Correction: Emergence of Prions Selectively Resistant to Combination Drug Therapy

[This corrects the article DOI: 10.1371/journal.ppat.1008581.].

Phospholipid cofactor solubilization inhibits formation of native prions

Cofactor molecules are required to generate infectious mammalian prions in vitro. Mouse and hamster prions appear to have different cofactor preferences: Whereas both mouse and hamster prions can use phosphatidylethanolamine (PE) as a prion cofactor, only hamster prions can also use single-stranded RNA as an alternative cofactor. Here, we investigated the effect of detergent solubilization on rodent prion formation in vitro. We discovered that detergents that can solubilize PE (n-octylglucoside, n-octylgalactoside, and CHAPS) inhibit mouse prion formation in serial protein misfolding cyclic amplification (sPMCA) reactions using bank vole brain homogenate substrate, whereas detergents that are unable to solubilize PE (Triton X-100 and IPEGAL) have no effect. For all three PE-solubilizing detergents, inhibition of RML mouse prion formation was only observed above the critical micellar concentration (CMC). Two other mouse prion strains, Me7 and 301C, were also inhibited by the three PE-solubilizing detergents but not by Triton X-100 or IPEGAL. In contrast, none of the detergents inhibited hamster prion formation in parallel sPMCA reactions using the same bank vole brain homogenate substrate. In reconstituted sPMCA reactions using purified substrates, n-octylglucoside inhibited hamster prion formation when immunopurified bank vole PrPC substrate was supplemented with brain phospholipid but not with RNA. Interestingly, phospholipid cofactor solubilization had no effect in sPMCA reactions using bacterially expressed recombinant PrP substrate, indicating that the inhibitory effect of solubilization requires PrPC post-translational modifications. Overall, these in vitro results show that the ability of PE to facilitate the formation of native but not recombinant prions requires phospholipid bilayer integrity, suggesting that membrane structure may play an important role in prion formation in vivo.

Biochemical and structural characterization of two cif-like epoxide hydrolases from Burkholderia cenocepacia

Epoxide hydrolases catalyze the conversion of epoxides to vicinal diols in a range of cellular processes such as signaling, detoxification, and virulence. These enzymes typically utilize a pair of tyrosine residues to orient the substrate epoxide ring in the active site and stabilize the hydrolysis intermediate. A new subclass of epoxide hydrolases that utilize a histidine in place of one of the tyrosines was established with the discovery of the CFTR Inhibitory Factor (Cif) from Pseudomonas aeruginosa. Although the presence of such Cif-like epoxide hydrolases was predicted in other opportunistic pathogens based on sequence analyses, only Cif and its homolog aCif from Acinetobacter nosocomialis have been characterized. Here we report the biochemical and structural characteristics of Cfl1 and Cfl2, two Cif-like epoxide hydrolases from Burkholderia cenocepacia. Cfl1 is able to hydrolyze xenobiotic as well as biological epoxides that might be encountered in the environment or during infection. In contrast, Cfl2 shows very low activity against a diverse set of epoxides. The crystal structures of the two proteins reveal quaternary structures that build on the well-known dimeric assembly of the α/β hydrolase domain, but broaden our understanding of the structural diversity encoded in novel oligomer interfaces. Analysis of the interfaces reveals both similarities and key differences in sequence conservation between the two assemblies, and between the canonical dimer and the novel oligomer interfaces of each assembly. Finally, we discuss the effects of these higher-order assemblies on the intra-monomer flexibility of Cfl1 and Cfl2 and their possible roles in regulating enzymatic activity.

Emergence of prions selectively resistant to combination drug therapy

Prions are unorthodox infectious agents that replicate by templating misfolded conformations of a host-encoded glycoprotein, collectively termed PrPSc. Prion diseases are invariably fatal and currently incurable, but oral drugs that can prolong incubation times in prion-infected mice have been developed. Here, we tested the efficacy of combination therapy with two such drugs, IND24 and Anle138b, in scrapie-infected mice. The results indicate that combination therapy was no more effective than either IND24 or Anle138b monotherapy in prolonging scrapie incubation times. Moreover, combination therapy induced the formation of a new prion strain that is specifically resistant to the combination regimen but susceptible to Anle138b. To our knowledge, this is the first report of a pathogen with specific resistance to combination therapy despite being susceptible to monotherapy. Our findings also suggest that combination therapy may be a less effective strategy for treating prions than conventional pathogens.

Cofactor and glycosylation preferences for in vitro prion conversion are predominantly determined by strain conformation

Prion diseases are caused by the misfolding of a host-encoded glycoprotein, PrPC, into a pathogenic conformer, PrPSc. Infectious prions can exist as different strains, composed of unique conformations of PrPSc that generate strain-specific biological traits, including distinctive patterns of PrPSc accumulation throughout the brain. Prion strains from different animal species display different cofactor and PrPC glycoform preferences to propagate efficiently in vitro, but it is unknown whether these molecular preferences are specified by the amino acid sequence of PrPC substrate or by the conformation of PrPSc seed. To distinguish between these two possibilities, we used bank vole PrPC to propagate both hamster or mouse prions (which have distinct cofactor and glycosylation preferences) with a single, common substrate. We performed reconstituted sPMCA reactions using either (1) phospholipid or RNA cofactor molecules, or (2) di- or un-glycosylated bank vole PrPC substrate. We found that prion strains from either species are capable of propagating efficiently using bank vole PrPC substrates when reactions contained the same PrPC glycoform or cofactor molecule preferred by the PrPSc seed in its host species. Thus, we conclude that it is the conformation of the input PrPSc seed, not the amino acid sequence of the PrPC substrate, that primarily determines species-specific cofactor and glycosylation preferences. These results support the hypothesis that strain-specific patterns of prion neurotropism are generated by selection of differentially distributed cofactors molecules and/or PrPC glycoforms during prion replication.

Full restoration of specific infectivity and strain properties from pure mammalian prion protein

The protein-only hypothesis predicts that infectious mammalian prions are composed solely of PrPSc, a misfolded conformer of the normal prion protein, PrPC. However, protein-only PrPSc preparations lack significant levels of prion infectivity, leading to the alternative hypothesis that cofactor molecules are required to form infectious prions. Here, we show that prions with parental strain properties and full specific infectivity can be restored from protein-only PrPSc in vitro. The restoration reaction is rapid, potent, and requires bank vole PrPC substrate, post-translational modifications, and cofactor molecules. To our knowledge, this represents the first report in which the essential properties of an infectious mammalian prion have been restored from pure PrP without adaptation. These findings provide evidence for a unified hypothesis of prion infectivity in which the global structure of protein-only PrPSc accurately stores latent infectious and strain information, but cofactor molecules control a reversible switch that unmasks biological infectivity.

Inadequate environmental monitoring around offshore oil and gas platforms on the Grand Bank of Eastern Canada: are risks to marine birds known?

