A mitochondrial surveillance mechanism activated by SRSF2 mutations in hematologic malignancies

Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.

A mitochondrial surveillance mechanism activated by SRSF2 mutations in hematologic malignancies

Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.

A Phase I Trial of Sirolimus with "7&3" Induction Chemotherapy in Patients with Newly Diagnosed Acute Myeloid Leukemia

Chemotherapy remains a primary treatment for younger AML patients, though many relapse. Data from our group have shown that highly phosphorylated S6 in blasts may predict response to sirolimus given with chemotherapy. We report the results of a phase I study of this combination in newly diagnosed AML and the pharmacodynamic analysis of pS6 before and after treatment. Subjects received sirolimus (12 mg on day 1, 4 mg daily, days 2-10), then idarubicin and cytarabine (days 4-10). Response was assessed at hematologic recovery or by day 42 using a modified IWG criteria. Fifty-five patients received sirolimus. Toxicity was similar to published 7 + 3 data, and 53% had high-, 27% intermediate-, and 20% favorable-risk disease. Forty-four percent of the high-risk patients entered into CR/CRp. Seventy-nine percent of the intermediate-risk subjects had a CR/CRp. All favorable-risk patients had a CR by day 42; 9/11 remained alive and in remission with a median follow-up of 660 days. Additionally, 41/55 patients had adequate samples for pharmacodynamic analysis. All patients demonstrated activation of S6 prior to therapy, in contrast to 67% seen in previous studies of relapsed AML. mTORC1 inhibition was observed in 66% of patients without enrichment among patients who achieved remission. We conclude that sirolimus and 7 + 3 is a well-tolerated and safe regimen. mTORC1 appears to be activated in almost all patients at diagnosis of AML. Inhibition of mTORC1 did not differ based on response, suggesting that AML cells may have redundant signaling pathways that regulate chemosensitivity in the presence of mTORC1 inhibition.

LNS8801 inhibits Acute Myeloid Leukemia by Inducing the Production of Reactive Oxygen Species and Activating the Endoplasmic Reticulum Stress Pathway

Despite recent therapeutic advances, the 5-year survival rate for adults with acute myeloid leukemia (AML) is poor and standard-of-care chemotherapy is associated with significant toxicity, highlighting the need for new therapeutic approaches. Recent work from our group and others established that the G protein-coupled estrogen receptor (GPER) is tumor suppressive in melanoma and other solid tumors. We performed a preliminary screen of human cancer cell lines from multiple malignancies and found that LNS8801, a synthetic pharmacologic agonist of GPER currently in early phase clinical trials, promoted apoptosis in human AML cells. Using human AML cell lines and primary cells, we show that LNS8801 inhibits human AML in preclinical in vitro models, while not affecting normal mononuclear cells. Although GPER is broadly expressed in normal and malignant myeloid cells, this cancer-specific LNS8801-induced inhibition appeared to be independent of GPER signaling. LNS8801 induced AML cell death primarily through a caspase-dependent apoptosis pathway. This was independent of secreted classical death receptor ligands, and instead required induction of reactive oxygen species (ROS) and activation of endoplasmic reticulum (ER) stress response pathways including IRE1α. These studies demonstrate a novel activity of LNS8801 in AML cells and show that targeting ER stress with LNS8801 may be a useful therapeutic approach for AML.

Significance

Previous work demonstrated that LNS8801 inhibits cancer via GPER activation, especially in solid tumors. Here we show that LNS8801 inhibits AML via GPER-independent mechanisms that include ROS induction and ER activation.

Real-world effectiveness of intensive chemotherapy with 7&3 versus venetoclax and hypomethylating agent in acute myeloid leukemia

Intensive chemotherapy with cytarabine and anthracycline (7&3) remains the standard therapy for patients medically fit for induction, but the assessment of fitness remains controversial. Venetoclax and hypomethylating agent (ven/HMA) combination therapy has improved outcomes in unfit patients but no prospective study has assessed ven/HMA versus 7&3 as initial therapy in older, fit patients. Given no studies and expectation of ven/HMA use in patients outside of trial criteria, we evaluated retrospective outcomes among newly diagnosed patients. A nationwide electronic health record (EHR)-derived database and the University of Pennsylvania EHR identified 312 patients receiving 7&3 and 488 receiving ven/HMA who were 60-75 years old without history of organ failure. Ven/HMA patients were older and more likely to have secondary AML, adverse cytogenetics, and adverse mutations. Median overall survival (OS) for patients receiving intensive chemotherapy was 22 versus 10 months for ven/HMA (HR 0.53, 95% CI 0.40-0.60). Controlling for measured baseline characteristic imbalances reduced survival advantage by half (HR 0.71, 95% CI 0.53-0.94). A sub-group of patients with equipoise, likelihood at least 30%-70% of receiving either treatment, had similar OS outcomes (HR 1.10, 95% CI 0.75-1.6). Regarding safety outcomes, 60-day mortality was higher for ven/HMA (15% vs. 6% at 60 days) despite higher documented infections and febrile neutropenia for 7&3. In this multicenter real-word dataset, patients selected for intensive chemotherapy had superior OS but a large group had similar outcomes with ven/HMA. Prospective randomized studies, controlling for both measured and unmeasured confounders, must confirm this outcome.

Targeting Menin and CD47 to Address Unmet Needs in Acute Myeloid Leukemia

After forty years of essentially unchanged treatment in acute myeloid leukemia (AML), innovation over the past five years has been rapid, with nine drug approvals from 2016 to 2021. Increased understanding of the molecular changes and genetic ontology of disease have led to targeting mutations in isocitrate dehydrogenase, FMS-like tyrosine kinase 3 (FLT3), B-cell lymphoma 2 and hedgehog pathways. Yet outcomes remain variable; especially in defined molecular and genetic subgroups such as NPM1 (Nucleophosmin 1) mutations, 11q23/KMT2A rearranged and TP53 mutations. Emerging therapies seek to address these unmet needs, and all three of these subgroups have promising new therapeutic approaches. Here, we will discuss the normal biological roles of menin in acute leukemia, notably in KMT2A translocations and NPM1 mutation, as well as current drug development. We will also explore how CD47 inhibition may move immunotherapy into front-line settings and unlock new treatment strategies in TP53 mutated disease. We will then consider how these new therapeutic advances may change the management of AML overall.

Impact of diagnostic genetics on remission MRD and transplantation outcomes in older patients with AML

Older patients with acute myeloid leukemia (AML) have high relapse risk and poor survival after allogeneic hematopoietic cell transplantation (HCT). Younger patients may receive myeloablative conditioning to mitigate relapse risk associated with high-risk genetics or measurable residual disease (MRD), but older adults typically receive reduced-intensity conditioning (RIC) to limit toxicity. To identify factors that drive HCT outcomes in older patients, we performed targeted mutational analysis (variant allele fraction ≥2%) on diagnostic samples from 295 patients with AML aged ≥60 years who underwent HCT in first complete remission, 91% of whom received RIC, and targeted duplex sequencing at remission in a subset comprising 192 patients. In a multivariable model for leukemia-free survival (LFS) including baseline genetic and clinical variables, we defined patients with low (3-year LFS, 85%), intermediate (55%), high (35%), and very high (7%) risk. Before HCT, 79.7% of patients had persistent baseline mutations, including 18.3% with only DNMT3A or TET2 (DT) mutations and 61.4% with other mutations (MRD positive). In univariable analysis, MRD positivity was associated with increased relapse and inferior LFS, compared with DT and MRD-negative mutations. However, in a multivariable model accounting for baseline risk, MRD positivity had no independent impact on LFS, most likely because of its significant association with diagnostic genetic characteristics, including MDS-associated gene mutations, TP53 mutations, and high-risk karyotype. In summary, molecular associations with MRD positivity and transplant outcomes in older patients with AML are driven primarily by baseline genetics, not by mutations present in remission. In this group of patients, where high-intensity conditioning carries substantial risk of toxicity, alternative approaches to mitigating MRD-associated relapse risk are needed.

