The influence of clinical risk factors on pre-operative B-type natriuretic peptide risk stratification of vascular surgical patients.

The role of the revised cardiac risk index in risk stratification has recently been challenged by studies reporting on the superior predictive ability of pre-operative B-type natriuretic peptides. We found that in 850 vascular surgical patients initially risk stratified using B-type natriuretic peptides, reclassification with the number of revised cardiac risk index risk factors worsened risk stratification (p < 0.05 for > 0, > 2, > 3 and > 4 risk factors, and p = 0.23 for > 1 risk factor). When evaluated with pre-operative B-type natriuretic peptides, none of the revised cardiac risk index risk factors were independent predictors of major adverse cardiac events in vascular patients. The only independent predictor was B-type natriuretic peptide stratification (OR 5.1, 95% CI 1.8-15 for the intermediate class, and OR 25, 95% CI 8.7-70 for the high-risk class). The clinical risk factors in the revised cardiac risk index cannot improve a risk stratification model based on B-type natriuretic peptides.

Coupling between p210bcr-abl and Shc and Grb2 adaptor proteins in hematopoietic cells permits growth factor receptor-independent link to ras activation pathway.

Enforced expression of p210bcr-abl transforms interleukin 3 (IL-3)-dependent hematopoietic cell lines to growth factor-independent proliferation. It has been demonstrated that nonreceptor tyrosine kinase oncogenes may couple to the p21ras pathway to exert their transforming effect. In particular, p210bcr-abl was recently found to effect p21ras activation in hematopoietic cells. In this context, experiments were performed to evaluate a protein signaling pathway by which p210bcr-abl might regulate p21ras. It was asked whether Shc p46/p52, a protein containing a src-homology region 2 (SH2) domain, and known to function upstream from p21ras, might form specific complexes with p210bcr-abl and thus, possibly alter p21ras activity by coupling to the guanine nucleotide exchange factor (Sos/CDC25) through the Grb2 protein-Sos complex. This latter complex has been previously demonstrated to occur ubiquitously. We found that p210bcr-abl formed a specific complex with Shc and with Grb2 in three different murine cell lines transfected with a p210bcr-abl expression vector. There appeared to be a higher order complex containing Shc, Grb2, and bcr-abl proteins. In contrast to p210bcr-abl transformed cells, in which there was constitutive tight association between Grb2 and Shc, binding between Grb2 and Shc was Steel factor (SLF)-dependent in a SLF-responsive, nontransformed parental cell line. The SLF-dependent association between Grb2 and Shc in nontransformed cells involved formation of a complex of Grb2 with c-kit receptor after SLF treatment. Thus, p210bcr-abl appears to function in a hematopoietic p21ras activation pathway to allow growth factor-independent coupling between Grb2, which exists in a complex with the guanine nucleotide exchange factor (Sos), and p21ras. Shc may not be required for Grb2-c-kit interaction, because it fails to bind strongly to c-kit.

Molecular heterogeneity of adult Philadelphia chromosome-positive acute lymphoblastic leukemia.

The (9;22) translocation which produces the Philadelphia (Ph1) chromosome activates the abl oncogene from chromosome 9 by recombination with the bcr gene from chromosome 22. This fusion gene is transcribed into a new 8.5-kilobase chimeric mRNA which is translated into a novel Mr 210,000 fusion protein which has a protein tyrosine kinase activity that is greatly increased in comparison to the activity of the normal abl protein. Studies from this laboratory and others have shown that virtually all patients with chronic myelogenous leukemia have this new bcr/abl fusion gene. In contrast to these findings in chronic myelogenous leukemia, a small number of patients with Ph1(+) acute lymphoblastic leukemia (ALL) have been studied and were found to lack the bcr/abl fusion gene [bcr(-)], but to have a new activation of abl, by recombination with an as yet undetermined region on chromosome 22. In this study, nine adults with Ph1(+)-ALL have been examined for evidence of a bcr/abl fusion gene. Of the nine patients, five have a bcr/abl recombination, whereas the remaining four patients do not. In contrast, the children studied to date have all been bcr(-). These data suggest that adults with Ph1(+)-ALL are a more heterogeneous group on a molecular level than are children, and that further studies will be required to determine the spectrum of molecular defects in patients with Ph1(+)-ALL, and the relationship of these various molecular defects to the clinical disease state of the individuals.

