Abstract 3378: Glutaminase activity determines cytotoxicity of L-asparaginases on leukemia cell lines

L-Asparaginase (ASNase) is a front-line chemotherapy for acute lymphoblastic leukemia (ALL), which acts by deaminating asparagine (Asn) and glutamine (Gln). We and others have shown that its cytotoxicity depends more on Gln than Asn depletion. Novel ASNases with different activities have been developed in an attempt to decrease side effects and allergic reaction. To evaluate the importance of glutaminase activity, we developed a novel form of Helicobacter pylori ASNase (dm HpA) using site-directed mutagenesis, with amino acid substitutions M121C/T169M. This mutant form was designed to have the same asparaginase activity as wild type (wt), but lack glutaminase activity. WT and dm HpA were compared with the clinically used ASNases from E. coli (EcA-II) and Erwinia chrysanthemi (ErA).

Asparaginase and glutaminase activities of each enzyme were measured with Nessler's assay at pH 8.6. The ratio of glutaminase/asparaginase activity was 1.4% for dm HPase, 7.5% for wt HPase, 41% for EcA-II, and 99% for ErA (at 0.6 IU), respectively.

L-Asparaginases (0.01 to 3 IU/ml over 72 hrs) were tested on 8 human leukemia cell lines: pre B ALL (BV173, Nalm-6, RCH-ACV, RS4;11, SEM, SupB15), T cell ALL (Molt-4), and acute promyelocytic leukemia (HL-60). Viable cells were determined by trypan blue exclusion.

Two cell lines which we had previously shown to be Asn-dependent (RS4;11 and SupB15) were equally sensitive to the asparaginase isoforms (>90% kill at 0.03 IU/mL). The other 6 lines were more sensitive to isoforms with higher glutaminase activities (Table). ErA was the most effective on all three cell lines on which it was tested.

These data show that asparaginase activity alone may not be sufficient for ASNase cytotoxicity, and that glutaminase activity may be required for full efficacy. These sensitivities to ASNases match previous data on Asn- and Gln-dependent cell proliferation (Ehsanipour et al., Cancer Research, 2013).

% cell growth inhibition at 3 IU/ml ASNase (n=1-2 for each cell line; nd: not done)Cell linedm HpAwt HpAEcA-IIErARS4;11919291ndSupB15919193ndRCH-ACV13362866SEM22484165BV17324326ndNalm-61621574HL-60204033ndMolt4325963nd

Citation Format: Jean-Hugues Parmentier, Maristella Maggi, Erika Tarasco, Claudia Scotti, Vassilios Avramis, Steven D. Mittelman. Glutaminase activity determines cytotoxicity of L-asparaginases on leukemia cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3378. doi:10.1158/1538-7445.AM2014-3378

Genotype-phenotype correlation in Pompe disease, a step forward

BACKGROUND

Pompe's disease is a progressive myopathy caused by mutations in the lysosomal enzyme acid alphaglucosidase gene (GAA). A wide clinical variability occurs also in patients sharing the same GAA mutations, even within the same family.

METHODS

For a large series of GSDII patients we collected some clinical data as age of onset of the disease, presence or absence of muscular pain, Walton score, 6-Minute Walking Test, Vital Capacity, and Creatine Kinase. DNA was extracted and tested for GAA mutations and some genetic polymorphisms able to influence muscle properties (ACE, ACTN3, AGT and PPARα genes).We compared the polymorphisms analyzed in groups of patients with Pompe disease clustered for their homogeneous genotype.

RESULTS

We have been able to identify four subgroups of patients completely homogeneous for their genotype, and two groups homogeneous as far as the second mutation is defined "very severe" or "potentially less severe". When disease free life was studied we observed a high significant difference between groups. The DD genotype in the ACE gene and the XX genotype in the ACTN3 gene were significantly associated to an earlier age of onset of the disease. The ACE DD genotype was also associated to the presence of muscle pain.

CONCLUSIONS

We demonstrate that ACE and ACTN3 polymorphisms are genetic factors able to modulate the clinical phenotype of patients affected with Pompe disease.