BCOR and BCORL1 Mutations Drive Epigenetic Reprogramming and Oncogenic Signaling by Unlinking PRC1.1 from Target Genes

Polycomb repressive epigenetic complexes are recurrently dysregulated in cancer. Unlike polycomb repressive complex 2 (PRC2), the role of PRC1 in oncogenesis and therapy resistance is not well-defined. Here, we demonstrate that highly recurrent mutations of the PRC1 subunits BCOR and BCORL1 in leukemia disrupt assembly of a noncanonical PRC1.1 complex, thereby selectively unlinking the RING-PCGF enzymatic core from the chromatin-targeting auxiliary subcomplex. As a result, BCOR-mutated PRC1.1 is localized to chromatin but lacks repressive activity, leading to epigenetic reprogramming and transcriptional activation at target loci. We define a set of functional targets that drive aberrant oncogenic signaling programs in PRC1.1-mutated cells and primary patient samples. Activation of these PRC1.1 targets in BCOR-mutated cells confers acquired resistance to treatment while sensitizing to targeted kinase inhibition. Our study thus reveals a novel epigenetic mechanism that explains PRC1.1 tumor-suppressive activity and identifies a therapeutic strategy in PRC1.1-mutated cancer.

SIGNIFICANCE

We demonstrate that BCOR and BCORL1 mutations in leukemia unlink PRC1.1 repressive function from target genes, resulting in epigenetic reprogramming and activation of aberrant cell signaling programs that mediate treatment resistance. Our study provides mechanistic insights into the pathogenesis of PRC1.1-mutated leukemia that inform novel therapeutic approaches. This article is highlighted in the In This Issue feature, p. 85.

Abstract LB205: The IRF8-MEF2D transcription factor circuit regulated by a druggable multiple post-translational modification (PTM) reader ZMYND8 in acute myeloid leukemia

The transformed state in acute leukemia requires gene regulatory programs involving transcription factors (TFs) and chromatin modulators. Here, we uncover an IRF8-MEF2D TF regulatory circuit as an acute myeloid leukemia (AML)-specific dependency. We discover and characterize the mechanism by which the chromatin ‘reader' ZMYND8 directly activates IRF8 in parallel with the MYC proto-oncogene through their AML-specific enhancers. ZMYND8 is essential for AML proliferation in vitro and in vivo and associates with MYC and IRF8 enhancer elements that we define in cell lines and in patient samples. ZMYND8 occupancy at IRF8 and MYC enhancers requires BRD4, a transcriptional coactivator essential for AML proliferation. We show that ZMYND8 binds to the ET domain of BRD4 via its chromatin reader cassette, which in turn is required for proper chromatin occupancy and maintenance of leukemic growth in vivo. Our results rationalize ZMYND8 as a potential selective therapeutic target for modulating essential transcriptional programs in AML.

Citation Format: Zhendong Cao, Krista A. Budinich, Hua Huang, Bin Lu, Zhen Zhang, Diqiu Ren, Yeqiao Zhou, Yuhan Huang, Bianca Pingul, Molly C. Kingsley, Alexandra K. Lenard, Jun Qi, Martin P. Carroll, Gerd A. Blobel, Robert B. Faryabi, Kathrin M. Bernt, Shelley L. Berger, Junwei Shi. The IRF8-MEF2D transcription factor circuit regulated by a druggable multiple post-translational modification (PTM) reader ZMYND8 in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB205.

Single-cell mutation analysis of clonal evolution in myeloid malignancies

Myeloid malignancies, including acute myeloid leukaemia (AML), arise from the expansion of haematopoietic stem and progenitor cells that acquire somatic mutations. Bulk molecular profiling has suggested that mutations are acquired in a stepwise fashion: mutant genes with high variant allele frequencies appear early in leukaemogenesis, and mutations with lower variant allele frequencies are thought to be acquired later1-3. Although bulk sequencing can provide information about leukaemia biology and prognosis, it cannot distinguish which mutations occur in the same clone(s), accurately measure clonal complexity, or definitively elucidate the order of mutations. To delineate the clonal framework of myeloid malignancies, we performed single-cell mutational profiling on 146 samples from 123 patients. Here we show that AML is dominated by a small number of clones, which frequently harbour co-occurring mutations in epigenetic regulators. Conversely, mutations in signalling genes often occur more than once in distinct subclones, consistent with increasing clonal diversity. We mapped clonal trajectories for each sample and uncovered combinations of mutations that synergized to promote clonal expansion and dominance. Finally, we combined protein expression with mutational analysis to map somatic genotype and clonal architecture with immunophenotype. Our findings provide insights into the pathogenesis of myeloid transformation and how clonal complexity evolves with disease progression.

A randomized trial of three novel regimens for recurrent acute myeloid leukemia demonstrates the continuing challenge of treating this difficult disease

To improve the outcome of relapsed/refractory acute myeloid leukemia (AML), a randomized phase II trial of three novel regimens was conducted. Ninety patients were enrolled and were in first relapse or were refractory to induction/re-induction chemotherapy. They were randomized to the following regimens: carboplatin-topotecan (CT), each by continuous infusion for 5 days; alvocidib (formerly flavopiridol), cytarabine, and mitoxantrone (FLAM) in a timed sequential regimen; or sirolimus combined with mitoxantrone, etoposide, and cytarabine (S-MEC). The primary objective was attainment of a complete remission (CR). A Simon two-stage design was used for each of the three arms. The median age of the patients in the FLAM arm was older at 62 years compared with 55 years for the CT arm and the S-MEC arm. The overall response was 14% in the CT arm (5/35, 90% CI 7%-35%), 28% in the FLAM arm (10/36, 90% CI, 16%-43%), and 16% in the S-MEC arm (3/19, 90% CI, 4%-36%). There were nine treatment-related deaths, seven of which occurred in the FLAM arm with four of these in elderly patients. We conclude that the FLAM regimen had an encouraging response rate and should be considered for further clinical development but should be used with caution in elderly patients.

Anti-CD19 CAR T cells with high-dose melphalan and autologous stem cell transplantation for refractory multiple myeloma

BACKGROUND

Multiple myeloma is usually fatal due to serial relapses that become progressively refractory to therapy. CD19 is typically absent on the dominant multiple myeloma cell population but may be present on minor subsets with unique myeloma-propagating properties. To target myeloma-propagating cells, we clinically evaluated autologous T cells transduced with a chimeric antigen receptor (CAR) against CD19 (CTL019).

