state, 511 mL/kg. Results of the traditional two-stage analysis showed good agreement with the NLME modelling approach. Bland-Altman analyses demonstrated poor agreement between the SEA and ICP-MS methods (95% limits of agreement = 0.14 ± 0.13 mmol/L).

MAIN LIMITATIONS

Clinical effects of LiCl have not been investigated.

CONCLUSIONS

The LiCl i.v. bolus displayed pharmacokinetics similar to those reported in other species. The SEA displayed acceptable precision but did not agree well with the reference method (ICP-MS). The Summary is available in Spanish - see Supporting Information.

IL-17 signalling restructures the nasal microbiome and drives dynamic changes following Streptococcus pneumoniae colonization

Background

The bacterial pathogen Streptococcus pneumoniae colonizes the nasopharynx prior to causing disease, necessitating successful competition with the resident microflora. Cytokines of the IL-17 family are important in host defence against this pathogen but their effect on the nasopharyngeal microbiome is unknown. Here we analyse the influence of IL-17 on the composition and interactions of the nasopharyngeal microbiome before and after pneumococcal colonization.

Results

Using a murine model and 16S rRNA profiling, we found that a lack of IL-17 signalling led to profound alterations in the nasal but not lung microbiome characterized by decreased diversity and richness, increases in Proteobacteria and reduction in Bacteroidetes, Actinobacteria and Acidobacteria. Following experimental pneumococcal nasal inoculation, animals lacking IL-17 family signalling showed increased pneumococcal colonization, though both wild type and knockout animals showed as significant disruption of nasal microbiome composition, with increases in the proportion of Proteobacteria, even in animals that did not have persistent colonization. Sparse correlation analysis of the composition of the microbiome at various time points after infection showed strong positive interactions within the Firmicutes and Proteobacteria, but strong antagonism between members of these two phyla.

Conclusions

These results show the powerful influence of IL-17 signalling on the composition of the nasal microbiome before and after pneumococcal colonization, and apparent lack of interspecific competition between pneumococci and other Firmicutes. IL-17 driven changes in nasal microbiome composition may thus be an important factor in successful resistance to pneumococcal colonization and potentially could be manipulated to augment host defence against this pathogen.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4215-3) contains supplementary material, which is available to authorized users.

The interrelationship between phagocytosis, autophagy and formation of neutrophil extracellular traps following infection of human neutrophils by Streptococcus pneumoniae

Neutrophils play an important role in the innate immune response to infection with Streptococcus pneumoniae, the pneumococcus. Pneumococci are phagocytosed by neutrophils and undergo killing after ingestion. Other cellular processes may also be induced, including autophagy and the formation of neutrophil extracellular traps (NETs), which may play a role in bacterial eradication. We set out to determine how these different processes interacted following pneumococcal infection of neutrophils, and the role of the major pneumococcal toxin pneumolysin in these various pathways. We found that pneumococci induced autophagy in neutrophils in a type III phosphatidylinositol-3 kinase dependent fashion that also required the autophagy gene Atg5. Pneumolysin did not affect this process. Phagocytosis was inhibited by pneumolysin but enhanced by autophagy, while killing was accelerated by pneumolysin but inhibited by autophagy. Pneumococci induced extensive NET formation in neutrophils that was not influenced by pneumolysin but was critically dependent on autophagy. While pneumolysin did not affect NET formation, it had a potent inhibitory effect on bacterial trapping within NETs. These findings show a complex interaction between phagocytosis, killing, autophagy and NET formation in neutrophils following pneumococcal infection that contribute to host defence against this pathogen.

Lymphocytic foci in the endometrium of pregnant dairy cows: Characterization and association with reduced placental weight and embryonic loss

Lymphocytic foci (also known as lymphoid aggregates or tertiary lymphoid structures) form within the bovine endometrium after antigenic challenge. Their presence in the pregnant uterus provides evidence for a chronic inflammatory condition perhaps arising from an early postpartum uterine infection. The chronic inflammation that includes the foci could explain greater embryonic loss in dairy cows with early postpartum uterine disease. The objectives were to characterize the size and location of the foci in the pregnant uterus, determine their composition using immunohistochemistry, and associate their presence with the development of the pregnancy and embryonic loss. Pregnant cows (n = 43) were slaughtered on days 28, 35, or 42 of pregnancy. Uterine tissue was collected and processed for histologic and immunohistochemical analysis. The number of small (<100 micron diameter), intermediate (100-250 micron diameter), and large (>250 micron diameter) foci was counted. The number of cows averaging 0, 0.1 to 1, 1.1 to 2, and more than 2 foci per section (small, intermediate, and large; combined) was 7 (16%), 14 (33%), 11 (26%), and 11 (26%), respectively. The average number of small and intermediate foci found in the histologic sections was greater in cows with evidence of uterine infection postpartum (P < 0.05). Lymphocytic foci were distributed within the caruncle and the intercaruncular tissue and comprised a core of CD3-positive cells (T cells) surrounding CD79-positive cells (B cells). The number of lymphocytic foci was correlated with a total inflammation score (on the basis of the total number of inflammatory cells in the endometrium; r(2) = 0.49; P < 0.001) and a fibrosis score (based on the extent of fibrosis in the endometrium; r(2) = 0.33; P < 0.001). Cows with a high foci count (averaging more than 0.5 foci per section) had lesser (P < 0.01) placental weight on Day 42 of pregnancy. There was no effect of foci count on placental weight on Day 28 or 35. Two cows with embryonic loss were in the highest quartile for foci count. In conclusion, cows with chronic inflammation as evidenced by a large number of lymphocytic foci had reduced placental weight during pregnancy. The number of foci in pregnant cows was associated with early postpartum uterine disease. Whether the foci themselves are inhibitory to pregnancy development or are associated with other bacteriological, morphological, or biochemical changes to the uterus that lead to infertility will need to be investigated.

T helper cell subsets specific for Pseudomonas aeruginosa in healthy individuals and patients with cystic fibrosis

Background

We set out to determine the magnitude of antigen-specific memory T helper cell responses to Pseudomonas aeruginosa in healthy humans and patients with cystic fibrosis.

Methods

Peripheral blood human memory CD4⁺ T cells were co-cultured with dendritic cells that had been infected with different strains of Pseudomonas aeruginosa. The T helper response was determined by measuring proliferation, immunoassay of cytokine output, and immunostaining of intracellular cytokines.