Expanding targets for a metabolic therapy of cancer: L-asparaginase

The antitumour enzyme L-asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1, ASNase), which catalyses the deamidation of L-asparagine (Asn) to L-aspartic acid and ammonia, has been used for many years in the treatment of acute lymphoblastic leukaemia. Also NK tumours, subtypes of myeloid leukaemias and T-cell lymphomas respond to ASNase, and ovarian carcinomas and other solid tumours have been proposed as additional targets for ASNase, with a potential role for its glutaminase activity. The increasing attention devoted to the antitumour activity of ASNase prompted us to analyse recent patents specifically concerning this enzyme. Here, we first give an overview of metabolic pathways affected by Asn and Gln depletion and, hence, potential targets of ASNase. We then discuss recent published patents concerning ASNases. In particular, we pay attention to novel ASNases, such as the recently characterised ASNase produced by Helicobacter pylori, and those presenting amino acid substitutions aimed at improving enzymatic activity of the classical Escherichia coli enzyme. We detail modifications, such as natural glycosylation or synthetic conjugation with other molecules, for therapeutic purposes. Finally, we analyse patents concerning biotechnological protocols and strategies applied to production of ASNase as well as to its administration and delivery in organisms.

Perspective on the evolution of cell-based bone tissue engineering strategies

Despite the compelling clinical needs in enhancing bone regeneration and the potential offered by the field of tissue engineering, the adoption of cell-based bone graft substitutes in clinical practice is limited to date. In fact, no study has yet convincingly demonstrated reproducible clinical performance of tissue-engineered implants and at least equivalent cost-effectiveness compared to the current treatment standards. Here, we propose and discuss how tissue engineering strategies could be evolved towards more efficient solutions, depicting three different experimental paradigms: (i) bioreactor-based production; (ii) intraoperative manufacturing, and (iii) developmental engineering. The described approaches reflect the need to streamline graft manufacturing processes while maintaining the potency of osteoprogenitors and recapitulating the sequence of biological steps occurring during bone development, including vascularization. The need to combine the assessment of efficacy of the different strategies with the understanding of their mechanisms of action in the target regenerative processes is highlighted. This will be crucial to identify the necessary and sufficient set of signals that need to be delivered at the injury or defect site and should thus form the basis to define release criteria for reproducibly effective engineered bone graft substitutes.

Bioinformatic analysis of pathogenic missense mutations of activin receptor like kinase 1 ectodomain

Activin A receptor, type II-like kinase 1 (also called ALK1), is a serine-threonine kinase predominantly expressed on endothelial cells surface. Mutations in its ACVRL1 encoding gene (12q11-14) cause type 2 Hereditary Haemorrhagic Telangiectasia (HHT2), an autosomal dominant multisystem vascular dysplasia. The study of the structural effects of mutations is crucial to understand their pathogenic mechanism. However, while an X-ray structure of ALK1 intracellular domain has recently become available (PDB ID: 3MY0), structure determination of ALK1 ectodomain (ALK1_EC) has been elusive so far. We here describe the building of a homology model for ALK1_EC, followed by an extensive bioinformatic analysis, based on a set of 38 methods, of the effect of missense mutations at the sequence and structural level. ALK1_EC potential interaction mode with its ligand BMP9 was then predicted combining modelling and docking data. The calculated model of the ALK1_EC allowed mapping and a preliminary characterization of HHT2 associated mutations. Major structural changes and loss of stability of the protein were predicted for several mutations, while others were found to interfere mainly with binding to BMP9 or other interactors, like Endoglin (CD105), whose encoding ENG gene (9q34) mutations are known to cause type 1 HHT. This study gives a preliminary insight into the potential structure of ALK1_EC and into the structural effects of HHT2 associated mutations, which can be useful to predict the potential effect of each single mutation, to devise new biological experiments and to interpret the biological significance of new mutations, private mutations, or non-synonymous polymorphisms.