METHODS

Subjects received CTL019 following salvage high-dose melphalan and autologous stem cell transplantation (ASCT). All subjects had relapsed/refractory multiple myeloma and had previously undergone ASCT with less than 1 year progression-free survival (PFS).

RESULTS

ASCT + CTL019 was safe and feasible, with most toxicity attributable to ASCT and no severe cytokine release syndrome. Two of 10 subjects exhibited significantly longer PFS after ASCT + CTL019 compared with prior ASCT (479 vs. 181 days; 249 vs. 127 days). Correlates of favorable clinical outcome included peak CTL019 frequency in bone marrow and emergence of humoral and cellular immune responses against the stem-cell antigen Sox2. Ex vivo treatment of primary myeloma samples with a combination of CTL019 and CAR T cells against the plasma cell antigen BCMA reliably inhibited myeloma colony formation in vitro, whereas treatment with either CAR alone inhibited colony formation inconsistently.

CONCLUSION

CTL019 may improve duration of response to standard multiple myeloma therapies by targeting and precipitating secondary immune responses against myeloma-propagating cells.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT02135406.

FUNDING

Novartis, NIH, Conquer Cancer Foundation.

DNMT3A and IDH mutations in acute myeloid leukemia and other myeloid malignancies: associations with prognosis and potential treatment strategies

The development of effective treatment strategies for most forms of acute myeloid leukemia (AML) has languished for the past several decades. There are a number of reasons for this, but key among them is the considerable heterogeneity of this disease and the paucity of molecular markers that can be used to predict clinical outcomes and responsiveness to different therapies. The recent large-scale sequencing of AML genomes is now providing opportunities for patient stratification and personalized approaches to treatment that are based on individual mutational profiles. It is particularly notable that studies by The Cancer Genome Atlas and others have determined that 44% of patients with AML exhibit mutations in genes that regulate methylation of genomic DNA. In particular, frequent mutation has been observed in the genes encoding DNA methyltransferase 3A (DNMT3A), isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2), as well as Tet oncogene family member 2. This review will summarize the incidence of these mutations, their impact on biochemical functions including epigenetic modification of genomic DNA and their potential usefulness as prognostic indicators. Importantly, the presence of DNMT3A, IDH1 or IDH2 mutations may confer sensitivity to novel therapeutic approaches, including the use of demethylating agents. Therefore, the clinical experience with decitabine and azacitidine in the treatment of patients harboring these mutations will be reviewed. Overall, we propose that understanding the role of these mutations in AML biology will lead to more rational therapeutic approaches targeting molecularly defined subtypes of the disease.

Antimicrobial susceptibility and synergy studies of cystic fibrosis sputum by direct sputum sensitivity testing

Standard disc diffusion antimicrobial susceptibility testing (C+S) on individual Pseudomonas aeruginosa colonial morphotypes cultured from cystic fibrosis (CF) sputum has questionable clinical relevance. Direct sputum sensitivity testing (DSST) is a whole-sputum susceptibility test that removes bias associated with selecting individual colonial morphotypes. We sought to determine whether, in principle, the results from DSST support the possibility of improved clinical relevance compared with C+S. Individual (DSSTi) and combination (DSST) susceptibility to gentamicin, tobramycin, ceftazidime and meropenem were determined on 130 sputum samples referred from CF subjects with antibiotic-resistant chronic Gram-negative endobronchial infection. DSSTi and concurrent C+S were compared for categorical susceptibility, synergistic combinations were evaluated and the combination DSST efficacy index (DEI) calculated. Meropenem and tobramycin were the most active individual antibiotics by DSSTi on 89 P. aeruginosa-predominant samples, with 62 % of samples sensitive to each. C+S and DSSTi showed poor agreement (κ ranging from 0.02 to 0.6), discordance ranging from 20 % (meropenem) to 49 % (tobramycin), with DSSTi demonstrating both increased susceptibility and increased resistance. The combination that most frequently had the highest DEI was tobramycin + meropenem, occurring in 76 % of samples. DSSTi appears to be reproducible, yields different antimicrobial susceptibility results from C+S without simply identifying the most resistant isolates and DSST identifies the most effective in vitro antibiotic combinations, providing preliminary proof of concept of the potentially improved clinical relevance of whole-sputum testing. Future studies will determine whether these potential theoretical advantages translate into clinical benefits.

Impact of antibiotic treatment for pulmonary exacerbations on bacterial diversity in cystic fibrosis

BACKGROUND

A diverse array of bacterial species is present in the CF airways, in addition to those recognised as clinically important. Here, we investigated the relative impact of antibiotics, used predominantly to target Pseudomonas aeruginosa during acute exacerbations, on other non-pseudomonal species.

METHODS

The relative abundance of viable P. aeruginosa and non-pseudomonal species was determined in sputa from 12 adult CF subjects 21, 14, and 7 days prior to antibiotics, day 3 of treatment, the final day of treatment, and 10-14 days afterwards, by T-RFLP profiling.

RESULTS

Overall, relative P. aeruginosa abundance increased during antibiotic therapy compared to other bacterial species; mean abundance pre-antibiotic 51.0±36.0% increasing to 71.3±30.4% during antibiotic (ANOVA: F(1,54)=5.16; P<0.027). Further, the number of non-pseudomonal species detected fell; pre-antibiotic 6.0±3.3 decreasing to 3.7±3.3 during treatment (ANOVA: F(1,66)=5.11; P<0.027).

CONCLUSIONS

Antibiotic treatment directed at P. aeruginosa has an additional significant impact on non-pseudomonal, co-colonising species.

The exclusion of dead bacterial cells is essential for accurate molecular analysis of clinical samples

The DNA-based techniques used to detect bacteria in clinical samples are unable to discriminate between live bacteria, dead bacteria, and extracellular DNA. This failure to limit analysis to viable bacterial cells represents a significant problem, leading to false-positive results, as well as a failure to resolve the impact of antimicrobial therapy. The use of propidium monoazide treatment significantly reduces the contribution of dead cells and extracellular DNA to such culture-independent analyses. Here, the increased ability to resolve the impact of antibiotic therapy on Pseudomonas aeruginosa load in cystic fibrosis respiratory samples reveals statistically significant changes that would otherwise go undetected.

Modelling the bacterial communities associated with cystic fibrosis lung infections

In many human diseases that cystic fibrosis (CF) patients suffer from, for example, lung infections, bacteria have been considered to grow as biofilms. The ability of key CF pathogens such as Pseudomonas aeruginosa to resist antibiotic therapies may be due to the poor drug penetration of these biofilms. The overall aim of this study was to develop biofilm models in vitro that resembled the bacterial species composition of CF sputa. Here, this was a step towards a longer term goal of forming multiple bacterial biofilm models in vitro that would serve, in turn, as better assays of antibiotic susceptibilities than conventionally grown cells. Biofilm models were constructed from 31 CF sputum samples, using a modified microtitre plate assay. Three forms of assessment of these biofilms were made, namely, the mass, microscopic analysis and species composition. Species composition in sputa and biofilms, characterised by terminal restriction fragment length polymorphism (T-RFLP) analysis of ribosomal gene polymerase chain reaction (PCR) products amplified from directly extracted nucleic acids, indicated that the bacterial community in sputa was well reproduced in the biofilm models. Typically, fresh sputa contained 4.6 +/- 2.3 bacterial species, with the species number decreasing to 4.0 +/- 1.6 over 5 days-this was not statistically significant (p = 0.29). This study outlines a novel methodology by which to generate and study bacterial biofilms communities. It is also hoped that the versatility of this in vitro approach, combined with its simplicity and high reproducibility, will make it an effective system to study CF sputum biofilm development and, in the longer term, serve as a means of assessing antibiotic susceptibilities.