Results

Healthy individuals and patients with cystic fibrosis had robust antigen-specific memory CD4⁺ T cell responses to Pseudomonas aeruginosa that not only contained a Th1 and Th17 component but also Th22 cells. In contrast to previous descriptions of human Th22 cells, these Pseudomonal-specific Th22 cells lacked the skin homing markers CCR4 or CCR10, although were CCR6⁺. Healthy individuals and patients with cystic fibrosis had similar levels of Th22 cells, but the patient group had significantly fewer Th17 cells in peripheral blood.

Conclusions

Th22 cells specific to Pseudomonas aeruginosa are induced in both healthy individuals and patients with cystic fibrosis. Along with Th17 cells, they may play an important role in the pulmonary response to this microbe in patients with cystic fibrosis and other conditions.

Rapidly building global health security capacity--Uganda demonstration project, 2013

Increasingly, the need to strengthen global capacity to prevent, detect, and respond to public health threats around the globe is being recognized. CDC, in partnership with the World Health Organization (WHO), has committed to building capacity by assisting member states with strengthening their national capacity for integrated disease surveillance and response as required by International Health Regulations (IHR). CDC and other U.S. agencies have reinforced their pledge through creation of global health security (GHS) demonstration projects. One such project was conducted during March-September 2013, when the Uganda Ministry of Health (MoH) and CDC implemented upgrades in three areas: 1) strengthening the public health laboratory system by increasing the capacity of diagnostic and specimen referral networks, 2) enhancing the existing communications and information systems for outbreak response, and 3) developing a public health emergency operations center (EOC) (Figure 1). The GHS demonstration project outcomes included development of an outbreak response module that allowed reporting of suspected cases of illness caused by priority pathogens via short messaging service (SMS; i.e., text messaging) to the Uganda District Health Information System (DHIS-2) and expansion of the biologic specimen transport and laboratory reporting system supported by the President's Emergency Plan for AIDS Relief (PEPFAR). Other enhancements included strengthening laboratory management, establishing and equipping the EOC, and evaluating these enhancements during an outbreak exercise. In 6 months, the project demonstrated that targeted enhancements resulted in substantial improvements to the ability of Uganda's public health system to detect and respond to health threats.

Copper toxicosis in New Zealand White rabbits (Oryctolagus cuniculus)

Six 12- to 14-month-old New Zealand White rabbits were diagnosed with copper toxicosis. These rabbits were part of a group of 110 purchased and shipped overnight for research purposes. On arrival, the group experienced an abrupt diet change. Eight died over 3 weeks and 6 were submitted for postmortem examination. Microscopic findings included severe centrilobular to midzonal hepatocellular necrosis with rhodanine stain-positive copper granules in the remaining hepatocytes. Mild periportal fibrosis and biliary hyperplasia, hemoglobinuric nephrosis, and splenic erythrophagocytosis were also observed. Hepatic copper concentrations were elevated, ranging from 319 to 997 ppm. Clinical disease was not previously observed in younger rabbits gradually transitioned from the supplier's copper-supplemented diet. Copper toxicosis likely occurred in these rabbits from a combination of (1) increased duration of copper supplementation leading to increased hepatocellular stores and (2) stress leading to anorexia and release of hepatocellular copper stores similar to chronic copper toxicosis as described in sheep.

Use of different levels of ground endophyte-infected tall fescue seed during heat stress to separate characteristics of fescue toxicosis

Studies of fescue toxicosis using whole seed diets show reduced feed intake and thermoregulatory ability, but much of the seed passes undigested through the animal. Cattle were fed ground tall fescue seed at different levels to potentially facilitate digestion and absorption of toxins and identify toxin sensitivity for major characteristics of the condition [i.e., hyperthermia, reduced feed intake (FI), reduced blood prolactin]. Steers (n = 18; 350 kg BW) were housed in the Brody Climatology Laboratory at thermoneutrality (TN; 19°C) and randomly assigned to daily diet treatments with either ground endophyte-infected [E+; low and high doses at 20 and 40 μg ergovaline/(kg BW/d), respectively] or endophyte-free [E-; control at 0 μg ergovaline/(kg BW/d)] tall fescue seed. After 12 d at TN, animals received 2 d of transition to heat stress (HS; 36°C daytime, 25°C nighttime) and maintained for 14 more days. Cattle were fed twice daily at 0800 and 1600 h, with water ad libitum. Feed intake was measured at 0700 h, with skin and rectal temperatures, and respiration rate at 0600, 1100, 1600, and 2100 h. Blood was sampled on selected days for prolactin and leptin determinations. Steers fed ground E+ diet decreased (P ≤ 0.0001) FI below controls at TN, with no dose effect. Maximum FI reduction with E+ treatment was 25% at TN, with an additional 46% decrease during HS (P ≤ 0.05). By the end of HS, E+ FI increased (P > 0.05) to that of E-, suggesting recovery. Prolactin was reduced (P ≤ 0.05) in high E+ cattle below controls at study end. Leptin blood concentrations were unaffected by E+ treatment (P > 0.05) but was reduced (P ≤ 0.05) by the end of HS. Pattern of rectal temperature response to HS showed a more rapid initial increase and decline for both E+ groups compared with controls (P ≤ 0.05). Skin temperature was the only variable that identified E+ dose differences. Although there were no treatment differences at TN, skin temperature was lower (P ≤ 0.05) for high E+ steers compared with controls during HS when air temperature was reduced each day. In general, FI was more responsive to E+ toxins than body temperature or blood prolactin, declining even at TN and exhibiting dynamic activity during HS. Although body temperature response to E+ toxins appears to stabilize during HS, this is misleading as rapid change in air temperature exposes effects on skin temperature.

Management of suspected Lyme borreliosis: experience from an outpatient parenteral antibiotic therapy service

OBJECTIVES

Lyme borreliosis (LB) is the most common human tick-borne infection in Europe and the USA. In this study we set out to analyse the outcome of patients treated for Lyme disease via outpatient parenteral antibiotic therapy (OPAT) and the appropriateness of this treatment using current guidelines.

METHODS

This was a retrospective review of all patients with suspected LB managed via OPAT in Glasgow in 2000-11.

RESULTS

Of 72 patients treated for suspected LB, 35 patients (49%) were treated in accordance with guidelines and 36 (50%) were treated with no specific guidelines. A definite improvement was seen in 20 patients (28%). Adverse reactions were documented in 29 (40%) patients with neutropenia, and mild liver function derangement was most commonly observed.