Blood exposure has a negative effect on engineered cartilage

PURPOSE

The aim of this study was to investigate the in vitro effect of different concentrations of blood on the morphological and biochemical properties of engineered cartilage. Previous studies have demonstrated a negative effect of blood on native cartilage; however, the effect of the contact of blood on engineered cartilage is unclear.

METHODS

Articular chondrocytes were isolated from swine joints, expanded in monolayer culture, and seeded onto collagen membranes. The seeded membranes were cultured for 3 days in the presence of different concentrations of peripheral blood. Some samples were retrieved at the end of the blood contact, others after 21 additional days of standard culture conditions, in order to investigate the "long-term effect" of the blood contact.

RESULTS

All seeded samples showed an increase in the weight and an evident cartilage-like matrix production. A concentration-dependent reduction in the mitochondrial activity due to blood contact was shown at the earlier culture time, followed by a partial recover at the longer culture time.

CONCLUSION

A blood contact of 3 days affected the chondrocytes' activity and determined a delay in the maturation of the engineered cartilage. These findings have clinical relevance, as autologous chondrocytes seeded onto biological scaffolds has become an established surgical method for articular cartilage repair. Therefore, further investigation into material sciences should be encouraged for the development of scaffold protecting the reparative cells from the blood insult.

Cell-cycle inhibition by Helicobacter pylori L-asparaginase

Helicobacter pylori (H. pylori) is a major human pathogen causing chronic gastritis, peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue lymphoma. One of the mechanisms whereby it induces damage depends on its interference with proliferation of host tissues. We here describe the discovery of a novel bacterial factor able to inhibit the cell-cycle of exposed cells, both of gastric and non-gastric origin. An integrated approach was adopted to isolate and characterise the molecule from the bacterial culture filtrate produced in a protein-free medium: size-exclusion chromatography, non-reducing gel electrophoresis, mass spectrometry, mutant analysis, recombinant protein expression and enzymatic assays. L-asparaginase was identified as the factor responsible for cell-cycle inhibition of fibroblasts and gastric cell lines. Its effect on cell-cycle was confirmed by inhibitors, a knockout strain and the action of recombinant L-asparaginase on cell lines. Interference with cell-cycle in vitro depended on cell genotype and was related to the expression levels of the concurrent enzyme asparagine synthetase. Bacterial subcellular distribution of L-asparaginase was also analysed along with its immunogenicity. H. pylori L-asparaginase is a novel antigen that functions as a cell-cycle inhibitor of fibroblasts and gastric cell lines. We give evidence supporting a role in the pathogenesis of H. pylori-related diseases and discuss its potential diagnostic application.

Helicobacter pyloril-asparaginase: a promising chemotherapeutic agent

Bacterial L-asparaginases are amidohydrolases that catalyse the conversion of L-asparagine to L-aspartate and ammonia and are used as anti-cancer drugs. The current members of this class of drugs have several toxic side effects mainly due to their associated glutaminase activity. In the present study, we report the molecular cloning, biochemical characterisation and in vitro cytotoxicity of a novel L-asparaginase from the pathogenic strain Helicobacter pylori CCUG 17874. The recombinant enzyme showed a strong preference for L-asparagine over L-glutamine and, in contrast to most L-asparaginases, it exhibited a sigmoidal behaviour towards L-glutamine. The enzyme preserved full activity after 2 h incubation at 45 degrees C. In vitro cytotoxicity assays revealed that different cell lines displayed a variable sensitivity towards the enzyme, AGS and MKN28 gastric epithelial cells being the most affected. These findings may be relevant both for the interpretation of the mechanisms underlying H. pylori associated diseases and for biomedical applications.

Prosthetic joint replacement for long bone metastases: analysis of 154 cases

INTRODUCTION

Metastatic bone disease is the most common cause of malignancies to the skeleton in adults. The treatment of bone metastases is frequently palliative aiming to achieve a satisfactory control of pain and to prevent or to treat pathological fractures. In selected cases the resection of a single bone metastasis may improve the survival of the patients. Our experience with bone metastases located in the appendicular skeleton, between 1992 and 2004, is retrospectively reviewed here.