Petroleum exploration and production on the Grand Bank of eastern Canada overlaps with productive marine habitat that supports over 40 million marine birds annually. Environmental assessments for oil and gas projects in the region predict insignificant adverse effects on marine birds from oil spills, incineration in platform flares and collisions. Limited baseline data on seasonal occupancies and a failure to quantify the nature and extent of marine bird attraction to platforms and related mortality undermines these assessments. We conducted 22 surveys to offshore platforms on the Grand Bank during 1999-2003 to measure avian associations with platforms and to determine the level of monitoring needed to assess the risks to marine birds. We document seasonal shifts in marine bird occurrences and higher densities of auks (fall) and shearwaters (summer) around platforms relative to surrounding areas. The limited temporal and spatial coverage of our surveys is more robust than existing industry monitoring efforts, yet it is still inadequate to quantify the scale of marine bird associations with platforms or their associated mortality risks. Systematic observations by independent biologists on vessels and platforms are needed to generate reliable assessments of risks to marine birds. Instead, the regulatory body for offshore oil and gas in eastern Canada (Canada - Newfoundland and Labrador Offshore Petroleum Board; C-NLOPB) supports industry self-reporting as the accepted form of environmental monitoring. Conflicting responsibilities of oil and gas regulatory agencies for both energy development and environmental monitoring are major barriers to transparency, unbiased scientific inquiry and adequate environmental protection. Similar conflicts with the oil and gas regulatory body in the United States, the former Minerals and Management Service (MMS) were identified by the U.S. President as a major contributor to the Deepwater Horizon disaster in the Gulf of Mexico. The MMS has since been restructured into the Bureau of Ocean Energy Management, (BOEM) with separate departments responsible for drilling leases and the regulation of drilling activities. Similar restructuring of the oil and gas regulatory bodies in Canada is needed for better public information, scientific investigation and environmental protection in the offshore.

Blood group O and vWf expression may be involved in development of peptic ulcer disease secondary to Helicobacter pylori infection

Helicobacter pylori is a gram negative organism involved in peptic ulcer disease and has been linked to a number of extra-intestinal diseases. There is a large body of evidence describing the link between blood group O/non-secretor phenotypes with H. pylori infection and the risk of peptic ulcer disease. Blood group O individuals also have a higher risk of bleeding disorders due to low levels of the circulating plasma protein von Willebrand factor (vWf). vWf is one of the main proteins that binds platelets during platelet activation and aggregation. The mechanisms of how ulcers develop during H. pylori infection are not fully understood. There is however recent evidence of vWf involvement in platelet aggregation in H. pylori infection. Our new hypothesis states that H. pylori bacteria present in blood group O/non-secretor individuals are binding the available vWf to promote adhesion and subsequent platelet aggregation within the microvasculature. This in turn may deplete any available vWf for wound repair to take place leading to an increased risk of peptic ulceration and bleeding and eventually leading to an ulcer.

Fluticasone induces T cell apoptosis in the bronchial wall of mild to moderate asthmatics

BACKGROUND

Cytokines which signal via the gamma chain of the interleukin (IL)-2 receptor and the interferons (IFNs) have been shown to enhance T cell survival in vitro by rescuing cells from apoptosis.

METHODS

A study was undertaken to determine whether treatment with inhaled fluticasone propionate (FP; 250 microg twice daily) for 2 weeks could modulate production of IL-15 or IFN-beta and thereby affect T cell survival in bronchial tissue of 10 patients with mild/moderate asthma. Bronchial biopsy specimens were taken before and on completion of treatment.

RESULTS

The mean (95% CI) number of T cells per unit area decreased in the asthmatic group following 2 weeks of treatment with FP (from 7.0 (5.6 to 8.4) to 4.5 (4.0 to 5.1); p = 0.001). There was an increase in the percentage of T cells undergoing apoptosis following FP treatment as assessed by T cell/TUNEL staining (from 4.5 (2.6 to 6.4) to 8.7 (6.6 to 10.8); p = 0.0001). The percentage of cells staining for IL-15 and IFN-beta in the lamina propria, determined by an alkaline phosphatase biotin streptavidin technique, decreased significantly from baseline values of 31.6 (23.4 to 39.7) to 19.6 (12.5 to 26.7), p = 0.039 for IL-15 and from 18.9 (13.5 to 24.4) to 9.5 (5.9 to 13.1), p = 0.007 for IFN-beta following 2 weeks of treatment with FP. However, only the decrease in the percentage of cells staining for IL-15 was significantly correlated with an increased number of apoptotic T cells following treatment (p = 0.008).

CONCLUSION

These findings support a novel mechanism for the ability of inhaled corticosteroids to decrease T cell numbers, possibly by downregulation of the cytokine IL-15.

Bed usage in a Dublin teaching hospital: a prospective audit

AIMS AND METHODS

We prospectively audited inpatient bed use in our hospital for the first three months of this year. While 70% (mean age 54 +/- 20.8 years) of our patients went home on the day they were medically discharged, 30% (mean age 70.3 +/- 18.3 years) remained in the hospital awaiting step-down facilities. The total of 486 bed days occupied by overstaying patients would if available, have allowed treatment of 54% more patients without any increase in the hospital complement of beds, preventing the cancellation of elective procedures and preventing patients remaining on trolleys overnight.

RESULTS AND CONCLUSION

These prospective data emphasise (1) a highly inefficient use of acute hospital beds; (2) the need for step-down facilities; (3) efficient use of existing hospital beds is the highest priority both for optimal patient care and optimal use of expensive hospital resources; (4) efficient use of existing facilities should be achieved before the construction of additional facilities.

Release of inflammatory mediators from eosinophils following a hyperosmolar stimulus

Airway dehydration and subsequent hyperosmolarity of periciliary fluid are considered critical events in exercise-induced bronchoconstriction (EIB). It has been shown that an in vitro hyperosmolar stimulation of basophils and mast cells with mannitol can induce the release of histamine and leukotrienes. The aim of this study was to establish if a hyperosmolar challenge could trigger activation of eosinophils to release chemokines and lipid mediators. Peripheral blood eosinophils were isolated from seven asthmatic and six non-asthmatic subjects. Hyperosmolar stimulation of eosinophils with mannitol (0.7 M), resulted in a significant increase in LTC4 levels compared to baseline in both asthmatic (15.2+/-4.6 vs. 70.1+/-9.5; P = 0.0002) and control subjects (14.3+/-4.0 vs. 55.6+/-5.6; P = 0.0001). ECP levels did not increase significantly above baseline following mannitol stimulation in either group. This study shows that eosinophils can be activated by a hyperosmolar stimulus. Therefore it seems reasonable to suggest that eosinophils could contribute to EIB.

A case of frog breathing

Frog breathing (glossopharyngeal breathing) is a useful technique employed to increase ventilation when respiratory muscles are paralysed. It is a technique used by many patients with chronic poliomyelitis, yet many chest physicians and physiotherapists are unfamiliar with this breathing maneuver. Glossopharyngeal breathing coordinates movements of the tongue, cheeks and pharynx to force air from the mouth into the lungs. We report a case of glossopharyngeal breathing, demonstrating a 3 fold increase in vital capacity in a subject with chronic poliomyelitis.