Use of 16S rRNA gene profiling by terminal restriction fragment length polymorphism analysis to compare bacterial communities in sputum and mouthwash samples from patients with cystic fibrosis

The bacterial communities present in the oral cavity and the lungs of 19 adult cystic fibrosis (CF) patients were compared by using terminal restriction fragment length polymorphism analysis of 16S rRNA gene PCR products amplified from nucleic acids extracted directly from bacteria in clinical samples. Sputum samples were not found to be subject to profound contamination by oral cavity bacteria. Evidence of colonization of the CF lung by certain oral bacterial species was found.

Inhaled heparin in cystic fibrosis

Cystic fibrosis (CF) is characterised by inspissated airway secretions and chronic endobronchial infection associated with exuberant neutrophilic inflammation. Unfractionated heparin may be mucolytic and has demonstrated a number of anti-inflammatory properties; however, further safety data are needed in these subjects who are at risk of airway bleeding. The current study aimed to assess the medium-term safety and tolerability of moderately high-dose inhaled heparin in CF adults and to explore possible in vivo mucolytic and anti-inflammatory outcomes. A randomised, double-blind, placebo-controlled crossover study of twice daily inhalation of 50,000 IU of heparin for 2 weeks was undertaken in CF adults, with a 1-week washout period. Eighteen subjects were randomised and 14 (mean+/-sd age 23+/-7.8 yrs and percentage-predicted forced expiratory volume in one second 52.1+/-15.56%) completed the study protocol. Heparin neither affected blood coagulation parameters nor resulted in any increase in adverse events. Heparin inhalation had no significant effect upon forced expiratory volume in one second, symptoms of sputum clearance or sputum inflammatory markers. The current pilot study demonstrated no evidence of improved sputum clearance with 50,000 IU of inhaled heparin given twice daily to adult cystic fibrosis subjects. However, inhaled heparin was safe and the future evaluation of larger doses over a longer period may be warranted.

characterization of bacterial community diversity in cystic fibrosis lung infections by use of 16s ribosomal DNA terminal restriction fragment length polymorphism profiling

Progressive loss of lung function resulting from the inflammatory response to bacterial colonization is the leading cause of mortality in cystic fibrosis (CF) patients. A greater understanding of these bacterial infections is needed to improve lung disease management. As culture-based diagnoses are associated with fundamental drawbacks, we used terminal restriction fragment (T-RF) length polymorphism profiling and 16S rRNA clone data to characterize, without prior cultivation, the bacterial community in 71 sputa from 34 adult CF patients. Nineteen species from 15 genera were identified in 53 16S rRNA clones from three patients. Of these, 15 species have not previously been reported in CF lung infections and many were species requiring strict anaerobic conditions for growth. The species richness and evenness were determined from the T-RF length and volume for the 71 profiles. Species richness was on average 13.3 +/- 7.9 per sample and 13.4 +/- 6.7 per patient. On average, the T-RF bands of the lowest and highest volumes represented 0.6 and 59.2% of the total volume in each profile, respectively. The second through fifth most dominant T-RF bands represented 15.3, 7.5, 4.7, and 2.8% of the total profile volume, respectively. On average, the remaining T-RF bands represented 10.2% of the total profile volume. The T-RF band corresponding to Pseudomonas aeruginosa had the highest volume in 61.1% of the samples. However, 18 other T-RF band lengths were dominant in at least one sample. In conclusion, this reveals the enormous complexity of bacteria within the CF lung. Although their significance is yet to be determined, these findings alter our perception of CF lung infections.

TEL-JAK2 constitutively activates the extracellular signal-regulated kinase (ERK), stress-activated protein/Jun kinase (SAPK/JNK), and p38 signaling pathways

The ets transcription factor, TEL, undergoes chromosomal rearrangements with the tyrosine kinase JAK2. TEL-JAK2 is constitutively active, confers cell line factor independence, and activates signal transducer and activator of transcription-1 (STAT1), STAT3, and STAT5. Data from bone marrow transplantation models suggest that STAT5 activation does not account for the entire disease phenotype induced by TEL-JAK2. This study examined additional signaling pathways that are activated by TEL-JAK2. TEL-JAK2 expression in Ba/F3 cells results in constitutive association and tyrosine phosphorylation of Shc and Ship-1 and, consequently, recruitment of Grb2 to TEL-JAK2. Direct Grb2 recruitment is also possible because a putative Grb2 binding site, Tyr314, is present on TEL-JAK2(5-19) and TEL-JAK2(5-12). Studies with a TEL-JAK2(5-19)Tyr314Phe mutant support a role for Tyr314 in Grb2 recruitment, because Grb2 association with TEL-JAK2(5-19)Tyr314Phe is significantly reduced. Interestingly, TEL-JAK2(5-19)Tyr314Phe shows reduced Ras activation when compared with TEL-JAK2(4-17), TEL-JAK2(5-12), and TEL-JAK2(5-19). Analysis of extracellular signal-regulated kinase-1/2 (ERK1/2), stress-activated protein/Jun kinase (SAPK/JNK), and p38 demonstrates the activation of SAPK/JNK and phosphorylation of p38 by all TEL-JAK2 isoforms. TEL-JAK2(5-12) and TEL-JAK2(5-19) preferentially phosphorylate ERK2, whereas TEL-JAK2(4-17) phosphorylated ERK2 at lower levels. Inhibition studies demonstrated that ERK1/2 activation was necessary for Ba/F3 factor independence mediated by TEL-JAK2(5-19), while inhibition of SAPK/JNK or p38 activity had no effect. Our data reveal the requirement of ERK activation by TEL-JAK2(5-19) in Ba/F3 cells and suggest that TEL-JAK2 leukemogenic potential may be mediated in part through ERK1/2.

Interleukin 5 release into asthmatic airways 4 and 24 hours after endobronchial allergen challenge: its relationship with eosinophil recruitment

Interleukin 5 (IL-5), a cytokine with a range of activities on eosinophils, has been implicated in the allergic asthmatic reaction. We have investigated the kinetics of release of this cytokine into asthmatic airways as well as its relationship to eosinophil recruitment following allergen challenge. Twelve asthmatic patients underwent endobronchial allergen challenge and bronchoalveolar lavage (BAL) fluid was obtained either 4 h (n=6) or 24 h (n=6) after challenge. Four hours after challenge, levels of IL-5 were significantly increased in BAL fluid (10-fold concentration obtained from the allergen-challenge site compared with the saline control (median 2.67 pg/ml, range 1.0-7.4 pg/ml vs 1.0 pg/ml <1.0-2.4 pg/ml, P<0.05). At 24 h levels of IL-5 increased further at the allergen site but not at the saline control lavage (31.1 pg/ml, range 3.6-59. 0 pg/ml vs 1.5 pg/ml, range <1.5-4.9 pg/ml, respectively P<0.02). At 4h there was almost a three fold increase in IL-5 level, whereas at 24 h IL-5 levels were 20-fold greater. Differential cell counts showed that eosinophil numbers obtained 4 and 24 h after allergen challenge were 7 and 32 times higher than numbers after saline challenge. The parallel increase of eosinophil numbers and IL-5 concentrations in BAL fluid suggests that this cytokine may contribute to the eosinophil recruitment observed into asthmatic airways after allergen challenge.