CONCLUSION

These results show the complexity of translating well-substantiated regimens from clinical trials to actual clinical practice. OPAT was an effective way of administering parenteral therapy for Lyme disease but should not be undertaken lightly due to the rate of adverse events and low rates of success in certain patient groups seen in this study. In view of this, stricter criteria for inclusion to OPAT in line with published guidance should be applied to minimize patient harm and optimize success.

Expression and regulation of the Escherichia coli O157:H7 effector proteins NleH1 and NleH2

BACKGROUND

E. coli O157 carries two genes encoding the effector proteins NleH1 and NleH2 which are 87% identical. Despite the similarity between the proteins, the promoter regions upstream of the genes encoding the effectors are more divergent suggesting that the actual expression of the genes may be differentially regulated. This was tested by creating reporter fusions and examining their expression in different genetic backgrounds, media and on contact with host cells. The function of the proteins was also tested following transfection into host cells.

PRINCIPAL FINDINGS

Expression of both NleH1 and NleH2 was enhanced when cultured under conditions that stimulated expression of the Type Three Secretion System (T3SS) and was influenced by the regulators Ler and GrlA. Maximal expression of NleH1 required 531 bp of the upstream untranslated region but NleH2 required only 113 bp. Interestingly, contact with host cells strongly repressed expression of both NleH1 and NleH2. Following transfection, both proteins produced only minor effects on NF-κB activation when assessed using a NF-κB luciferase reporter assay, a result that is consistent with the recent report demonstrating the dependence on RPS3 for NleH1 modulation of NF-κB.

SIGNIFICANCE

This study demonstrates the importance of considering gene regulation when studying bacterial effector proteins. Despite their sequence similarity, NleH1 and NleH2 are expressed differentially and may, therefore, be translocated at distinct times during an infection.

What is different about serotype 1 pneumococci?

Serotype 1 Streptococcus pneumoniae is among the most commonly isolated serotype in invasive pneumococcal disease but is rarely found causing asymptomatic nasopharyngeal colonization. Compared to infection by other serotypes, infection caused by serotype 1 is more likely to be identified in young patients without comorbidities but is generally associated with a lower mortality. Empyema and extrapulmonary manifestations are common. Outbreaks of serotype 1 disease have been reported in closed communities and epidemics are particularly common in sub-Saharan Africa. The serotype 1 capsular polysaccharide is a zwitterionic structure that enables it to function as a T-cell dependent antigen under some circumstances, in contrast to other pneumococcal capsular polysaccharides that are T-cell independent antigens. There are also differences in the key virulence factor pneumolysin in some serotype 1 isolates. The clinical significance of these differences remains to be determined.

Pseudomonas aeruginosa pilin activates the inflammasome

IL-1β is produced from inactive pro-IL-1β by activation of caspase-1 brought about by a multi-subunit protein platform called the inflammasome. Many bacteria can trigger inflammasome activity through flagellin activation of the host protein NLRC4. However, strains of the common human pathogen Pseudomonas aeruginosa lacking flagellin can still activate the inflammasome. We set out to identify what non-flagellin components could produce this activation. Using mass spectroscopy, we identified an inflammasome-activating factor from P. aeruginosa as pilin, the major component of the type IV bacterial pilus. Purified pilin introduced into mouse macrophages by liposomal delivery activated caspase-1 and led to secretion of mature IL-1β, as did recombinant pilin purified from Escherichia coli. This was dependent on caspase-1 but not on the host inflammasome proteins NLRC4, NLRP3 or ASC. Mutants of P. aeruginosa strain PA103 lacking pilin did not activate the inflammasome following infection of macrophages with live bacteria. Type III secretion remained intact in the absence of pili, showing this was not due to a lack of effector delivery. Our observations show pilin is a novel activator of the inflammasome in addition to flagellin and the recently described PrgJ protein family, the basal body rod component of the type III apparatus.

The role of potassium in inflammasome activation by bacteria

Many Gram-negative bacteria possess a type III secretion system (TTSS( paragraph sign)) that can activate the NLRC4 inflammasome, process caspase-1 and lead to secretion of mature IL-1beta. This is dependent on the presence of intracellular flagellin. Previous reports have suggested that this activation is independent of extracellular K(+) and not accompanied by leakage of K(+) from the cell, in contrast to activation of the NLRP3 inflammasome. However, non-flagellated strains of Pseudomonas aeruginosa are able to activate NLRC4, suggesting that formation of a pore in the cell membrane by the TTSS apparatus may be sufficient for inflammasome activation. Thus, we set out to determine if extracellular K(+) influenced P. aeruginosa inflammasome activation. We found that raising extracellular K(+) prevented TTSS NLRC4 activation by the non-flagellated P. aeruginosa strain PA103DeltaUDeltaT at concentrations above 90 mm, higher than those reported to inhibit NLRP3 activation. Infection was accompanied by efflux of K(+) from a minority of cells as determined using the K(+)-sensitive fluorophore PBFI, but no formation of a leaky pore. We obtained exactly the same results following infection with Salmonella typhimurium, previously described as independent of extracellular K(+). The inhibitory effect of raised extracellular K(+) on NLRC4 activation thus reflects a requirement for a decrease in intracellular K(+) for this inflammasome component as well as that described for NLRP3.

Phage-selected lipopolysaccharide mutants of Pectobacterium atrosepticum exhibit different impacts on virulence

AIMS

To positively select Pectobacterium atrosepticum (Pa) mutants with cell surface defects and to assess the impact of these mutations on phytopathogenesis.

METHODS AND RESULTS

Several phages were isolated from treated sewage effluent and were found to require bacterial lipopolysaccharide (LPS) for infection. Two strains with distinct mutations in LPS were obtained by transposon mutagenesis. Along with a third LPS mutant, these strains were characterized with respect to various virulence-associated phenotypes, including growth rate, motility and exoenzyme production, demonstrating that LPS mutations are pleiotropic. Two of the strains were deficient in the synthesis of the O-antigen portion of LPS, and both were less virulent than the wild type. A waaJ mutant, which has severe defects in LPS biosynthesis, was dramatically impaired in potato tuber rot assays. The infectivity of these novel phages on 32 additional strains of Pa was tested, showing that most Pa isolates were sensitive to the LPS-dependent phages.