MATERIALS AND METHODS

We report a series of 154 patients (95 females and 59 males) treated with prosthesis for metastatic bone disease. Lower limb localization was more frequent with 117 cases, while upper limb was affected in 37 cases. Metastatic breast and renal carcinoma predominated and accounted for 66% of the lesions. Indications to surgery were reported, oncologic outcome was evaluated and functional results were obtained by the Musculoskeletal Tumor Society scoring system.

RESULTS

Follow up ranged from 6 months to 12 years (median 26 months). One-year survival was 69.5%, 2-years survival was 44.8%, 5-years survival was 19.5%; and 5 (3.2%) died in the early post surgical period. Functional results were good or higher in 73.8% of patients for the proximal femur, in 50% of patients for the knee and 30.6% of patients for the proximal humerus.

CONCLUSION

In this series, satisfactory results were achieved with few complications. We emphasized the importance of giving the patient a definitive treatment and preventing pathological fractures as they determine disability and a spreading of the tumor in the soft tissues, leading to an increased probability of local recurrence. Prosthetic replacement contributes to an improved quality of life and limb functionality and, in selected cases; this radical surgical approach is indicated as it may improve patient's life expectancy.

Modular prostheses in the treatment of proximal humerus metastases: review of 40 cases

Background

The humerus is the second most common site of metastatic bone disease involving long bones. Tumors which have a predilection for dissemination to bone are those of breast, prostate, thyroid, lung and kidney. The rationale for surgical treatment of these lesions is to prevent or treat pathological fractures in order to relieve pain and improve function.

Materials and methods

Forty patients who had resection of the proximal humerus for metastatic bone disease and reconstruction with a modular prosthesis were retrospectively reviewed.

Results

Mean functional outcome was 73.1% (Enneking score) and better results were achieved when a reverse prosthesis was implanted. Overall survival was 70% at 1 year, 42.5% at 2 years and 20% at 5 years. Local recurrence occurred in 4 patients, each of whom had initially been treated for a pathological fracture.

Conclusions

It is important to follow rational guidelines, like those of Capanna and Mirels, in order to prevent pathological fractures and to give the patient a definitive treatment, as the advances in the management of cancer prolong the survival of these patients. In this series, satisfactory results were obtained, giving the patients an acceptable quality of life.

A tissue engineered osteochondral plug: an in vitro morphological evaluation

Articular cartilage lesions have a poor intrinsic healing potential. The repair tissue is often fibrous, having insufficient biomechanical properties, which could frequently lead to the development of early osteoarthritis. In the last decade, tissue engineering approaches addressed this topic in order to restore joint function with a differentiated and functional tissue. Many biomaterials and techniques have been proposed and some of them applied in clinical practice, even though several concerns have been raised on the quality of the engineered tissue and on its integration in the host joint. In this study, we focused on engineering in vitro a biphasic composite made of cellular fibrin glue and a calcium-phosphate scaffold. Biphasic composites are the latest products of tissue engineering applied to articular cartilage and they seem to allow a more efficient integration of the engineered tissue with the host. However, a firm in vitro bonding between the two components of the composite is a necessary condition to validate this model. Our study demonstrated a gross and microscopic integration of the two components and a cartilage-like quality of the newly formed matrix. Moreover, we noticed an improvement of this integration and GAGs production during the in vitro culture.