Rapid dendritic cell recruitment to the bronchial mucosa of patients with atopic asthma in response to local allergen challenge

BACKGROUND

Airway dendritic cells (DC) play an important role in chronic allergic airway inflammation in experimental animals, but a similar role for DC in human allergic asthma has been difficult to define. This pilot study was undertaken to elucidate the role of DC in allergic asthma by examining their potential to migrate to the lower airways in response to bronchial challenge with specific allergen.

METHODS

Bronchial biopsy specimens were obtained from seven patients with allergic asthma before and 4-5 hours after allergen challenge. Multicolour immunofluorescence staining was performed on mucosal cryosections to identify changes in the number and phenotypes of DC.

RESULTS

A dramatic increase in the number of CD1c+HLA-DR+ DC were observed in the lamina propria after challenge compared with baseline (22.4 v 7.8 cells/mm(2)). The rapid accumulation (within 4-5 hours) of these cells strongly suggests that they were directly recruited from peripheral blood.

CONCLUSION

We have shown for the first time that a specific DC subset rapidly emigrates into the human bronchial mucosa during allergic inflammation. While this study is based on relatively few patients, the consistency of the overall results strongly suggests that the rapid population dynamics of human airway DC closely parallel those in animal models of acute inflammation. These findings support suggestions that DC have an important role in human airway allergy.

Activated, cytotoxic CD8(+) T lymphocytes contribute to the pathology of asthma death

This study investigates the presence of CD8(+) T lymphocytes and their possible association with viral infection in bronchi of victims of fatal asthma. Postmortem samples from the peribronchial region of the lung were obtained from seven patients who died an asthma death (AD), seven asthmatic patients who died of unrelated causes (AUC), and seven postmortem cases with no history of lung disease (control subjects). Using immunohistochemical techniques, the CD8(+) cytotoxic T-cell population in peribronchial tissue was characterized in three patient groups. The percentage of CD8(+) cells expressing the activation marker CD25 was higher in the AD group than in both the AUC and control groups (11.91 +/- 1.92% versus 3.93 +/- 1.63% and 1.09 +/- 0.56%, respectively (p < 0.001). Perforin expression, a marker of cytotoxicity, was highest in the AD group (9.16 +/- 1.5%) compared with 1.39 +/- 0.9; 1.8 +/- 0.6% in the AUC and control groups respectively (p < 0.001). Expression of interleukin-4 (IL-4) and interferon gamma (IFN-gamma) by CD8(+) T cells was higher in the AD group than the control group (p < 0.05). Furthermore, the IFN-gamma/IL-4 ratio in the AD group was less than half that of the control group (1.46 +/- 0.2 versus 3.2 +/- 0.1; p = 0.02). Using polymerase chain reaction (PCR), viral genome for rhinovirus (RV) was detected in lung tissue from three of the seven cases in the AD group. Two of these cases also had detectable respiratory syncytial virus (RSV). Viral genome for RSV was detected in five of the AUC group and in one of these cases, RV was also detected. No viral genome was detected in the lungs of the control group. In conclusion, this study provides novel evidence of an aberrant CD8(+) T-cell population, possibly in response to viral infection in subjects who die of acute asthma.

Isolation and partial characterisation of immunoglobulin from southern bluefin tuna Thunnus maccoyii Castelnau

Specific and total serum immunoglobulins were extracted by immunoaffinity, mannan-binding protein and Protein A affinity chromatography from southern bluefin tuna (Thunnus maccoyii Castelnau) immunised with rabbit IgG, and from non-immunised southern bluefin tuna. SDS-PAGE in 10% reducing gels revealed two heavy chains with molecular weights of approximately 74.6 +/- 1.3 kDa and 71.2 +/- 0.9 kDa, and two light chains with molecular weights of approximately 29 +/- 1.2 kDa and 28 +/- 1.0 kDa. Under non-reducing, but denaturing, conditions in 4% and 5% SDS-PAGE gels, a high molecular weight and a low molecular weight fraction were demonstrated. By gel filtration using Sephacryl HR 300 a molecular weight of 845 kDa, consistent with a tetramer, was obtained for the high molecular weight fraction, and a molecular weight of 168 kDa, consistent with a monomer, was obtained for the low molecular weight fraction. The extinction coefficient at A280 for the purified immunoglobulin (Ig) was determined to be 1.24. Tuna a-rabbit IgG Ig was reactive with all non-reduced mammalian IgG antigens tested, suggesting that common conformational antigenic determinants were recognised.

Immune responses of teleost fish

In fish all the pre-requisites to mount a specific immune response are present, but the main differences from the mammalian system are that the secondary response is relatively minor and IgG is not present. In teleosts mainly IgM is present, and IgD has been recently described but its function is, as yet, unknown. However, different forms of fish IgM and its observed flexibility of structure may compensate for a lack of Ig class diversity. The innate immune response of teleosts is highly developed. Multiple forms of key constitutive and inducible components, such as lysozyme, C3, alpha2-macroglobulin and C-reactive protein, are present, and may enhance immune recognition. Low ambient temperature appears to have an impact on all aspects of the immune response, particularly the T-dependent specific immune response due to the non-adaptive lipid composition of T-cell membranes. Temperature effects on the nonspecific immune system are less well characterised, but there is evidence that low temperatures are also suppressive. Knowledge of immune system function becomes essential for disease prevention strategies such as the development of vaccines, selection for increased disease resistance and identification of genes suitable for trangenesis.

IFN-gamma but not IL-4 T cells of the asthmatic bronchial wall show increased incidence of apoptosis

BACKGROUND

Previous observations have established that IFN-gamma production is depressed in CD4+ T cells from atopic asthmatics compared with non-asthmatics.

OBJECTIVE

The aim of this study was to determine if decreased IFN-gamma production could be due to a dissociation between levels of apoptosis within the T cell subsets of the asthmatic bronchial wall.

METHODS

Twenty asthmatics (10 atopic and 10 non-atopic) and eight non-atopic non-asthmatics underwent bronchoscopy. Cryostat sections of these biopsies were investigated using immunohistological techniques to determine the relative number of CD4/FAS+ and CD4/Bcl-2+ cells. Detection of IFN-gamma+ and IL-4+ was combined with TUNEL staining to determine the proportions of the Th1 and Th2 cells undergoing apoptosis.

RESULTS

Experiments revealed raised proportions of activated CD4+ T cells as assessed by expression of HLA-DR and CD25+ expression in the asthmatic samples. Expression of Bcl-2 by the CD4+ cell population was significantly reduced in the asthmatic compared with the control group (P = 0.002). There was no significant difference in the expression of CD4+ Fas-ligand or the number of CD4+ undergoing apoptosis in the asthmatic and non-asthmatic groups. However, the IFN-gamma+ (P = 0.04) but not IL-4+ T cells in the asthmatic biopsies had significantly higher proportions of apoptotic cells compared with the control group.