CONCLUSIONS

Native LPS is crucial for optimal growth, survival and virulence of Pa in vivo, but simultaneously renders such strains susceptible to phage infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work demonstrates the power of phages to select and identify the virulence determinants on the bacterial surface, and as potential biocontrol agents for Pa infections.

Characterization of a broad-host-range flagellum-dependent phage that mediates high-efficiency generalized transduction in, and between, Serratia and Pantoea

A phage (PhiOT8) isolated on Serratia sp. ATCC 39006 was shown to be flagellum-dependent, and to mediate generalized transduction with high efficiency (up to 10(-4) transductants per p.f.u.). PhiOT8 was shown to have a broad host range because it also infected a strain of Pantoea agglomerans isolated from the rhizosphere. Transduction of plasmid-borne antibiotic resistance between the two bacterial genera was demonstrated, consistent with purported ecological roles of phages in dissemination of genes between bacterial genera. Serratia sp. ATCC 39006 and P. agglomerans produce a number of interesting secondary metabolites that have potential applications in cancer therapy and biocontrol of fungal infections. PhiOT8 has utility as a powerful functional genomics tool in these bacteria.

Exploitation of a new flagellatropic phage of Erwinia for positive selection of bacterial mutants attenuated in plant virulence: towards phage therapy

AIMS

To isolate and characterize novel bacteriophages for the phytopathogen, Erwinia carotovora ssp. atroseptica (Eca), and to isolate phage-resistant mutants attenuated in virulence.

METHODS AND RESULTS

A novel flagellatropic phage was isolated on the potato-rotting bacterial species, Eca, and characterized using electron microscopy and restriction analysis. The phage, named PhiAT1, has an icosahedral head and a long, contractile tail; it belongs to the Myoviridae family. Partial sequencing revealed the presence of genes with homology to those of coliphages T4, T7 and Mu. Phage-resistant transposon mutants of Eca were isolated and studied in vitro for a number of virulence-related phenotypes; only motility was found to be affected. In vivo tuber rotting assays showed that these mutants were attenuated in virulence, presumably because the infection is unable to spread from the initial site of inoculation.

CONCLUSIONS

The Eca flagellum can act as a receptor for PhiAT1 infection, and resistant mutants are enriched for motility and virulence defects.

SIGNIFICANCE AND IMPACT OF THE STUDY

PhiAT1 is the first reported flagellatropic phage found to infect Eca and has enabled further study of the virulence of this economically important phytopathogen.

Effects of the type III secreted pseudomonal toxin ExoS in the yeast Saccharomyces cerevisiae

Pseudomonas aeruginosa secretes a number of toxins by a type III system, and these are important in virulence. One of them, ExoS, is a bifunctional toxin, with a GTPase-activating protein domain, as well as ADP ribosyltransferase (ADPRT) activity. These two domains have numerous potential cellular targets, but the overall mechanism of ExoS action remains unclear. The effects of ExoS in a simple eukaryotic system, the yeast Saccharomyces cerevisiae, using a tetracycline-regulated expression system were studied. This system allowed controlled expression of ExoS in yeast, which was not possible using a galactose-induced system. ExoS was found to be an extremely potent inhibitor of yeast growth, and to be largely dependent on the activity of its ADPRT domain. ExoS produced a dramatic alteration in actin distribution, with the appearance of large aggregates of cortical actin, and thickened disorganized cables, entirely dependent on the ADPRT domain. This phenotype is suggestive of actin stabilization, which was verified by showing that the cortical aggregates of actin induced by ExoS were resistant to treatment with latrunculin A, an agent that prevents actin polymerization. ExoS increased the numbers of mating projections produced following growth arrest with mating pheromone, and prevented subsequent DNA replication, an effect that is again dependent on the ADPRT domain. Following pheromone removal, ExoS produced altered development of the mating projections, which became elongated with a swollen bud-like tip. These results suggest alternative pathways for ExoS action in eukaryotic cells that may result from activation of small GTPases, and this yeast expression system is well suited to explore these pathways.

Eukaryotic localization, activation and ubiquitinylation of a bacterial type III secreted toxin

Type III secretion is a widespread method whereby Gram-negative bacteria introduce toxins into eukaryotic cells. These toxins mimic or subvert a normal cellular process by interacting with a specific target, although how toxins reach their site of action is unclear. We set out to investigate the intracellular localization of a type III toxin of Pseudomonas aeruginosa called ExoU, which has phospholipase activity and requires a eukaryotic factor for activity. We found that ExoU is localized to the plasma membrane and undergoes modification within the cell by addition of two ubiquitin molecules at lysine-178. A region of five amino acids at position 679-683 near the C-terminus of the ExoU protein controls both membrane localization and ubiquitinylation. Site-directed mutagenesis identified a tryptophan at position 681 as crucial for these effects. We found that the same region at position 679-683 was also required for cell toxicity produced by ExoU as well as in vitro phospholipase activity. Localization of the phospholipase ExoU to the plasma membrane is thus required for activation and allows efficient utilization of adjacent substrate phospholipids.

Equine endometrial fibrosis correlates with 11beta-HSD2, TGF-beta1 and ACE activities

Endometrial periglandular fibrosis (EPF) contributes to embryonic and fetal loss in mares. Equine EPF correlates inversely with conception and successful gestation. In the modified Kenney endometrial biopsy classification system, EPF categories I, IIA, IIB, and III correspond to minimal, mild, moderate, and severe fibrosis (+/-inflammation), respectively. Paraffin sections of biopsy specimens were stained with H&E, and picrosirius red (specific for fibrillar collagens types I and III), to determine %EPCVF. Endometrial ACE-binding activity, TGF-beta1 and 11beta-HSD2 activities were also measured. Ultrastructural changes in EPF categories IIB and III endometria strongly suggested myofibroblastic transformation. ACE-binding activity was highest in EPF category IIB; however, endometrial TGF-beta1 and 11beta-HSD2 activities were significantly correlated to the severity of EPF (P<0.05). We conclude that, locally generated angiotensin II initiates the expression of TGF-beta1 resulting in myofibroblastic transformation. 11Beta-HSD2 in concert appears to modulate the severity of endometrial fibrosis.