Effect of blood on the morphological, biochemical and biomechanical properties of engineered cartilage

The use of autologous chondrocytes seeded onto a biological scaffold represents a current valid tool for cartilage repair. However, the effect of the contact of blood to the engineered construct is unknown. The aim of this work was to investigate in vitro the effect of blood on the morphological, biochemical and biomechanical properties of engineered cartilage. Articular chondrocytes were enzymatically isolated from swine joints, expanded in monolayer culture and seeded onto collagen membranes for 2 weeks. Then, the seeded membranes were placed for 3 days in contact with peripheral blood, which was obtained from animals of the same species and diluted with a standard medium. As controls, some samples were left in the standard medium. After the 3 days' contact, some samples were retrieved for analysis; others were returned to standard culture conditions for 21 additional days, in order to investigate the "long-term effect" of the blood contact. Upon retrieval, all seeded samples showed increasing sizes and weights over time. However, the samples exposed to blood presented lower values with respect to the controls. Biochemical evaluation demonstrated a reduction in the mitochondrial activity due to blood contact at the early culture time (3 days post blood contact), followed by a partial recovery at the longer culture time (21 days post blood contact). Histological evaluation demonstrated evident cartilage-like matrix production for both groups. Biomechanical data showed a reduction of the values, followed by stabilization, regardless of the presence of blood. Based on the data obtained in this study, we can conclude that blood contact affects the chondrocyte activity and determines a delay in the dimensional growth of the engineered cartilage; however, at the experimental times utilized in this study, this delay did not affect the histological pattern and the biomechanical properties of the construct.

Expression, purification and preliminary crystallographic studies on the catalytic region of the nonreceptor tyrosine kinase Fes

The proto-oncogene tyrosine protein kinase c-fps/fes encodes a structurally unique protein (Fes) of the nonreceptor protein-tyrosine kinase (PTK) family. Its expression has been demonstrated in myeloid haematopoietic cells, vascular endothelial cells and in neurons. In human-derived and murine-derived cell lines, the activated form of this kinase can induce cellular transformation; moreover, it has been shown that Fes is involved in the regulation of cell-cell and cell-matrix interactions mediated by adherens junctions and focal adhesions. The N-terminus of Fes contains the FCH (Fps/Fes/Fer/CIP4 homology) domain, which is unique to the Fes/Fer kinase family. It is followed by three coiled-coil domains and an SH2 (Src-homology 2) domain. The catalytic region (Fes-CR) is located at the C-terminus of the protein. The successful expression, purification and crystallization of the catalytic part of Fes (Fes-CR) are described.

Structural Basis of Affinity Maturation of the TEPC15/Vκ45.1 Anti-2-phenyl-5-oxazolone Antibodies

Affinity maturation is a process that leads to the emergence of more efficient antibodies following initial antigen encounter and represents a key strategy of the adaptive immunity of vertebrate organisms. Earlier and detailed sequence studies of the antibody response to a model antigen, the hapten 2-phenyl-5-oxazolone (phOx), define three different classes of antibodies. Class I antibodies use the V(H)Ox1/V(kappa)Ox1 gene pair and dominate the early stages of the anti-phOx response, class II antibodies use the V(kappa)Ox1 gene but a different V(H) segment and are common in the intermediate stages, and class III antibodies use the TEPC15/V(kappa)45.1 genes and play the greatest role in the late stages. Only the crystal structure of one anti-phOx antibody, the class II NQ10/12.5 Fab fragment, has been described. Here we report the crystal structures of the scFv form of the low and high affinity anti-phOx class III antibodies NQ10/1.12 and NQ16/113.8 complexed with the hapten. The two antibodies differ by nine amino acid substitutions, all located in the V(H) domain. Analysis of the two structures shows that affinity maturation results from an increase in surface complementarity, as a consequence of a finely tuned and highly concerted process chaperoned by the somatic mutations, and implies a more efficient hapten-induced fit in the mature antibody. The data also demonstrate that class III antibodies respond in a completely different way to the architectural problem of binding phOx compared to the class II antibody NQ10/12.5.

Lack of molecular relationships between lipid peroxidation and mitochondrial DNA single strand breaks in isolated rat hepatocytes and mitochondria

We investigated the molecular relationships between lipid peroxidation and mitochondrial DNA (mtDNA) single strand breaks (ssb) in isolated rat hepatocytes and mitochondria exposed to tert-butylhydroperoxide (TBH). Our results show that mtDNA ssb induced by TBH are independent of lipid peroxidation and dependent on the presence of iron and of hydroxyl free radicals. These data contribute to the definition of the mechanisms whereby mtDNA ssb are induced and provide possible molecular targets for the prevention of this kind of damage in vivo.