CONCLUSION

The evidence supports the hypothesis that Th1/Th2 imbalance in asthmatic inflammation may be a result of premature apoptosis within the Th1 subset.

The anti-inflammatory profile of inhaled corticosteroids: biopsy studies in asthmatic patients

The beneficial effects of inhaled corticosteroids in the treatment of asthma are well established. A potent topical anti-inflammatory action is assumed to underlie the therapeutic effect, given that these agents alter the number and function of a range of inflammatory cells and markers in airway biopsies. This activity profile is shown by all inhaled corticosteroids, in a variety of patient types and study designs. Thus, treatment with inhaled corticosteroids leads to consistent reductions in the number and activation of mast cells and eosinophils in biopsy specimens. Other relevant findings include reductions in T-lymphocytes, which contribute to chronic inflammation via the secretion of pro-inflammatory cytokines (some of which are responsible for eosinophil accumulation and activation). Inhaled corticosteroids may therefore act by down-regulating immunoreactivity, so reducing activation of T lymphocytes and (consequently) eosinophils. There is considerable interest in whether corticosteroids can inhibit or reverse some structural changes in the airways, including basement membrane thickening, collagen deposition and increased airway vascularity; it has been suggested that these changes may contribute towards airway hyperresponsiveness and irreversible airway obstruction. In summary, inhaled corticosteroids have a broad spectrum of anti-inflammatory activity in asthma patients, but the relationship between changes in clinical and immunopathological parameters, particularly in the long-term, requires further study.

Designing bronchial biopsy studies

Bronchial biopsy provides valuable information about the inflammatory processes in lung tissue, but optimal results are only achieved if the design of intervention studies is sufficiently rigorous. The parallel-group design has merit, but the cross-over design is statistically superior, providing the wash-out period is effective. Heterogeneity of contributing pathologies in asthma patients results in large inter-patient variability which must be controlled for, for example by using strict inclusion criteria, which should ideally relate to the specific inflammatory marker being studied. The inclusion of a placebo group helps to quantify sample variability. The study must have sufficient statistical power to detect inter-group differences for each variable; appropriate adjustments should be made when multiple tests are used. Studies with larger patient numbers are best performed using a multi-centre design, with one centre analysing all tissue samples to reduce variability. Study duration depends on the type of investigation, but should ideally be short. Longer studies are necessary to evaluate chronic changes such as tissue remodelling. Changes in clinical status and cellular events may follow different time courses after intervention. Biopsy measurements are less reproducible than physiological tests, and diurnal variation in the number and function of inflammatory cells can further complicate measurement. The timing of clinical trial assessments needs to allow for these idiosyncrasies. Finally, a balance must be maintained between the risk, albeit small, and the benefit of performing bronchial biopsies.

Fluticasone propionate-induced regulation of the balance within macrophage subpopulations

In asthma, treatment with inhaled corticosteroids reduces chronic peribronchial inflammation and restores the balance within macrophage subpopulations. This study investigates whether corticosteroids can regulate monocyte differentiation in vitro and thereby influence the balance of functionally distinct macrophages. Graded doses of fluticasone propionate (FP) were added to cultures of normal peripheral blood monocytes in the presence or absence of IL-4. Cells were harvested after 7 days' culture. Double immunofluorescence studies were performed on cytospins of differentiated macrophages using the MoAbs RFD1 and RFD7 to distinguish inductive and suppressive macrophages by their respective phenotypes. Macrophage function was determined by quantifying allostimulation in a mixed leucocyte reaction and by measuring tumour necrosis factor-alpha (TNF-alpha) production. FP reduced the number of mature cells with a D1+ antigen-presenting phenotype and up-regulated the development of cells with the D1/D7+ and D7+ phenotypes. Functionally, this was associated with reduced stimulation of T cell proliferation in a mixed leucocyte reaction (MLR). Fluticasone also reversed the increase in both D1+ expression and TNF-alpha production induced by IL-4. The effect of FP persisted for 24 h after removal of FP from the culture medium. These results suggest that FP treatment of asthmatics may have a direct beneficial effect by normalizing the macrophage subset imbalance that contributes to the chronic peribronchial inflammation present in this condition.

The reproducibility of repeat measures of airway inflammation in stable atopic asthma

Measures of airway inflammation are increasingly being used as outcome measures in asthma intervention studies. Meaningful interpretation of observed changes in bronchial mucosal cell numbers should depend, in part, on the reproducibility of repeat measures over time. We wanted to investigate the reproducibility of immunopathologic and physiologic parameters after short and long measurement intervals. We therefore performed spirometry, bronchial provocation challenge, and fiberoptic bronchoscopy with endobronchial biopsy (always right upper lobe second-generation bronchus) at baseline, after 2 wk, and again after 8 wk on nine subjects with stable atopic asthma (receiving inhaled placebo and beta-agonist therapy only). Numbers of T cells, memory T cells (CD45Ro(+)), macrophages (CD68(+)), and eosinophils (EG1(+) and EG2(+)) on immunohistochemical stains of bronchial biopsies were quantified by computerized image analysis. Intraclass correlation coefficients (ICCs) of reproducibility were calculated for repeat measures of each parameter and a high ICC (greater than 0.6) was interpreted as "highly reproducible." Repeat measures of FEV(1), FEF(25-75%), and PC(20) were highly reproducible after short (2-wk) and long (8-wk) intervals. Only repeat measures of EG2(+) had an ICC greater than 0.6 after 8 wk. Repeat measures of CD45Ro(+), EG2(+), and T cell numbers (but not CD68(+) and EG1(+) cells) are highly reproducible and reliable parameters of asthmatic airway inflammation after a 2 wk interval.

A comparison of the efficacy of long-acting beta 2-agonists: eformoterol via Turbohaler and salmeterol via pressurized metered dose inhaler or Accuhaler, in mild to moderate asthmatics. Force Research Group