Expression and Functions of the Duodenal Peptide Secretin and its Receptor in Human Lung

The physiological role of the duodenal peptide secretin is as a potent stimulant of electrolyte and water movement in pancreatic and biliary epithelium, via activation of G protein-coupled secretin receptors (hSCTR). However, the distribution and potential function of hSCTR in human lung has not previously been addressed. Using real-time quantitative reverse transcriptase-polymerase chain reaction profiling, in situ hybridization, and immunohistochemistry, we demonstrated that the hSCTR is abundantly expressed within the distal regions of human lung (tertiary bronchus and parenchyma), with negligible expression detected in more proximal regions (trachea, primary, and secondary bronchus). Expression was observed predominantly on the basolateral membrane of the bronchial epithelial layer, with some expression also observed in bronchial smooth muscle. In primary cultures of human tertiary bronchial epithelial cells, secretin was demonstrated to potently stimulate channel-mediated Cl- efflux in a concentration-dependent manner. Secretin was also shown to cause concentration-dependent relaxation of human tertiary bronchial smooth muscle. In summary, these data demonstrate that secretin receptors are present in human lung, and that activation of these receptors with human secretin potently stimulates concentration-dependent Cl- efflux from bronchial epithelial cells and bronchorelaxation.

Validation of the in vitro gastrointestinal (IVG) method to estimate relative bioavailable lead in contaminated soils

The effect of the dosing vehicle (e.g., dough) on the ability of an in vitro gastrointestinal (IVG) method to predict relative bioavailable Pb associated with soil ingestion was evaluated. Bioaccessible Pb determined by the IVG method was compared with relative bioavailable Pb measured from dosing trials using juvenile swine for 18 contaminated soils ranging from 1270 to 14200 mg Pb kg(-1). Bioaccessible Pb was measured in the IVG gastric extraction (GE) and intestinal extraction (IE) solutions. Mean bioaccessible Pb values were 32.2% for GE without dough, 23.0% for GE with dough, 1.06% for IE without dough, and 0.56% for IE with dough. It is possible that phytic acid associated with the dough addition decreased bioaccessible Pb. In vivo relative bioavailable Pb ranges for different swine tissues were 1 to 87% for blood, 0 to 110% for liver, 1 to 124% for kidney, and 0.04 to 94% for bone. Strong linear relationships between IVG GE Pb with dough (r > 0.76, P < 0.0002), IVG IE Pb with dough (r > 0.56, P < 0.015), and IVG GE Pb without dough (r > 0.81, P < 0.0001) and in vivo bioavailable Pb as estimated with blood, kidney, liver, and bone were found. Inexpensive in vitro methods may be useful in providing an estimate of the variability in relative bioavailable Pb at a single study site. The IVG method can be used to estimate relative bioavailable Pb, As, and Cd in contaminated soil.

3-methylindole induces transient olfactory mucosal injury in ponies

Response to 3-methylindole (3MI) varies among species. Mice recover from 3MI-induced bronchiolar epithelial injury but sustain persistent olfactory mucosal injury with scarring and epithelial metaplasia. In contrast, 3MI induces obliterative bronchiolitis in horses and ponies, but olfactory mucosal injury has not been reported. To evaluate the effect of 3MI on equine olfactory mucosa, ponies were dosed orally with 100 mg 3MI/kg (n = 9) or corn oil vehicle (n = 6). All ponies treated with 3MI developed obliterative bronchiolitis with mild olfactory injury. By 3 days after 3MI dosing, olfactory epithelium appeared disorganized with decreased and uneven surface height and scalloping of the basement membrane zone. Epithelial cells of Bowman's glands were hypertrophic. Proliferation of olfactory epithelium and Bowman's glands was supported by an increased mitotic index and positive immunohistochemical staining for proliferating cell nuclear antigen as compared with controls. The activity of 11beta-hydroxysteroid dehydrogenase, an olfactory mucosal cytosolic enzyme localized to sustentacular and Bowman's glandular epithelial cells, was concurrently decreased. By 9 days postdosing, olfactory mucosal lesions had lessened. Results indicate that 3MI transiently injures equine olfactory mucosa without the extensive necrosis, scarring, or metaplasia seen in murine olfactory mucosa or in equine bronchiolar epithelium.

Macrophage nitric oxide synthase associates with cortical actin but is not recruited to phagosomes

Nitric oxide (NO) produced from inducible NO synthase (iNOS) is an important component of host defense against intracellular pathogens. To understand how phagocytes deliver NO to ingested microorganisms while avoiding cytotoxicity, we set out to study the subcellular localization of iNOS within macrophages following phagocytosis. Confocal microscopy of immunostained cells showed that iNOS was located not only diffusely within cytoplasm but also in vesicles, as well as immediately adjacent to the peripheral cell membrane. This peripheral iNOS colocalized with the cortical actin cytoskeleton and was removed by the actin-depolymerizing drug cytochalasin B. Biochemical fractionation of RAW 264 macrophages showed that 32.75% (+/-5.11%; n = 3) of iNOS was present in a particulate fraction, which cosedimented with low-density cellular vesicles. Following phagocytosis of latex beads, zymosan, immunoglobulin G-coated beads, or complement-coated zymosan, submembranous cortical iNOS was not recruited to phagosomes, nor was there any relocalization of intracellular iNOS. Similarly, following phagocytosis of Salmonella enterica serovar Typhimurium there was no recruitment of iNOS to the Salmonella vacuole at any stage after internalization. NO mediated significant killing of intracellular S. enterica serovar Typhimurium in RAW macrophages treated with lipopolysaccharide and gamma interferon; this was evident 4 h after infection. Although not recruited to phagosomes, iNOS association with the submembranous cortical actin cytoskeleton is ideally suited to deliver NO to microbes in contact with the cell surface and may contribute to early killing of ingested Salmonella.

Increased expression of inducible nitric oxide synthase and cyclo-oxygenase-2 in the airway epithelium of asthmatic subjects and regulation by corticosteroid treatment

BACKGROUND

Nitric oxide (NO) and prostanoids are mediators of vascular and bronchial tone that are postulated to be involved in asthma. Increased levels of both are found in asthmatic subjects and are synthesised by enzymes that have cytokine inducible forms: inducible NO synthase (iNOS) and cyclo-oxygenase-2 (COX-2), respectively. We hypothesised that the in vivo expression of iNOS and COX-2 in the airways would be increased in asthma, and that these cytokine inducible enzymes may represent targets for regulation by corticosteroid treatment.

METHODS

Bronchial biopsy specimens were obtained from three groups of subjects: atopic asthmatics treated with beta(2) agonists alone (n=7), atopic asthmatics additionally receiving regular treatment with corticosteroids (n=8), and non-asthmatic control subjects (n=10). Expression of iNOS and COX-2 mRNA and immunoreactive protein was studied using in situ hybridisation and quantitative immunohistochemistry.