Helicobacter pylori releases a factor(s) inhibiting cell cycle progression of human gastric cell lines by affecting cyclin E/cdk2 kinase activity and Rb protein phosphorylation through enhanced p27(KIP1) protein expression

Helicobacter pylori, the main cause of chronic gastritis, plays a central role in the etiology of peptic ulcer disease and gastric cancer. In vitro studies have shown that H. pylori increases gastric epithelial cell turnover, thus increasing the risk for the development of neoplastic clones. The mechanisms by which H. pylori promotes perturbation of cell proliferation are not yet elucidated. To investigate whether products released by H. pylori in culture media interfere with cell cycle progression of human gastric epithelial cells, four cell lines (MKN 28, MKN 7, MKN 74, and AGS) were incubated in the presence of H. pylori broth culture filtrate. Cell cycle analysis showed that a H. pylori-released factor(s) significantly inhibited the G1- to S-phase progression of MKN 28 and MKN 7 cell lines, with a reversible, nonlethal mechanism, independent of the expression of VacA, CagA, and/or urease. The cell cycle inhibition occurred concomitantly with an increase in p27(KIP1) protein levels, a reduction in Rb protein phosphorylation on serine residues 807-811, and a significant decrease in cyclin E-associated cdk2 activity. In contrast, the cell cycle progression of MKN 74 and AGS cell lines was not affected by the H. pylori-released factor(s). In normal human fibroblasts, G1-phase cell accumulation was concomitant with the reduction in Rb protein phosphorylation; that, however, appeared to be dependent on p21(WAF1/CIP1) rather than on p27(KIP1) protein. A preliminary characterization showed that the molecular mass of the partially purified cell cycle inhibitory factor(s) was approximately 40 kDa. These results suggest that H. pylori releases a soluble factor(s) that may affect cell cycle progression of gastric epithelial cells through elevated levels of cdk inhibitor p27(KIP1). This factor(s) might act in vivo on noncolonized distant cells, the most proliferating cells of human gastric mucosa.

Preliminary observations on haemodynamics during physiological stress conditions following 'double-orifice' mitral valve repair

OBJECTIVE

The 'double-orifice' (DO) technique has been proposed to simplify mitral valve repair (MVRep) in particular settings of mitral insufficiency. However, the haemodynamic effects of such a redesigned valve are poorly documented, particularly during stress conditions. Thus, we sought to evaluate the haemodynamic changes during exercise conditions after the DO procedure.

METHODS

Twenty-seven selected patients were enrolled for this study. Mean age was 60 +/- 14 years (range 31--80 years). All patients had had severe mitral regurgitation and normal LV function preoperatively, and had undergone DO as isolated procedure for MVRep. Annular remodelling was associated in 24 cases (Carpentier classic ring in 13 patients and autologous pericardium in 11 patients, respectively). Postoperatively, haemodynamic data were recorded at baseline and during supine exercise test at submaximal workloads by means of transthoracic echocardiography. A logistic regression analysis was applied to evaluate the association between the observed haemodynamic changes and surgical technique.

RESULTS

Mean follow-up was 47 +/- 20 months. Significant residual mitral insufficiency (grade three over four) was found in five patients at baseline assessment, and in six patients at peak exercise. Transmitral pressure gradient showed a significant (P < 0.001) increase in both peak and mean values at peak exercise (from 7 +/- 4 to 17 +/- 10 and from 3 +/- 2 to 8 +/- 6 mmHg, respectively). Pulmonary hypertension was observed in six patients (moderate in all cases) at rest and in 13 patients (moderate in seven cases and severe in five cases) at peak exercise. We did not find any correlation between the haemodynamic data and surgical factors.

CONCLUSIONS

This study indicates that though effective mitral valve competence is achieved in the majority of operated patients, DO repair may induce impaired diastolic mitral dynamism in some cases, particularly during exercise conditions. Further investigations are required to thoroughly elucidate the overall mechanics of a DO valve, especially at strenuous cardiocirculatory states.