Endobronchial allergen challenge

LEAC offers a very practical means of studying the pathophysiology of asthma. Despite the local nature of the challenge, LEAC often has a significant effect on FEV1 and may cause short-term destabilization of asthma. In common with other bronchoscopic methods used to study human asthma, samples obtained by LEAC show a considerable degree of variability and it is therefore necessary to use groups of 12-15 subjects to minimize the risk of Type II statistical errors. Comparisons between different studies of allergen exposure are made difficult by a variety of technical considerations. Chief among these are subject selection, the technique used for allergen exposure, the timing of sampling, and the analysis techniques. Dose-response studies in nonasthmatic allergic subjects indicate that the degree of BAL eosinophilia is related to the dose of antigen [17] but there is as yet no agreement on how LEAC might be standardized. Notwithstanding these reservations, local endobronchial allergen challenge has already yielded valuable information on the pathophysiology of asthma and will remain a useful complement to other investigational techniques in the future exploration of this disease.

Infected suture anchors in the shoulder

Symptomatic anterior glenohumeral instability secondary to a Bankart lesion may require surgical reconstruction and repair of labral pathology. In this report, a Bankart repair was performed using metallic suture anchors. An infection developed around the anchors necessitating their removal. To our knowledge, this is the first report of an infection associated with a suture anchor device.

Leukocyte recruitment after local endobronchial allergen challenge in asthma. Relationship to procedure and to airway interleukin-8 release

We have investigated the profile of cellular recruitment into asthmatic airways after allergen and saline exposure and its relationship to interleukin-8 (IL-8) release. Fiberoptic bronchoscopy was used to instill allergen into the middle lobe while the right upper lobe received a sham saline challenge. Bronchoalveolar lavage (BAL) of both sites was performed either 4 or 24 h later. Neutrophil numbers in BAL fluid obtained 4 and 24 h after challenge were 17 and 48 times higher than prechallenge numbers (p < or = 0.001), but there was no statistically significant difference between the numbers of neutrophils at the two sites. In contrast, eosinophil numbers were increased by 6- and 20-fold, respectively, at 4 and 24 h at allergen-challenged as compared with saline-challenged sites (p < 0.005 and p < 0.02, respectively). Baseline concentrations of IL-8 in BAL fluid were undetectable in most cases. Four hours after allergen or saline exposure, BAL fluid IL-8 concentrations were: median, 200 pg/ml; range, 20 to 750 pg/ml and median, 123 pg/ml; range, < 20 to 800 pg/ml, respectively. These declined to 23 pg/ml (range, < 20 to 126 pg/ml) and 43 pg/ml (range < 20 to 130 pg/ml), respectively, 24 h after exposure. There was a significant correlation between neutrophil numbers and IL-8 concentrations 4 h after saline exposure. These findings indicate that neutrophil infiltration is a nonspecific response to the procedure of bronchoscopy and lavage, in contrast to eosinophil recruitment, which is an allergen-specific phenomenon, and it suggests that IL-8 release may be involved in neutrophil recruitment.

Cellular and mediator responses twenty-four hours after local endobronchial allergen challenge of asthmatic airways

The effects of acute allergen exposure on bronchoalveolar lavage cells and mediators and mucosal inflammatory cells were evaluated in 10 subjects with atopic asthma who underwent lavage and biopsy 24 hours after segmental endobronchial allergen challenge. Increased numbers of bronchoalveolar lavage eosinophils were retrieved from the allergen-challenged sites compared with the saline-challenged sites (mean 21.4 vs 1.5 x 10(3) cells/ml; p < 0.02). Numbers of neutrophils and proportions of CD4+, CD8+, CD25+, and HLA-DR+ T cells were similar at the saline- and allergen-challenged sites. In contrast to the bronchoalveolar lavage findings, eosinophil numbers were not increased in the bronchial submucosa or epithelium. There was also no significant difference in neutrophils, mast cells, CD3+, CD4+, or CD8+ T cells in the submucosa after allergen challenge, but the number of activated (CD25+) T lymphocytes in the mucosa did increase after allergen challenge. Allergen challenge did not induce any significant change in endothelial expression of P-selectin, E-selectin, intercellular adhesion molecule-1, or vascular cell adhesion molecule-1. CD11a+ and very late antigen-4+ cell numbers were similar in the saline- and allergen-challenged sites. This study suggests that in patients with very mild asthma, local allergen challenge induces persistent bronchoalveolar lavage eosinophilia, but the recruitment process seems to have diminished or ceased by 24 hours.

Safety aspects of local endobronchial allergen challenge in asthmatic patients

Local endobronchial allergen challenge is being increasingly used to investigate the role of allergic inflammation in asthma. However, little information is available about the safety of this procedure and the changes induced in airway physiology. BAL and biopsy were performed at 10 min and at 4 to 6 h, or 24 h after segmental allergen challenge in 49 patients with atopic asthma. Two hours after challenge, FEV1 was reduced from 97.6 +/- 13.9 (mean +/- SD) to 83.4 +/- 21.7% predicted. FEV1 remained reduced at 4 to 6 h (87.7 +/- 20.4%), but it had nearly returned to baseline by 24 h (93.2 +/- 14.0%). When endobronchial challenge was combined with BAL and biopsy, the initial fall in FEV1 was slightly greater (from 101.8 +/- 14.2 to 78.5 +/- 13.6%). Bronchial responsiveness to methacholine was measured in 10 subjects, and it showed a twofold increase 24 h after local challenge and lavage. Significant changes in FEV1 and methacholine PC20 were still detectable 72 h after challenge. Widespread wheezing occurred in 29% of the subjects, but none of the them had to be admitted to hospital. We conclude that local endobronchial allergen challenge, although producing measurable changes in airway physiology, is in general well tolerated and is an acceptable method to investigate airway pathophysiologic processes in patients with mild to moderate asthma.

Early identification of interleukin-16 (lymphocyte chemoattractant factor) and macrophage inflammatory protein 1 alpha (MIP1 alpha) in bronchoalveolar lavage fluid of antigen-challenged asthmatics

Accumulation of CD4+ interleukin (IL)-2R+ lymphocytes in the airways of asthmatics is generally attributed to the presence of chemoattractant cytokines. The precise mechanism for the initiation of the earliest CD4+ lymphocyte infiltration and activation is unknown. In this study, we describe for the first time the presence of lymphocyte chemoattractant activity in the bronchoalveolar lavage (BAL) fluid obtained from asthmatics 6 h after antigen challenge. The majority of the chemoattractant activity at this early time point is represented by IL-16 (lymphocyte chemoattractant factor), a CD4+ cell-specific chemoattractant and growth factor. In addition to IL-16, macrophage inflammatory protein 1 alpha (MIP1 alpha) chemotactic bioactivity was detected in significant levels. While IL-16, MIP1 alpha, and IL-8 were all identified by enzyme-linked immunosorbent assay, the great majority of the lymphocyte chemoattractant activity in the BAL fluid after antigen challenge is attributable to IL-16 and MIP1 alpha. There were no detectable levels of IL-16 nor MIP1 alpha in BAL fluid of antigen-challenged normal subjects nor atopic nonasthmatics nor in saline-challenged lobes from the asthmatics. The identification of multiple lymphocyte chemoattractants early after antigen challenge suggests a complex cellular, as well as chemoattractant cytokine, profile in initiating the CD4+ T cell-mediated inflammatory process that is specific for the atopic asthmatic phenotype.