RESULTS

Immunoreactivity and the hybridisation signal for iNOS and COX-2 were mainly localised in the airway epithelium. The proportion of epithelium immunostained was significantly greater in the non-steroid treated asthmatic subjects (iNOS 8.6 (1.8)%; COX-2 26.3 (4.6)%) than either the steroid treated asthmatics (iNOS 3.4 (1.0)%, p=0.009; COX-2 13.0 (0.6)%, p=0.0015) or the non-asthmatic controls (iNOS 4.2 (0.9)%, p=0.018; COX-2 11.6 (0.6)%, p=0.0003). Similarly, the hybridisation signal was stronger in the non-steroid treated group of asthmatic subjects than in the other two groups.

CONCLUSIONS

These findings highlight the potential role of the airway epithelium both as a contributor to the inflammatory process in asthma and as a target for inhaled corticosteroid treatment in this disease.

Effect of adhesion on inducible nitric oxide synthase (iNOS) production in purified human neutrophils

The production of nitric oxide (NO) within neutrophils is an important element of the innate immune response. We have previously shown that cytokines (IL-1alpha, tumour necrosis factor-alpha and interferon-gamma) induce human neutrophils in buffy coat preparations to produce iNOS. In order to define better the exact requirements for iNOS production within human neutrophils, we have studied the conditions needed for the production of iNOS in purified neutrophils. In contrast to buffy coat preparations, purified neutrophils in suspension did not produce an increase in iNOS following addition of cytokines. However, when purified neutrophils were allowed to adhere to glass surfaces either uncoated or coated with fetal calf serum (FCS), plasma, fibronectin or laminin, there was an increase in the percentage of iNOS-positive cells. The addition of cytokines during adhesion of these cells increased this proportion further. This was most marked for glass alone and FCS-coated glass on which the proportion of iNOS-positive cells increased to 22.7% and 35.5%, respectively, a significant increase compared with cytokine-treated neutrophils in suspension. Neither transmigration through activated endothelial monolayers nor the addition of soluble intercellular adhesion molecule-1 to purified neutrophil suspensions increased the percentage of iNOS-positive cells following cytokine stimulation. Adhesion of neutrophils to surfaces coated with IgG or complement also failed to increase cytokine-induced iNOS production. We conclude that iNOS production in human neutrophils requires not only cytokine stimulation, but also additional stimuli from adhesion to a surface.

Bioassay for tumor necrosis factors-alpha and -beta

Tumor necrosis factor (TNF) is a central cytokine in the pathogenesis of septic shock and other inflammatory states. Assay by immunoassay is convenient, but, because of circulating soluble receptors, does not accurately reflect biological activity of the cytokine. This article describes how to perform a bioassay for TNF, using its cytopathic effect on the murine cell line L929. By suitable manipulation, the assay can determine the two different forms of TNF, alpha and beta.

Neutrophils enhance expression of inducible nitric oxide synthase in human normal but not cystic fibrosis bronchial epithelial cells

The bronchial epithelium in cystic fibrosis (CF) expresses very low levels of the inducible form of nitric oxide synthase (iNOS). The product of iNOS, nitric oxide (NO), mediates anti-microbial effects and can reduce neutrophil sequestration in the lung. Heavy neutrophilic infiltration of the pulmonary epithelium is a major feature of the end-stage CF lung. This study hypothesized that the system whereby the pulmonary epithelium protects itself against exaggerated neutrophilic infiltration by producing NO is compromised in CF. Human neutrophils were activated by incubation with cytokines, added to monolayers of normal (16HBE14o-) and CF (CFBE41o-) bronchial epithelial cells and co-cultured for up to 72 h. Marked up-regulation of iNOS protein expression was seen in normal bronchial epithelial cells following neutrophil co-culture but the CF cells showed a significantly smaller increase (p<0.001). To determine whether the relative lack of protein was due to a defect in translation, RT-PCR of iNOS mRNA was carried out and a pattern of mRNA expression was seen paralleling that of the protein. The reduced production of NO by CF compared with normal epithelium was shown by the presence of significantly (p<0.001) less accumulated nitrites in medium after co-culture with neutrophils. In summary, this study shows that the normal production of NO by bronchial epithelium in response to contact with neutrophils is lacking in CF. As NO has been shown to oppose neutrophil sequestration, its relative lack in CF may underlie the heavy neutrophilic infiltration that characterizes the disease.

99Tcm-HMPAO leucocyte labelling in orofacial granulomatosis and gastrointestinal Crohn's disease in childhood and early adulthood

Orofacial granulomatosis is a granulomatous inflammatory disorder, affecting the soft tissues of the face and mouth. The predominant feature is disfiguring lip swelling. Patients with this condition may be exhibiting a Type IV hypersensitivity reaction to dietary or environmental allergens, or these may be the orofacial manifestations of underlying gastrointestinal Crohn's disease. The results of 99Tcm-HMPAO leucocyte labelling of the gastrointestinal tract in 14 patients with orofacial granulomatosis and 15 patients with known gastrointestinal Crohn's disease are presented, indicating that this is a useful and non-invasive screening test for the identification of gastrointestinal Crohn's disease in paediatric and young adult patients presenting with orofacial granulomatosis.

Relationship between the degree of endometrial periglandular fibrosis and the presence of angiotensin-converting enzyme in the equine endometrium

Endometrial periglandular fibrosis (EPF) has been proposed as a possible aetiology for equine embryonic and fetal loss. However, the pathophysiology of EPF is not well understood. Angiotensin-converting enzyme (ACE) is found in macrophages, endothelium (during angiogenesis) and myofibroblasts at sites of fibrosis in the heart, kidneys, liver and skin in several species. An increase in local tissue ACE-binding activity appears to be a critical event in the initiation and progression of fibrosis in these tissues. The aim of this study was to investigate the correlation between ACE activity in the equine endometrium and the degree of EPF, as determined by histological evaluation and morphometry based on a collagen-specific stain. ACE-binding activity values were significantly higher in the endometrial samples with moderate EPF (modified Kenney EPF category IIB) compared with endometria in all other categories. Ultrastructurally, the fibroblasts surrounding the glandular basal laminae in modified Kenney EPF category IIB and III endometria were undergoing myofibroblastic transformation-like changes. These observations indicate a possible link between ACE activity and the onset of EPF in mares.