Four hundred and sixty nine patients were randomized to receive either 12 micrograms bd of eformoterol (Oxis, Astra Pharmaceuticals Ltd., Kings Langley, U.K.) delivered via Turbohaler or 50 micrograms bd salmeterol (Serevent, Glaxo-Wellcome Ltd., Uxbridge, U.K.) via either the Accuhaler (Glaxo-Wellcome Ltd.) or pressurized metered dose inhaler (pMDI, Glaxo-Wellcome Ltd.) for 8 weeks. This was followed by a 4-week cross-over period when patients who had received salmeterol in the previous 8 weeks were given eformoterol and patients who had received eformoterol were given either salmeterol via the Accuhaler or pMDI to assess patient device and treatment preference. For the primary efficacy variable, the increase in peak expiratory flow (PEF) rate from run-in to 8 weeks, similar significant improvements were seen in all three treatment groups. Eformoterol Turbohaler (FT) achieved a greater increase in morning PEF than salmeterol Accuhaler (SA) from randomisation to 4 weeks; the increase shown in the eformoterol Turbohaler group was 28.9 1 min-1 compared to 19.91 min-1 for the salmeterol Accuhaler group. The addition of eformoterol Turbohaler 12 micrograms bd, to patients' existing asthma therapy was found to have a significantly more beneficial effect on the severity of patients' daytime asthma symptoms than had salmeterol Accuhaler 50 micrograms bd (P = 0.014). Eformoterol Turbohaler reduced the severity of daytime asthma symptoms by 42% after only 4 weeks of treatment. The patients in the eformoterol Turbohaler treated group experienced a higher percentage of days when they were symptom-free and did not use their short-acting bronchodilator to relieve symptoms (32.8, 24.1 and 28.0% in the FT, SA and SM groups, respectively). At 8 weeks there were no significant differences in any of these variables between the three groups. Patients in all the treatment groups gained an additional 1-1.5 nights undisturbed by asthma per week. The changes in sleep disturbance were not significantly different between the three treatment groups. In addition to the therapeutic benefits provided by eformoterol Turbohaler the device (Turbohaler) was the significant preference of patients given both Turbohaler and pMDI (P = 0.0168) and was also considered to be significantly more convenient to carry around than the Accuhaler (P < 0.0001). No other differences were found between the three devices. The results of this study demonstrate that the addition of a long-acting beta 2-agonist is an effective tool for achieving the goals of asthma treatment. Eformoterol via the Turbohaler is at least as effective as salmeterol via either the Accuhaler or the pMDI in achieving these goals.

A comparison of the efficacy of long-acting beta 2-agonists: eformoterol via Turbohaler and salmeterol via pressurized metered dose inhaler or Accuhaler, in mild to moderate asthmatics. Force Research Group

Four hundred and sixty nine patients were randomized to receive either 12 micrograms bd of eformoterol (Oxis, Astra Pharmaceuticals Ltd., Kings Langley, U.K.) delivered via Turbohaler or 50 micrograms bd salmeterol (Serevent, Glaxo-Wellcome Ltd., Uxbridge, U.K.) via either the Accuhaler (Glaxo-Wellcome Ltd.) or pressurized metered dose inhaler (pMDI, Glaxo-Wellcome Ltd.) for 8 weeks. This was followed by a 4-week cross-over period when patients who had received salmeterol in the previous 8 weeks were given eformoterol and patients who had received eformoterol were given either salmeterol via the Accuhaler or pMDI to assess patient device and treatment preference. For the primary efficacy variable, the increase in peak expiratory flow (PEF) rate from run-in to 8 weeks, similar significant improvements were seen in all three treatment groups. Eformoterol Turbohaler (FT) achieved a greater increase in morning PEF than salmeterol Accuhaler (SA) from randomisation to 4 weeks; the increase shown in the eformoterol Turbohaler group was 28.9 l min-1 compared to 19.9 l min-1 for the salmeterol Accuhaler group. The addition of eformoterol Turbohaler 12 micrograms bd, to patients' existing asthma therapy was found to have a significantly more beneficial effect on the severity of patients' daytime asthma symptoms than had salmeterol Accuhaler 50 micrograms bd (P = 0.014). Eformoterol Turbohaler reduced the severity of daytime asthma symptoms by 42% after only 4 weeks of treatment. The patients in the eformoterol Turbohaler treated group experienced a higher percentage of days when they were symptom-free and did not use their short-acting bronchodilator to relieve symptoms (32.8, 24.1 and 28.0% in the FT, SA and SM groups, respectively). At 8 weeks there were no significant differences in any of these variables between the three groups. Patients in all the treatment groups gained an additional 1-1.5 nights undisturbed by asthma per week. The changes in sleep disturbance were not significantly different between the three treatment groups. In addition to the therapeutic benefits provided by eformoterol Turbohaler the device (Turbohaler) was the significant preference of patients given both Turbohaler and pMDI (P = 0.0168) and was also considered to be significantly more convenient to carry around than the Accuhaler (P < 0.0001). No other differences were found between the three devices. The results of this study demonstrate that the addition of a long-acting B2-agonist is an effective tool for achieving the goals of asthma treatment. Eformoterol via the Turbohaler is at least as effective as salmeterol via either the Accuhaler or the pMDI in achieving these goals.

Fluticasone propionate induced alterations to lung function and the immunopathology of asthma over time

BACKGROUND

Inhaled corticosteroids are the most widely used treatment for asthma, a disease characterised by both functional and immunopathological abnormalities. This study investigated the relative effects of inhaled corticosteroids on these two features of asthma over time.

METHODS

A randomised, double blind, placebo controlled, parallel group study with inhaled fluticasone propionate, (FP 2 mg daily) was conducted in 27 patients with asthma. Following baseline analysis, the study tested the effects of short term (two weeks) and longer term (eight weeks) treatment. At each time point (0, 2, and 8 weeks) lung function tests were performed and endobronchial biopsy specimens obtained to determine the distribution and number of lymphocyte, macrophage and eosinophil subsets using immunohistological analysis. Twenty three patients completed the study, 11 on FP and 12 placebo.

RESULTS

FEV1, delta FEV1, FEF25-75, and FEV1/FVC all improved after two weeks of FP treatment. This improvement was maintained but not increased after eight weeks. PC20FEV1 showed a trend to increase but was not significantly improved at eight weeks. No significant changes were seen in the placebo group. The numbers of T cells, macrophages, and eosinophils in the bronchial wall were reduced by two weeks of treatment with FP but were unaltered by placebo. The improvement offered by FP continued over the eight week period. Reductions in CD4:CD8 ratio and numbers of activated (EG2+) eosinophils were only significant after eight weeks of treatment.

CONCLUSIONS

These results reveal that FP influences both functional and immunopathological parameters of asthma. Temporal relationships suggest that these are parallel but not necessarily interrelated effects. While short term treatment is effective in "normalising" the functional abnormalities in asthma, the impact of FP on bronchial inflammation appears to be progressive, taking up to eight weeks and more.

Dysregulation of monocyte differentiation in asthmatic subjects is reversed by IL-10

BACKGROUND

IL-10 can modulate the differentiation of normal monocytes to macrophages, increasing the proportion of maturing cells with a phenotype consistent with T cell suppressive activity. Analysis of the immunopathology in endobronchial biopsies from asthmatic subjects has revealed significantly reduced proportions of suppressive macrophage populations associated with chronic T-cell mediated inflammation.

OBJECTIVE

This study investigates whether the altered homeostasis within the lung macrophage populations in asthma is reflected in aberrant differentiation of peripheral blood monocytes and whether this differentiation may be influenced by IL-10.