Efficacy of radioprotective agents in preventing small and large bowel radiation injury

PURPOSE

A variety of adjuvant treatments and cytoprotective agents have been proposed to lessen the toxicity of radiation therapy. The following study was designed to evaluate the benefit of six agents or combinations using anastomotic bursting strength as a measure of transmural radiation injury.

METHODS

The 40-Gy study consisted of the following. Seventy-two male Sprague-Dawley rats were divided into eight equal groups: nonradiated control, radiated untreated control, and six radiated treated groups. The radioprotective treatments included ribose-cysteine (Rib-Cys), WR-2721, glutamine, vitamin E, MgCl2/adenosine triphosphate, and RibCys/glutamine in combination. Radiated animals received 40 Gy to the abdomen. Two weeks after radiation, all animals underwent small bowel and colonic resection with primary anastomosis. Animals were sacrificed one week postoperatively, at which time anastomoses were evaluated and bursting strengths determined. The 70-Gy study consisted of the following. The same protocol was repeated for five groups of nine rats divided into nonradiated, radiated untreated, and three radiated treated groups receiving RibCys (8 mmol/kg), RibCys (20 mmol/kg), and WR-2721. All radiated animals received 70-Gy doses.

RESULTS

In the 40-Gy group, there were 10 radiation-related deaths and 6 anastomotic leaks among 70 rats studied. None of the differences between groups were significant. Nonradiated control group small bowel and large bowel anastomotic bursting pressures were significantly elevated compared with all radiated groups. Compared with radiated controls, there were significant improvements in small bowel bursting strength in the RibCys, WR-2721, RibCys-glutamine, and vitamin E groups and significant improvement in colonic bursting strength in MgCl2/adenosine triphosphate, WR-2721, and RibCys groups. In the 70-Gy group, all nine nonradiated control rats survived. All eight untreated radiated control rats died, four of eight WR-2721 animals died (P = 0.03), all RibCys (8 mmol/kg) animals died (P = 0.03), and three of nine treated with RibCys (20 mmol/kg) survived (P = 0.08).

CONCLUSIONS

WR-2721 and RibCys gave consistent protection against large and small bowel radiation injury. The lower incidence of treatment-related toxicity and potentially equal or greater radioprotective effects may make RibCys more clinically useful than WR-2721.

Bronchial biopsy evidence for leukocyte infiltration and upregulation of leukocyte-endothelial cell adhesion molecules 6 hours after local allergen challenge of sensitized asthmatic airways

We have examined the mucosal changes occurring in bronchial biopsies from six atopic asthmatics 5-6 h after local endobronchial allergen challenge and compared them with biopsies from saline-challenged segments from the same subjects at the same time point. All the subjects developed localized bronchoconstriction in the allergen-challenged segment and had a decrease in forced expiratory volume in 1 s (FEV1) (P < 0.01) and a decrease in their methacholine provocative concentration of agonist required to reduce FEV1 from baseline by 20% (P < 0.05) 24 h postchallenge. At 6 h we observed an increase in neutrophils (P = 0.03), eosinophils (P = 0.025), mast cells (P = 0.03), and CD3+ lymphocytes (P = 0.025), but not in CD4+ or CD8+ lymphocyte counts. We also detected an increase in endothelial intercellular adhesion molecule type 1 (P < 0.05) and E-selectin (P < 0.005), but not vascular cell adhesion molecule type 1 expression with a correlative increase in submucosal and epithelial LFA+ leucocytes (P < 0.01). Thus, in sensitized asthmatics, local endobronchial allergen instillation leads to an increased inflammatory cell infiltrate of the airway mucosa that involves upregulation of specific adhesion molecules expressed on the microvasculature.

Respiratory muscle function in patients with asbestos-related pleural disease

The effect of asbestos-related pleural disease (ARPD) on the generation of maximum respiratory pressure was investigated in 11 male patients with ARPD mean age 57 years, range 45-74, and mean duration of asbestos exposure of 9.9 years, range 5-16. There were three smokers, seven ex-smokers and one non-smoker. Breathlessness ranged from grade 1-3 on the MRC score. The extent of pleural disease was calculated using a score based on the ILO score for pleural disease. Full respiratory function tests, global respiratory muscle strength and diaphragmatic strength were assessed. Respiratory muscle strength, including diaphragm strength, was normal. Recoil pressure was high or at the upper limit of normal in four patients and correlated with chest radiograph score for pleural disease (r = 0.65, P < 0.02). There was no difference in either global respiratory muscle or diaphragmatic strength between patients with and without involvement of one or both costophrenic angles or between patients with mild or severe breathlessness. We conclude that respiratory muscle strength is not importantly reduced in ARPD, and it is unlikely that weakness contributes to breathlessness in these patients. By contrast reduced chest wall compliance is likely to be an important factor in breathlessness in some cases.

Protein kinase C-mediated serine phosphorylation directly activates Raf-1 in murine hematopoietic cells

We have previously found that Raf-1, which is activated by hematopoietic growth factors in association with phosphorylation, is required for hematopoietic cell proliferation. Recently, 12-O-tetradecanoylphorbol 13-acetate has been found to mediate Raf-1 phosphorylation, suggesting that protein kinase C (PKC) may be involved in the Raf-1 activation mechanism(s). Since PKC can be activated by hematopoietic growth factors, it was investigated as a potential "Raf-1 kinase-kinase." Results demonstrate that bryostatin 1, a pharmacologic activator of PKC, induces activation of Raf-1 in FDC-P1 cells. PKC inhibitors H7 and staurosporine block both bryostatin 1- and interleukin-3-mediated Raf-1 phosphorylation and FDC-P1 cell proliferation. Additionally, an antisense c-raf oligodeoxyribonucleotide specifically inhibits bryostatin 1-mediated proliferation, indicating a necessary role for Raf-1 in PKC signaling. Purified PKC can phosphorylate Raf-1 serine residues to high stoichiometry in vitro. Comparative phosphopeptide maps localize two PKC phosphorylation sites to Raf-1 phosphopeptides isolated from hematopoietic growth factor- or bryostatin 1-stimulated cells. The sites of PKC-mediated Raf-1 phosphorylation are deduced to be Ser497 and Ser619. Furthermore, PKC-mediated serine phosphorylation is sufficient to activate the enzymatic function of Raf-1 in vitro. These findings demonstrate that activated PKC can promote hematopoietic cell growth by regulating the enzymatic activity of Raf-1 through direct serine phosphorylation.