Inflammatory bowel disease in Scottish children

Most children with inflammatory bowel disease (IBD) require specialist care in a tertiary medical centre. The records of 105 children with IBD who presented to the Royal Hospital for Sick Children, Glasgow between 1976 and 1995 were studied retrospectively. Fifty seven children and Crohn's disease (CD) (median age of presentation 7.9 years) and 48 had ulcerative colitis (UC) (median age of presentation 8.7 years). The number with CD doubled in the decade 1986-95 compared to 1975-85. 23% with CD and 13% with UC developed symptoms before the age of five years. Median time to diagnosis from symptom onset was 45.8 weeks for CD and 12.7 weeks for UC. Histological diagnosis was obtained in all children. The mainstay of treatment was aminosalicylates, and few children underwent surgery (CD 26%, UC 10%). Thirty percent with CD and 23% with UC had no relapses in the study period, and only one child with UC died. Growth was poorly recorded. The majority of children with CD and over 50% with UC had a height-for-age Z score below zero.

13C and H2 breath tests to study extent and site of starch digestion in children with cystic fibrosis

BACKGROUND

Starch is an important source of energy for children with cystic fibrosis, but little is known about their capacity to digest it.

METHODS

A 13C breath test was used to measure starch digestion and oxidation in 16 children with cystic fibrosis (median [range] age, 7.9 [4-15] years; 7 girls, 9 boys) and 5 normal healthy control subjects (median age, 8.3 [7-13] years; 3 girls, 2 boys). A test meal of 13C flour and lactulose was consumed and breath samples were obtained half-hourly thereafter for 6 hours to measure 13C enrichment by isotope ratio mass spectrometry and H2 by electrochemistry. The test was repeated on 10 children with cystic fibrosis when they were taking pancreatic supplements.

RESULTS

The median (range) cumulative percentage 13C dose recovery (cPDR), was 35% (18-52%) in control subjects, 18% (9-33%) in children with cystic fibrosis without enzymes, and 29% (22-51%) in those with pancreatic supplements. cPDR differed significantly between healthy control subjects and children with cystic fibrosis without enzymes (p = 0.01) and between children with cystic fibrosis with and without enzymes (p < 0.0001), but there was no difference between control subjects and children with cystic fibrosis taking enzymes (p = 0.5). Eight children with cystic fibrosis had a cPDR within control range, and in six there was a second peak in 13CO2 enrichment coincident with an increase in H2.

CONCLUSIONS

Starch digestion and oxidation are diminished in children with cystic fibrosis, but pancreatic enzymes restored them to near normal levels. A second peak in 13CO2 enrichment, suggestive of colonic starch fermentation was absent in healthy children, but present in some children with cystic fibrosis and abolished by pancreatic enzymes.

The evolution of liver disease in cystic fibrosis

OBJECTIVES

To describe prospectively the evolution of liver abnormalities in cystic fibrosis (CF), and to assess their impact on nutritional status.

STUDY DESIGN

124 children (61 boys) with CF (median age, 5.4 years; range, 0.1-13.9) were followed longitudinally for a median of four years. Annual clinical examination, biochemistry, and ultrasound assessment were performed. Chrispin-Norman score, anthropometry, and bacterial colonisation of airway secretions were measured at each assessment.

RESULTS

At initial assessment, 45% of the patients had no liver abnormalities, 42% had biochemical abnormality, 35% ultrasound abnormality, and 6% had clinical abnormality of the liver. In this cross sectional analysis, abnormal biochemistry was present in 40% of children with ultrasound or clinical abnormalities, but when longitudinal follow up data were analysed, abnormal biochemistry preceded or coincided with abnormal ultrasound or clinical hepatosplenomegaly in three quarters of 53 children developing new abnormalities. Eighty four of 124 children (68%) showed ultrasound or clinical evidence of liver abnormality at some point during the four years of follow up. No association was found between liver disease and nutritional status.

CONCLUSIONS

Hepatic abnormality was common in this group of children with CF, was often predicted by intermittent biochemical abnormalities, and was not associated with deterioration in nutritional status.

Adequacy of clinical formulae for estimation of energy requirements in children with cystic fibrosis

BACKGROUND

Two clinical formulae (CF conference formula and estimation based on 120% of average requirement for energy) have been recommended for the estimation of energy requirements in cystic fibrosis but their accuracy is unknown.

AIM

To compare the accuracy of estimates of energy requirement derived from the two formulae.

METHODS

Energy requirement, defined as total daily energy expenditure, was measured using the doubly labelled water method in 15 patients (six girls, nine boys; mean (SD) age, 10.0 (2.4) years) who were well and clinically stable. The accuracy of the formulae was assessed using calculation of biases and limits of agreement relative to measured energy requirement.

RESULTS

Estimates from the CF conference formula were lower than measured values (mean paired difference, 0.52 MJ/day; 95% confidence interval (CI), -1.10 to 0. 10), but this bias was not significant, and was smaller than that from the alternative formula (mean paired difference, 0.77 MJ/day; 95% CI, -0.20 to 1.74). Limits of agreement relative to measured total daily energy expenditure were narrower for the CF conference formula (-2.72 to 1.68 MJ/day) than for that based on 120% of estimated average requirement (-2.75 to 4.29 MJ/day), but with both formulae errors in estimation at the individual level were large.

CONCLUSIONS

The CF conference formula offers improved prediction of energy requirements, but the accuracy of both formulae at the individual level is not sufficiently good for clinical purposes.

Energy balance during acute respiratory exacerbations in children with cystic fibrosis

Acute respiratory exacerbations have been proposed to contribute to the negative energy balance which causes undernutrition in cystic fibrosis. However, no studies have measured their effect on all components of energy balance. The aim of this study was to measure the effect of an acute respiratory exacerbation on energy balance. Fourteen children (six females, eight males, mean+/-SD age 9.9+/-2.4 yrs) were studied when well and during the course of an acute respiratory exacerbation treated with intravenous antimicrobial therapy. The total energy expenditure was measured using the doubly-labelled water method, resting energy expenditure by ventilated hood indirect calorimetry, energy intake by household measures records, and fat malabsorption from measurements of dietary fat intake and faecal fat output. The exacerbation was associated with a significant reduction in energy intake (mean paired difference 47 kJ x kg of body weight(-1) x day(-1), p<0.01). Changes in fat malabsorption and resting energy expenditure were negligible. The absence of significant changes in body weight and composition, together with the trend towards lower total energy expenditure, suggested no marked negative energy balance during the exacerbation. In conclusion, treatment of acute respiratory exacerbation with intravenous antimicrobial therapy represents a relatively minor challenge to energy balance and nutritional status in children with cystic fibrosis.