Genetic diversity and dynamics of Sinorhizobium meliloti populations nodulating different alfalfa cultivars in Italian soils

We analyzed the genetic diversity of 531 Sinorhizobium meliloti strains isolated from nodules of Medicago sativa cultivars in two different Italian soils during 4 years of plant growth. The isolates were analyzed for DNA polymorphism with the random amplified polymorphic DNA method. The populations showed a high level of genetic polymorphism distributed throughout all the isolates, with 440 different haplotypes. Analysis of molecular variance allowed us to relate the genetic structure of the symbiotic population to various factors, including soil type, alfalfa cultivar, individual plants within a cultivar, and time. Some of these factors significantly affected the genetic structure of the population, and their relative influence changed with time. At the beginning of the experiment, the soil of origin and, even more, the cultivar significantly influenced the distribution of genetic variability of S. meliloti. After 3 years, the rhizobium population was altered; it showed a genetic structure based mainly on differences among plants, while the effects of soil and cultivar were not significant.

Production of endogenous nitric oxide in chronic obstructive pulmonary disease and patients with cor pulmonale. Correlates with echo-Doppler assessment

Exhaled nitric oxide (NO) production in stable chronic obstructive pulmonary disease (COPD) has been loosely related to the severity of illness, being significantly reduced in the most severe cases. Pulmonary hypertension is associated with lower NO output from the lung. In this study expired NO was measured in patients with severe stable COPD with or without cor pulmonale (CP). Echocardiographic estimates of right heart function, lung function, diffusion capacity, respiratory muscle strength, and arterial blood gases were obtained in 34 consecutive patients with stable COPD (mean age, 68 +/- 7 yr). Expired NO was measured by chemiluminiscence to obtain fractional exhaled concentrations at peak (FENOp) and at plateau (FENOpl) points of the single-breath curve and resting NO output (V NO). All measurements of expired NO output, FENOp, FENOpl and V NO showed a negative correlation with both systolic pulmonary artery pressure (Pspa) (r = -0.51, -0.63, and -0.63, respectively, p < 0.01 for all) and right ventricle wall dimension (r = -0.41, -0.59, and -0.43, respectively, p < 0.05 for all), but not with any measurement of lung function. When the patients were divided according to the Pspa using a cutoff limit of 35 mm Hg, those subjects with CP showed lower FENOp (13.2 +/- 4.0 versus 36.7 +/- 30.8 ppb, p < 0.05), FENOpl (5.7 +/- 1.9 versus 8.9 +/- 4.7 ppb, p < 0.05), and V NO (69. 2 +/- 5.6 versus 107.6 +/- 14.6 nl/ min, p = 0.02) than did those with a normal resting Pspa. NO production from the airways was significantly lower and inversely related to development of CP in patients with severe COPD. Impaired endothelial release may account for the reduced levels of expired NO.

The antiproliferative effect of beta-carotene requires p21waf1/cip1 in normal human fibroblasts

In normal human fibroblasts, beta-carotene induces a cell-cycle delay in the G1 phase independent of its provitamin A activity via a mechanism not yet elucidated. In this study we provide biochemical evidence showing that delayed progression through the G1 phase occurs concomitantly with: an increase in both nuclear-bound and total p21waf1/cip1 protein levels; an increase in the amount of p21waf1/cip1 associated with cdk4; the inhibition of cyclin D1-associated cdk4 kinase activity; and a reduction in the levels of hyperphosphorylated forms of retinoblastoma protein, and particularly, in phosphorylated Ser780. The role of p21waf1/cip1 in the antiproliferative effect of the carotenoid was further supported by genetic evidence that neither changes in cell-cycle progression nor in the phosphorylation status of retinoblastoma protein were observed in p21waf1/cip1-deficient human fibroblasts treated with beta-carotene. These results clearly demonstrate that p21waf1/cip1 is involved directly in the molecular pathway by which beta-carotene inhibits cell-cycle progression.