METHODS

Monocytes from 14 normal individuals and 14 atopic asthmatics were grown in culture for 7 days in the presence or absence of IL-10, added on day 5. Double immunofluoresence studies were performed on cytospins of the differentiated macrophages using the monoclonal antibodies RFD1 and RFD7 to distinguish inductive and suppressive macrophages by their respective phenotypes. HLADR expression was quantified using the monoclonal antibody RFDR1. Macrophage function was determined by quantifying allostimulation in a mixed leucocyte reaction and by measuring TNFalpha and TGFbeta production.

RESULTS

With no cytokine addition the proportion of maturing macrophages with a suppressive phenotype (D1+D7+) at day 7 was lower in the asthmatic samples (18%) compared with normals (25%). IL-10 increased the proportion of suppressive cells in cultures of both asthmatic and normal monocytes with the increase in the asthmatic subjects (94% increase) being significantly greater than that in normal subjects (32% increase) (P<0.01). Asthmatic monocytes had a greater effect in stimulating MLR than normals (P < 0.05) but the addition of IL-10 reduced T cell proliferation in an MLR to a equivalent level in both groups.

CONCLUSIONS

These results suggest that a fundamental problem may exist in the differentiation of monocytes in asthma which may be reversed by IL-10.

Bronchoscopic diagnosis of sarcoidosis

Transbronchial lung biopsy (TBLB), transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and bronchoalveolar lavage (BAL) are routinely performed at fibreoptic bronchoscopy. Up to the present time, no data have been available on the efficacy of performing all three of these procedures simultaneously in the bronchoscopic work-up of sarcoidosis. A prospective study was undertaken to compare the diagnostic yield from TBLB, TBNA and BAL in patients presenting with clinical and radiological features typical of sarcoidosis. Thirteen consecutive patients with clinical and radiological features consistent with stage I and II sarcoidosis underwent bronchoscopy with TBLB, TBNA and BAL. Noncaseating granulomata (stain and culture negative for tuberculosis bacilli and fungi) were found in seven of the 13 patients by TBLB, and in six of the 13 patients by TBNA (of which four patients had negative TBLB). Eight of the 13 patients had classical "sarcoid" BAL findings, i.e. >12% lymphocytes, and high CD4+:CD8+ lymphocyte ratio. Combining TBLB, TBNA and BAL gave a diagnostic sensitivity of 100% (12 out of 12 patients) for sarcoidosis. The remaining patient had nondiagnostic bronchoscopic studies and mediastinoscopy biopsy showed a non-Hodgkin's lymphoma. Our data suggest that performing simultaneous transbronchial lung biopsy, transbronchial needle aspiration and bronchoalveolar lavage produces optimal results in the diagnosis of sarcoidosis.

A comparison of regular with intermittent bronchodilators in asthma patients on inhaled steroids

The aim of this study was to compare the effect of regular versus intermittent (p.r.n.) bronchodilators on bronchial reactivity and asthma control in patients on concomitant inhaled corticosteroids. We studied 12 patients with asthma in a prospective, randomised, single-blind, single-dummy, three-period crossover trial comparing placebo (2 puffs t.d.s.), salbutamol (200 micrograms t.d.s.) and oxitropium bromide (200 micrograms t.d.s.) for 28 days each. Computerised spirometry and bronchial reactivity to histamine were obtained on entry and after each treatment period. Symptom scores, use of rescue bronchodilator and peak expiratory flow rates were recorded daily. There were no significant differences in bronchial hyperreactivity between the salbutamol, oxitropium and placebo treatment periods. There were no significant differences in baseline FEV1, FEF25-75%, symptom scores, use of rescue bronchodilator or morning and evening PEFR between treatment periods. Intermittent beta agonist therapy is as effective as regular therapy in terms of asthma control and bronchial hyperreactivity in patients on concomitant inhaled corticosteroid therapy. Since intermittent therapy achieves similar results with significantly lower beta agonist consumption, the data support current recommendations that beta agonists should be taken on a p.r.n. basis in asthma patients on inhaled steroids.

Allergen-induced CD30 expression on T cells of atopic asthmatics

BACKGROUND

The importance of TH2-type T cell cytokines in atopic disease is widely accepted. CD30, a member of the TNF/NGF receptor superfamily, is expressed on a proportion of activated CD45RO+ T cells and has been proposed as a marker for TH2 phenotype. CD30 ligand-CD30 interaction has been shown to positively influence development of the TH2 phenotype, and serum levels of soluble CD30 (sCD30) have been used as prognostic markers in HIV, SLE, Epstein-Barr Virus infection and Hodgkin's Lymphoma but not as yet in allergic disease.

OBJECTIVES

To establish if serum levels of sCD30 are elevated in atopic asthma and determine whether allergen-induced proliferation/activation of PBMCs from atopic asthmatics promotes CD30 expression on CD4+ T lymphocytes. Further, to determine if expression of CD30 and sCD30 correlate with disease severity.

METHODS

Eighteen atopic asthmatics were each assigned a symptomatic disease score based on symptoms and bronchodilator rescue usage. Serum sCD30 was measured in peripheral blood by ELISA. PBMCs from atopic asthmatics were analysed with flow cytometry to obtain the proportions of CD4+ T cells expressing CD45RO and CD30. The cells were then cultured for 10 days with IL-2 with or without house dust mite antigen. A proliferation index was recorded and expression of CD30 and CD45RO retested. As a control, stimulation with PHA was used. Results with patients' PBMCs were compared with results of a parallel analysis of PBMCs from non-atopic healthy controls.

RESULTS

Serum sCD30 was elevated in the 18 atopic asthmatics compared with a group of normal subjects but levels did not correlate with symptomatic disease activity. CD4CD45RO expression was low (14%) in atopic asthmatic peripheral blood but increased to 41% after 10 days culture with allergen. The CD4:CD8 ratio increased after Der p stimulation. A significant rise in the percentage of CD4+ T cells expressing surface CD30 (29%) was seen along with increased mean fluorescence intensity. Both these results correlated with symptomatic disease severity score. Non-specific PHA stimulation failed to significantly affect CD30 expression.

CONCLUSIONS

There is a specific response to allergen in atopic asthma which causes significant increases in CD30 expression. This may correlate with disease severity.

"Golf ball liver": agent orange hepatitis

2,4-Dichlorophenoxyacetic acid (2,4-D) is a selective weedkiller which works by uncoupling oxidative phosphorylation and is in widespread use. It is known as "agent orange". A 65 year old man had acute hepatitis, thought to be caused by exposure to 2,4-D. The patient ingested 2,4-D as a result of habitual licking of his golf ball. Clinical and histological data together with a challenge test confirmed the diagnosis of "golf ball liver".