Cyclooxygenase-2 is widely expressed in atherosclerotic lesions affecting native and transplanted human coronary arteries and colocalizes with inducible nitric oxide synthase and nitrotyrosine particularly in macrophages

Inflammation appears to have a major role in the development of atherosclerotic lesions affecting native and transplanted coronary arteries. The subsequent risk of plaque rupture and acute ischemic events correlates with the degree of inflammation and may be modified by aspirin, an anti-inflammatory cyclooxygenase inhibitor. Cyclooxygenase-2 (Cox-2) and inducible nitric oxide synthase (iNOS) are involved in the inflammatory response via the rapid and exaggerated production of prostanoids and nitric oxide, both of which may have proatherosclerotic effects. These effects may be mediated by the formation of peroxynitrite in the case of nitric oxide and involve "cross talk" between the two enzyme systems. This study aimed to investigate native and transplant atherosclerosis for the presence and distribution of Cox-2 and iNOS. Immunocytochemical studies were performed on atherosclerotic lesions from patients with native (n=12) and transplant (n=5) coronary disease by using antibodies to Cox-2, iNOS, and nitrotyrosine (an indicator of peroxynitrite production). Control tissue was obtained from unused donor hearts and at the time of autopsy. Cox-2 and iNOS colocalized predominantly in macrophages/foam cells in both types of atherosclerosis. Cox-2 expression was also detected in medial smooth muscle cells and endothelial cells, including those of the vasa vasorum. Nitrotyrosine was found in the same distribution as that of iNOS and was colocalized with Cox-2 in macrophages. Cox-2 and iNOS are coexpressed in native and transplant atherosclerosis, possibly allowing for interaction between the enzymes and suggesting an alternative mechanism for the benefits of aspirin via inhibition of Cox-2 activity.

Morphometric analysis of endometrial periglandular fibrosis in mares

OBJECTIVES

To develop an objective, quantifiable assay for endometrial periglandular fibrosis (EPF) and correlate assay results with histologic and ultrastructural changes in equine endometrial biopsy specimens.

SAMPLE POPULATION

Endometrial biopsy specimens from 70 mares from 3 to 27 years old in estrus.

PROCEDURE

In a double-blinded study design, endometrial biopsy specimens were graded histologically (modified Kenney classification) for EPF and inflammation. Endometrial periglandular collagen volume fraction (%EPCVF) was determined by light microscopic image analysis of picrosirius red-stained sections. Specimens from selected mares were examined by transmission electron microscopy.

RESULTS

%EPCVF values varied significantly among the 4 modified Kenney EPF categories (I, IIA, IIB, and III) and increased with increasing age of mares. Morphologically, EPF consisted of concentric layers of transformed fibroblasts with myofibroblastic features and deposition of fibrillar collagen around unaltered glandular basal laminae.

CONCLUSIONS AND CLINICAL RELEVANCE

%EPCVF correlates well with morphologic changes in endometrial biopsy specimens. Determination of %EPCVF could be useful in evaluation and clinical management of subfertile mares and in investigations of the pathogenesis of EPF.

Expression of inducible nitric oxide synthase and formation of peroxynitrite in posttransplant obliterative bronchiolitis

BACKGROUND

Obliterative bronchiolitis is characterized histologically by inflammation, epithelial cell damage and loss, fibrosis, and eventual obliteration of airways. Production of high levels of the potential cytotoxin nitric oxide by inducible nitric oxide synthase has been implicated in several inflammatory diseases. The damaging effects of nitric oxide are mediated by peroxynitrite, are formed from nitric oxide and superoxide, and can be demonstrated by the detection of nitrotyrosine. Our previous finding of high inducible nitric oxide synthase expression in inflamed airway epithelium led us to hypothesize that release of nitric oxide in obliterative bronchiolitis mediates the characteristic epithelial damage.

METHODS

Immunocytochemistry was carried out to seek expression of inducible nitric oxide synthase and nitrotyrosine in transplant samples from patients with obliterative bronchiolitis (n=10) and, as controls, unused donor lungs (n=5).

RESULTS

Inducible nitric oxide synthase was strongly expressed in the damaged airway epithelium in obliterative bronchiolitis and in inflammatory cells, where its distribution was matched by that of nitrotyrosine. Normal controls showed little or no immunoreactivity for any of the antigens studied.

CONCLUSIONS

Our findings suggest that nitric oxide may play a role in the pathogenesis of obliterative bronchiolitis and indicate that further work is essential to fully understand the processes and mechanisms involved.

Clinical comparison and performance perspective of three aligning arch wires

OBJECTIVES

To clinically evaluate three commonly used orthodontic tooth aligning arch wires: 016 x 022 inch active martensitic medium force nickel titanium, 016 x 022 inch graded force active martensitic nickel titanium, and 0.0155 inch multistrand stainless steel.

DESIGN

A prospective randomized clinical trial.

DATA SOURCE

Measured serial study casts of dental arches for 112 assigned arch wires from 56 consecutive patients. Analysis based on completed records for 98 arch wires and 51 patients.

METHOD

A consecutive sample of 56 patients requiring both upper and lower fixed appliance therapy were randomly allocated two different arch wires from a possible three under trial. Good quality impressions were taken of the dental arches at the designated serial stages of alignment (start, T0; 4 weeks, T4; 8 weeks, T8). The resultant casts were measured on a Reflex Microscope to record the change in individual tooth alignment both in three and two dimensions (horizontal plane only).

RESULTS

The measurement error was within acceptable limits (range, 0.05 to 0.09 mm) and showed no significant bias. ANOVA statistical models were fitted to the data to adjust for a number of variables. No significant difference in aligning capability (p > 0.05), in either two or three dimensions, was demonstrated between the three arch wires in the trial.

CONCLUSION

Heat activated nickel titanium arch wires failed to demonstrate a better performance than the cheaper multistrand stainless steel wires in this randomized clinical trial. The failure to demonstrate in vivo superiority at the clinical level may be due to the confounding effects of large variations in individual metabolic response. Alternatively, it may be that in routine clinical practice NiTi-type wires are not sufficiently deformed to allow their full superelastic properties to come in to play during initial alignment.