Nasal intermittent positive pressure ventilation in acute exacerbations of chronic obstructive pulmonary disease--a preliminary study

Ten patients (two male) suffering from acute exacerbations of long-standing chronic obstructive pulmonary disease and admitted in hypoxic, hypercapnic respiratory failure were treated with Nasal Intermittent Positive Pressure Ventilation (NIPPV) plus supplemental oxygen, on a general medical ward. The median (range) pH on admission was 7.30 (7.20-7.35), the median age was 67 years (47-77) with an FEV1 (percent of predicted) of 30 (17-39). On admission the median arterial oxygen tension (PaO2) was 4.71 kPa (3.45-6.26) on air, and the carbon dioxide tension (PaCO2) was 7.68 kPa (6.85-9.83). With controlled oxygen therapy there was no significant improvement in PaO2, but the median PaCO2 increased significantly to 9.75 kPa (7.04-11.70) (P < 0.05). By using NIPPV with supplemental oxygen it was possible to significantly improve the median PaO2 to 11.25 kPa (6.70-26.90) (P < 0.01) without worsening PaCO2 levels (8.96 kPa; 6.85-13.10). NIPPV was applied by a senior, respiratory physiotherapist and used intermittently depending on patient tolerance and clinical response. The median total time on NIPPV was 27 h, delivered over 1-5 days. One patient found the mask difficult to tolerate beyond a short period of time. NIPPV was well accepted on a general ward by nursing staff. Three patients later died with progressive hypercapnia, despite an initial response; with one of these patients also receiving intubation and mechanical ventilation. A further patient also received intubation and mechanical ventilation and was eventually discharged. NIPPV plus supplemental oxygen offers a method to correct hypoxaemia on a general medical ward without worsening hypercapnia for acute on chronic, hypoxic, hypercapnic respiratory failure, and warrants further investigation.

Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease

Acute exacerbations of chronic obstructive airways disease (COAD) are a common cause of admission to hospital, and have a high mortality. Nasal intermittent positive pressure ventilation (NIPPV) has been used successfully in patients with respiratory failure due to neuromuscular and skeletal disorders, but the outcome of treatment in patients with COAD is less well known. We carried out a prospective randomised controlled trial of conventional treatment versus conventional treatment plus NIPPV, in 60 patients with acute ventilatory failure due to exacerbations of COAD. For the NIPPV group there was a rise in pH, compared with a fall in the controls (mean difference of change between the groups 0.046 [95% CI 0.06-0.02, p < 0.001]), and a larger fall in PaCO2 (mean difference in change between the groups 1.2 kPa [95% CI 0.45 to 2.03, p < 0.01]). Median visual analogue scores over the first 3 days of admission showed less breathlessness in the NIPPV group (2.3 cm [range 0.1-5.5]) than in the control group (4.5 cm [range 0.9-8.8]) (p < 0.025). Survival rates at 30 days were compared for intention-to-treat and efficacy populations. In the efficacy mortality comparison, mortality in the NIPPV group was reduced: 1/26 vs 9/30 (relative risk = 0.13, CI = 0.02-0.95, p = 0.014). This effect was less in the intention-to-treat analysis: 3/30 vs 9/30 (relative risk = 0.33, CI = 0.10-1.11, p = 0.106). In patients with acute ventilatory failure due to COAD who received NIPPV there was a significant rise in pH, a reduction in PaCO2 and breathlessness, and reduced mortality.

BMT for severe aplastic anemia using cyclosporine

Between 1984 and 1991 24 patients with severe aplastic anemia (SAA) were transplanted with HLA identical sibling donor BM. The overall long-term survival was 79 +/- 8%. The average age was 21 years (range 4-53 years) and the median pre-transplant disease duration was 35 days (range 12-2998 days). Over one-half (15 of 24) of the patients had received > 10 units of blood product transfusions prior to BMT. The pre-transplant conditioning regimen consisted of 200 mg/kg cyclophosphamide (CY). Cyclosporine (CYA) was administered from 2 days prior to BMT and continued for 6-12 months. Two of the 24 patients failed to achieve primary engraftment (FTE). One of these patients had autologous recovery of BM function and is alive and well. Five of the 22 patients who engrafted failed to sustain engraftment (FTSE). Of these, three are alive and well following a second BMT or marrow boost. Only 1 of the 22 patients who engrafted had clinically significant (i.e. Stage II-IV) acute GVHD. No patient developed chronic GVHD. Our results indicate that BMT following a regimen consisting of CY with the continuous use of CYA in the post-transplant period is well tolerated and associated with excellent long-term survival. The high incidence of secondary graft instability (i.e. FTSE), however, suggests that future studies should focus on post-transplantation immunomodulation.

Four interleukin-2 surface binding proteins detected in rat spleen cells

Four specific interleukin-2 (IL-2) surface binding proteins can be detected by covalent cross-linking of [125I]IL-2 to rat spleen cells that have been activated with various stimuli including concanavalin A (Con A), phytohaemagglutinin (PHA), calcium ionophore, and phorbol dibutyrate (PDB) with or without calcium ionophore. These four cross-linked proteins could not be demonstrated in either unstimulated T cells or in activated T cells when binding was performed in the presence of a 20-100-fold excess of unlabelled IL-2. The molecular weights of the four cross-linked proteins, after subtraction of the molecular weight contribution of IL-2 are: 53,000, 70,000, 90,000 and 118,000. The 53,000 MW protein was identified as the rat IL-2 receptor (IL-2R) alpha-chain by immune precipitation. Additionally, results suggest that the rat IL-2R alpha-chain is tightly complexed to both the 118,000 and 90,000 MW IL-2 binding proteins. Purification of surface labelled proteins from activated cells using IL-2 affinity chromatography yields four proteins with similar molecular weight to those identified by cross-linking plus an additional non-ligand cross-linked protein of 46,000 MW. The 46,000 MW band may be a non-binding associated protein since it was not seen following [125I]IL-2 binding cross-linking. Tryptic digests and two-dimensional separation of the affinity-isolated proteins indicate that unique peptide maps are generated for the 46,000, 53,000 and 70,000 MW proteins and excludes the possibility that the bands identified by cross-linking represents cross-linking of multiple ligands to the 53,000 MW subunit. However, the 90,000 and 118,000 MW bands yield peptide maps that closely resemble each other suggesting that these binding proteins may be related. These results suggest that at least four IL-2 surface binding proteins may constitute the rat IL-2R system.

Domiciliary nocturnal nasal intermittent positive pressure ventilation in hypercapnic respiratory failure due to chronic obstructive lung disease: effects on sleep and quality of life

BACKGROUND

Domiciliary assisted ventilation, using negative or positive pressure devices, is an effective treatment for respiratory failure due to chest wall deformity and neuromuscular disease. Negative pressure ventilators have been used with some success in patients with chronic obstructive lung disease in hospital, but attempts to continue treatment at home have been disappointing. This study evaluates the practicalities of nasal intermittent positive pressure ventilation at home in patients with chronic obstructive lung disease and the effect on sleep and quality of life.