T-cell cytokines may control the balance of functionally distinct macrophage populations

As monocytes differentiate into mature macrophages, subsets emerge that exhibit stimulatory, suppressive or phagocytic potential. These functionally distinct subsets can be discriminated using monoclonal antibodies RFD1 and RFD7. As examples of all these subsets have been repeatedly identified within the macrophage pool in a variety of organs the overall functional capacity of this pool will depend on the relative balance of these subpopulations. This study investigates whether this balance present in mature macrophage populations can be regulated by the local influence of T-cell-derived cytokines. The dose-dependent effect of cytokines interferon-gamma (IFN-gamma), interleukins (IL) IL-2, IL-4 and IL-10 on the phenotype and function of monocyte-derived macrophages was determined. Subsets of mature cells were quantified by identifying RFD1- RFD7- stimulatory cells (D1+); RFD1- RFD7+ phagocytes (D7+) and RFD1+ RFD7+ suppressive cells (D1 D7+). IFN-gamma and IL-4 increased the relative proportions of D1+ stimulatory cells and upregulated HLA-DR expression. IFN-gamma also increased the capacity of the mature macrophage pool to stimulate T-cell proliferation. IL-10 reduced the proportions of D1+ stimulatory cells while promoting the differentiation of D7+ phagocytes and D1/D7+ suppressive cells. IL-10 induced changes also reduced the functional capacity of the mature populations to stimulate T cells in auto and allogenic mixed lymphocyte reactions (MLR). IL-2 had no effect on differentiation of monocytes. Thus IL-4 and IFN-gamma are seen to induce the development of stimulatory macrophages while IL-10 promotes differentiation of monocytes to mature phagocytes and suppressive macrophages. It is concluded that mature macrophage phenotype is 'plastic' and under the control of T-cell-derived mediators. Furthermore, within the differentiating monocytes, phenotypic change appears to carry with it functional change, thus retaining the relationship between antigen expression and activity in the mature macrophage populations.

Lung immunopathology in cases of sudden asthma death

The histopathology of airway inflammation in rare cases of sudden asphyxic asthma death (SAAD) is unclear. This study examines, for the first time, the relative disposition of lymphocyte and macrophage subsets and eosinophils in proximal and distal tissues of such cases. Multiple resection specimens from five cases of SAAD were studied. Tissue blocks were obtained at necroscopy and immediately frozen in liquid nitrogen within 18 hours of death (death occurring within 1 h of the onset of an unprovoked asphyxic asthma attack). After immunohistological staining, frozen sections underwent semi-quantitative analysis (cell counts per unit area) for T-cells, macrophages and eosinophils using computerized imaging systems. Subsets of T-cells and macrophages were estimated using double immunofluorescence techniques. Variability within samples, between samples and between cases was compared. These cases of fatal asthma showed infiltrates of T-cells, macrophages and eosinophils within peribronchial tissues. Distinct from stable asthma, a CD8+ T-cell dominance was found. A high proportion of eosinophils were activated (EG2+), whereas the relative proportion of antigen-presenting cells (RFD1+) did not seem to be abnormal, although numbers of these cells were high. These features were seen both in proximal and distal tissues. The variability of these parameters within an individual was 9.4-15.2%, however, the variability between individual cases was greater. Sudden asphyxic asthma is associated with inflammatory infiltrates both of proximal and distal lung tissues. In contrast to stable asthma, this infiltrate contains large numbers of CD8+ T-cells, suggesting distinct qualitative as well as quantitative characteristics in the immunopathology of sudden asthma death.

Utility of Wang transbronchial needle biopsy in sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown aetiology, commonly seen in the western world. The incidence varies and may be as high as 40/100,000 of the population per year. The commonest mode of presentation is as hilar and mediastinal lymphadenopathy on a chest radiograph. Even though sarcoid is in general a benign disease and most patients will not progress to chronic lung disease, a tissue diagnosis is necessary for management as other differential diagnoses such as lymphoma, tuberculosis and other causes of interstitial lung disease need to be excluded. The usual method of obtaining a tissue diagnosis is transbronchial forceps biopsy (TBBx), via a fibre-optic bronchoscope (FOB). The presence of non-caseating granuloma in the biopsy specimen is diagnostic of sarcoidosis if the tissue is stain and culture negative for tuberculosis and fungi. However TBBx carries significant complications-in particular there is a risk of pneumothorax (10-20 per cent) and significant and rarely life-threatening haemorrhage has been reported. Furthermore, a diagnosis of sarcoidosis is made by TBBx in only approximately 70 per cent of cases. Thus in about 30 per cent of cases a further procedure such as mediastinoscopy or open lung biopsy is required to obtain a tissue diagnosis. We report a patient with suspected sarcoidosis who had negative TBBx in whom the diagnosis was confirmed using a Wang transbronchial needle (MW-319, Mill Rose Lab., U.S.A.) to biopsy mediastinal lymph nodes via the FOB.

Relative effects of inhaled corticosteroids on immunopathology and physiology in asthma: a controlled study

BACKGROUND

Although corticosteroids are recognised as the most efficacious treatment for bronchial asthma, their mode of action remains unclear. A placebo controlled trial was undertaken of the effect of inhaled corticosteroids on physiological and immmunopathological parameters in asthmatic patients in whom the correlations between these indices were tested after treatment.

METHODS

Sixteen patients (two women) with asthma entered a double blind, placebo controlled, parallel study during which they inhaled either budesonide 800 micrograms twice daily or matching placebo for six weeks. Spirometric parameters and bronchial reactivity to histamine and terbutaline were measured and endobronchial biopsy samples were taken before and after treatment. Patients recorded morning and evening flow rates during the treatment period. The biopsy samples were subjected to immunohistological analysis to determine the disposition of inflammatory cells within the bronchial wall.

RESULTS

Treatment with budesonide resulted in a significant improvement in the 25-75% forced expiratory flow (FEF25-75) from a mean of 133 l/min before treatment to 169 l/min after treatment, and in the morning peak expiratory flow rate (PEFR) from a mean of 384 l/min before treatment to 415 l/min after treatment. No changes were seen in the placebo group. Comparison between the changes in the immunopathological indices after six weeks of treatment with placebo or budesonide showed a significant reduction in the numbers of mast cells (0.5/unit area to 0.2/ unit area), activated eosinophils, and the expression of HLA-DR antigens (relative density -1.9 before to 1.02 after treatment) on inflammatory cells in response to treatment with budesonide. Although reductions in the numbers of other inflammatory cells within the bronchial wall were recorded using immunohistological analysis, these changes were not statistically significant. Significant correlations were found between changing immunological indices and lung physiology.

CONCLUSIONS

This controlled study shows that inhaled corticosteroids cause improvement in physiological and immunopathological parameters in patients with stable asthma that are not seen with placebo, and that cause and effect relationships may exist between these two measures of disease status.