METHODS AND RESULTS

Twelve patients with chronic obstructive lung disease and hypercapnic respiratory failure received nasal intermittent positive pressure ventilation at home during sleep. At six months eight were continuing with the ventilation. One patient had died and three had withdrawn because they were unable to sleep with the equipment. Full polysomnography performed during ventilation in patients continuing treatment at six months showed an increase in mean PaO2 of 11% (+2% to +23%) and lower mean transcutaneous carbon dioxide tensions (by -2.7 (-1.3 to -5.1) kPa) overnight compared with spontaneous breathing before the start of nasal intermittent positive pressure ventilation. Total sleep time and sleep efficiency changed during ventilation by +72.5 (+21 to +204) minutes and +5% (-3% to +30%) respectively; sleep architecture and the number of arousals were unchanged. Quality of life did not change but was no worse during ventilation. At one year seven patients were still using the ventilator and PaCO2 and bicarbonate ion concentration during the day had improved further by comparison with the values at six months (change from baseline -1.7 (-2.1 to -0.6) kPa, p less than 0.05, and -6.3 (-11.9 to -4) mmol/l, p less than 0.05).

CONCLUSIONS

Nasal intermittent positive pressure ventilation can be used effectively at home during sleep in selected patients with chronic obstructive lung disease. Its future place in management can be established only by formal comparison with long term oxygen therapy.

Erythropoietin induces Raf-1 activation and Raf-1 is required for erythropoietin-mediated proliferation

Erythropoietin mediates the rapid phosphorylation of Raf-1 in the murine cell lines HCD-57 and FDC-P1/ER, which proliferate in response to this cytokine. Phosphorylation occurs at both serine and tyrosine residues and as such is similar to the Raf-1 phosphorylation seen after interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor, and interleukin-2 stimulation in other murine cell lines. Such data suggest that these growth factors may share a common mechanism(s) of Raf-1 phosphorylation. Furthermore, in association with Raf-1 phosphorylation, erythropoietin induces a 2-3-fold increase in Raf-1 kinase activity as measured in immune complex kinase assays in vitro. Finally, a c-raf antisense oligodeoxyribonucleotide, which specifically decreases intracellular Raf-1 levels, also substantially inhibits both erythropoietin and IL-3-directed DNA synthesis. Together, these results provide evidence that activated Raf-1 is a necessary component of erythropoietin and IL-3 growth signaling pathways.

Sniff esophageal and nasopharyngeal pressures and maximal relaxation rates in patients with respiratory dysfunction

Sniff esophageal pressure (Pes) and maximal relaxation rate (MRR, percent pressure loss/10 ms) are useful measurements of inspiratory muscle performance, but they require the passage of an esophageal balloon. We have examined the relationship between sniff esophageal and nasopharyngeal pressures (sniff Pes, sniff Pnp) and maximal relaxation rates (Pes MRR, Pnp MRR) in 13 patients with chronic obstructive pulmonary disease (COPD), five with intrapulmonary fibrosis (IPF), and seven with the "shrinking lung syndrome" of systemic lupus erythematosus (SLE). The ratio sniff Pnp/Pes (mean +/- SD) was 0.65 +/- 0.15 in COPD, 0.76 +/- 0.18 in IPF, and 0.91 +/- 0.03 in SLE. The ratio Pnp/Pes MRR was 1.20 +/- 0.2 in COPD, 1.14 +/- 0.12 in IPF, and 1.07 +/- 0.13 in SLE. We confirm that the transmission of pleural pressure to the upper airways during brief dynamic maneuvers is impaired in the presence of airway obstruction and lung fibrosis. We conclude that measurements of sniff Pnp and Pnp MRR are of limited value in patients with abnormal lung mechanics.

Interleukin-3 and granulocyte-macrophage colony-stimulating factor mediate rapid phosphorylation and activation of cytosolic c-raf

Interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor induce the rapid phosphorylation of the c-raf protein in the growth factor-dependent FDC-P1 and DA-3 murine myeloid cell lines. Furthermore, immunoprecipitates of c-raf isolated from growth factor-stimulated cells demonstrate a marked increase in intrinsic protein kinase activity as measured in vitro. IL-3 and granulocyte-macrophage colony-stimulating factor induce phosphorylation of c-raf at both serine and tyrosine residues. Antiphosphotyrosine immunoprecipitates from IL-3-stimulated cells demonstrate the rapid and coordinate phosphorylation of both c-raf and a protein co-migrating with the 140-kDa putative IL-3 receptor component. Collectively, the findings of rapid and coordinate ligand-induced phosphorylation of a potential IL-3 growth factor receptor component and cytoplasmic c-raf with concomitant c-raf activation provide a cogent sequential molecular model for linking external growth stimuli to intracellular signal transduction events.

Disodium cromoglycate inhibits activation of human inflammatory cells in vitro

Recent clinical studies indicate that disodium cromoglycate (DSCG) may have a direct effect on inflammatory cells because the drug reversed various changes in leukocyte function, such as increased membrane-receptor expression and enhanced cytotoxic capacity observed in peripheral white blood cells from subjects with asthma undergoing allergen-inhalation challenge. In the present study, we have demonstrated that DSCG, at low concentrations (a concentration of drug required to produce 50% inhibition, approximately 10(-8) mol/L) and in a time-dependent fashion, directly inhibited the activation in vitro of human neutrophils, eosinophils, and monocytes. Peripheral blood leukocytes were incubated with the synthetic chemoattractant, formyl-methionyl-leucyl-phenylalanine (at an optimal concentration of 10(-8) mol/L), and activation was assessed by measuring increases in the percentages of complement and IgG (Fc) rosettes as well as the enhanced capacity of these cells to kill target organisms (schistosomula of Schistosoma mansoni). DSCG at a concentration of 10(-7) mol/L totally inhibited both the formyl-methionyl-leucyl-phenylalanine-induced enhancement of complement and IgG rosettes, as well as increased schistosomular killing. These observations indicate that DSCG directly inhibits the secretory properties of inflammatory cells and that in turn might have important implications in modulating mechanisms contributing to the inflammatory component of asthma and allergic disease. It may also help to explain why compounds with considerably greater mast cell stabilizing properties than DSCG have been so disappointing when they are evaluated clinically.

Enhancement of leukocyte cytotoxicity after exercise-induced asthma

We have previously shown that there were elevations of neutrophil chemotactic activity (NCA) and increases in the percentages of neutrophil and monocyte complement rosettes after exercise-induced asthma (EIA). These observations suggested that leukocyte activation may occur after EIA, possibly as a result of the release of mast-cell-associated mediators. In the present study, we have attempted to establish whether neutrophils and monocytes are functionally altered after EIA as assessed by changes in their cytotoxic capacity. Cytotoxicity was assessed by a direct visual killing assay using opsonized (complement-coated) schistosomula of Schistosoma mansoni as target organisms. Neutrophils and mononuclear cells obtained from 8 patients after exercise-induced asthma (EIA+ve) had increased cytotoxicity for opsonized schistosomula for as long as 60 min after exercise. These changes were preceded by elevations in the concentrations of serum high molecular weight NCA (which were maximal at 10 min after exercise). In asthmatic patients who did not develop exercise-induced asthma (EIA-ve), no significant increases in neutrophil or mononuclear cell killing of schistosomula, or serum NCA concentrations, were observed. There was a highly significant correlation (p less than 0.001) between the reduction in FEV1 and the increases in neutrophil cytotoxicity. In 5 EIA+ve patients, administration of disodium cromoglycate (cromolyn) prior to the exercise task inhibited both the enhancement in neutrophil and mononuclear cell cytotoxicity, as well as the elevations in circulating NCA and the reductions in FEV1.(ABSTRACT TRUNCATED AT 250 WORDS)