Macrophages and allergic lung disease

Allergic lung diseases such as atopic asthma and extrinsic allergic alveolitis are now recognized as chronic inflammatory lung diseases promoted by dysregulation of T cell-mediated immune mechanisms. The basis of this regulation and the impact of the atopic status of these individuals on this chronic inflammatory disease have yet to be fully explained. The studies described in this paper reveal mechanisms of macrophage lymphocyte interaction in which evidence is presented that a balance of functionally distinct macrophage subsets needs to be maintained to regulate T cell reactivity in the lung. Similarly a balance within the T cell populations may influence and regulate the relative proportions of functionally distinct macrophages. Investigations of bronchoalveolar lavage and biopsy from patients with allergic lung disease have revealed a gross imbalance within the lung macrophage populations and an associated dysregulation in T cell stimulation. In vitro studies have revealed that imbalances in the macrophage populations may lead to changes in local level of cytokine production specifically TGF-beta which would then impact on the control of T cell populations. Conversely aberrant development of activated T cells with a TH2-like cytokine repertoire may influence the balance of macrophages. Our in vitro studies have revealed that macrophage phenotype and function can be modulated in vitro by contact with T cell-derived cytokines and that this change in phenotype is reflected in a change in function. These data support the hypothesis that components of the immune system normally associated with allergic reactions may be stimulated in the absence of any overt atopic reactivity in the individual concerned. Thus immediate type allergic reactions may represent a "super-imposed" burden [provocating factor] in atopic individuals but the underlying immunopathogenesis of these diseases may not be dependent on this state of immediate type hypersensitivity. It is concluded that the loss of balance within functional distinct macrophage populations within the lung may represent the fundamental problem in allergic lung disease. This possibility is discussed in the light of other work in this field.

Benthic microbial production of oxygen supersaturates the bottom water of a stratified hypersaline lake

Lake Hayward is a hypersaline lake that stratifies seasonally and maintains oxygen supersaturation in its bottom water for about 6 months each year. This phenomenon was found to be the result of photosynthesis by the benthic microbial communities, composed primarily of the cyanobacteria Cyanothece spp., Spirulina sp., and Oscillatoria sp. When these communities were present and the lake was stratified, the bottom water was supersaturated with oxygen (up to 370%). During illumination, the benthic microbial communities rapidly developed very high concentrations (e.g., >500 μM) of oxygen, which then diffused into the overlying water. However, while the overlying water became supersaturated, the concentration in the water was lower than in the benthic microbial communities because (1) transport across the sediment-water interface was limited by diffusion, and (2) turbulence rapidly mixed the oxygen throughout the much larger volume of the bottom water (approximately 1.5 m deep). Thus, import of oxygen by the benthic microbial communities at night proceeded more slowly than daytime export, allowing supersaturation of the bottom water to develop.

T-cell and macrophage subsets in the bronchial wall of clinically healthy subjects

This study was conducted to obtain quantitative data on the numbers of T-cells and macrophage subsets in the normal bronchial wall of man, and, thus, produce a baseline against which the numbers of these cells present in inflamed bronchi may be judged. Bronchial biopsies were obtained from 27 clinically healthy subjects attending hospital for elective orthopaedic operations. Eight of the subjects were smokers (median 3.5 pack-years), and eight were atopic as defined by skin prick test. Three to eight weeks after biopsy, subjects attended the lung function laboratory for spirometric testing and determination of provocative concentration of histamine producing a 20% fall in forced expiratory volume in one second (PC20FEV1). The bronchial biopsies were frozen and cryostat sections prepared. These sections were investigated with immunohistological techniques to reveal the presence and distribution of T-cell and macrophage subsets. Twenty six out of 27 subjects had spirometric values within the normal range, but a wide spectrum of bronchial reactivity was observed (PC20FEV1 range 2-36 mg histamine). Using monoclonal antibodies in immunohistological techniques, only small numbers of T-cells were seen, the majority being CD8+ cells in the epithelium. In the underlying tissue, CD4+ cells predominated (CD4/CD8 ratio, epithelium 1:9; underlying tissue 4:1). In both cases, approx. 50% of T-cells expressed the CD45Ro isotype. Small numbers of macrophages were observed in all samples. The majority of these cells expressed a "suppressor cell" phenotype (RFD1+RFD7+), whilst only a small proportion (median 11% ) exhibited the phenotype of antigen presenting cells (RFD1+RFD7-).(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative evaluation of propofol and midazolam as sedative agents in fiberoptic bronchoscopy

Propofol, a new intravenous sedative agent, was investigated in 41 asthmatic patients undergoing day-case (outpatient) fiberoptic bronchoscopy. The study design was a randomized comparison between propofol and midazolam, which is a well-established intravenous sedative agent. The age, weight, and American Society of Anesthesiologists physical status and lung function of the two groups were not significantly different. Mean (SD) induction dose of propofol was 104.7 (30.1) mg with a maintenance dose of 121.9 (38.5) mg. Corresponding values of midazolam were 9.3 (3.1) mg and 3.7 (2.3) mg. The required level of sedation was achieved significantly faster with propofol, mean (SD) 125.4 (39.8) s, compared with midazolam, 179.4 (55.2) s (p < 0.001). Significantly faster recovery was noted with propofol compared with midazolam in terms of time to recall name and date of birth 2.3 (1.7) min vs 6.3 (8.6) min, (p < 0.045). Alertness scored with the digital symbol substitution test (DSST) returned to prebronchoscopy values in the propofol group at 30 min, DSST score = 35.9 (18.2) vs 13.4 (9.1), in the midazolam group (p < .0001) and was still significantly higher at 90 min-39.4 (17.9) and 23.1 (13.8) (p < 0.01). We conclude that propofol is a useful sedating agent in fiberoptic bronchoscopy with similar efficacy to midazolam but with a faster onset of action and a more rapid recovery. These represent significant advantages for day-case procedures.

Resting metabolic rate and postprandial thermogenesis by level of aerobic fitness in young women

Resting metabolic rate (RMR) and the thermic effect of a meal (TEM) were compared among women of three levels of aerobic fitness. Twenty-three euthyroid, eumenorrheic women (aged 18-35 years) were divided into three groups based on VO2 max standardized for fat-free weight (FFW), as determined from a graded exercise test: High Fit (HF): n = 7, VO2 max > 70 ml*kg FFW-1*min-1; Moderately Fit (MF): n = 8, VO2 max = 55-70 ml*kg FFW-1*min-1; and Low Fit (LF): n = 8, VO2 max < 55 ml*kg FFW-1*min-1). At 0700h RMR was measured for 1 h by indirect calorimetry with subjects in a fasted, preovulatory state, having refrained from exercise on the preceding day. The subject then consumed a liquid meal (12 kcal*kg FFW-1) and indirect calorimetry was continued for 3 h to determine the TEM. RMR adjusted for FFW using analysis of covariance was significantly higher (P < 0.05) in the HF group (mean +/- SEM = 1.08 +/- 0.03 kcal*min-1) compared to the MF (0.99 +/- 0.04) and LF (0.90 +/- 0.04) groups. Group differences in the thermic response did not reach statistical significance, although there was a trend for a high TEM in the HF group. There was a positive relationship between RMR and energy flux (average daily kcalorie intake + daily kcaloric expenditure in physical activity). These results suggest that women who exhibit high levels of exercise and aerobic fitness may be less energy efficient during the non-exercise portion of the day then their less active counterparts.