Adaptive response to hypoxia and remote ischaemia pre-conditioning: a new hypoxia-inducible factors era in clinical medicine.

Transient ischaemia leads to tolerance to subsequent protracted ischaemia. This 'ischaemia pre-conditioning' results from the induction of numerous protective genes, involved in cell metabolism, proliferation and survival, in antioxidant capacity, angiogenesis, vascular tone and erythropoiesis. Hypoxia-inducible factors (HIF) play a pivotal role in this transcriptional adaptive response. HIF prolyl hydroxylases (PHDs), serving as oxygen sensors, control HIFα degradation. HIF-mediated ischaemic pre-conditioning can be achieved with the administration of PHD inhibitors, with the attenuation of organ injury under various hypoxic and toxic insults. Clinical trials are currently under way, evaluating PHD inhibitors as inducers of erythropoietin. Once their safety is established, their potential use might be further tested in clinical trials in various forms of acute ischaemic and toxic organ damage. Repeated transient limb ischaemia was also found to attenuate ischaemic injury in remote organs. This 'remote ischaemic pre-conditioning' phenomenon (RIP) has been extensively studied recently in small clinical trials, preceding, or in parallel with an abrupt insult, such as myocardial infarction, cardiac surgery or radiocontrast administration. Initial results are promising, suggesting organ protection. Large-scale multi-centre studies are currently under way, evaluating the protective potential of RIP in cardiac surgery, in the management of myocardial infarction and in organ transplantation. The mechanisms of organ protection provided by RIP are poorly understood, but HIF seemingly play a role as well. Thus, Inhibition of HIF degradation with PHD inhibitors, as well as RIP (in part through HIF), might develop into novel clinical interventions in organ protection in the near future.

Chromatin alterations surrounding the BCR/ABL fusion gene in K562 cells.

Chronic myelogenous leukemia (CML) is characterized by the presence of a novel fusion gene comprised of portions of the BCR gene from chromosome (ch) 22 and the ABL gene from ch 9. The present study was designed to identify regulatory DNA regions as determined by DNAase I hypersensitivity to address the question of whether altered chromatin contributes to changes in ABL expression. We identify five hypersensitive (HS) sites within the abnormal BCR/ABL allele in K562 cells in a pattern different from the normal BCR. The pattern of hypersensitivity is modified when the cells undergo hemin induced differentiation. These results indicate that the normal BCR has a chromatin configuration consistent with active transcription and that the BCR/ABL fusion gene chromatin is different. This may be important in the pathogenesis of CML.

Incidence of pulmonary vein complications after lung transplantation: a prospective transesophageal echocardiographic study.

OBJECTIVES: This study attempted to document the incidence of pulmonary vein complications and their potential relation to clinical outcome in patients after lung transplantation. BACKGROUND: Several case reports have documented the presence of pulmonary venous thrombosis causing graft failure in patients after lung transplantation. Because the presentation of these complications mimics that of other postoperative problems, the true incidence of pulmonary vein abnormalities remains unclear. Transesophageal echocardiography is ideally suited to examine the pulmonary veins in the postoperative setting. METHODS: Twenty-one consecutive patients undergoing lung transplantation at our institution underwent transesophageal echocardiography within 32 days of transplantation (mean [+/- SD] 6.5 +/- 7.8 days). Special attention was placed on visualizing the pulmonary veins. RESULTS: Six (29%) of the 21 patients were noted to have abnormalities of the pulmonary veins in the vicinity of the anastomotic site. After follow-up of 30 days, 4 of these patients (67%) had significant cardiovascular morbidity, and 2 died, compared with 1 (7%) of 15 patients with normal pulmonary veins (p = 0.03). The degree of obstruction of the pulmonary vein appeared to correlate with short-term outcome. CONCLUSIONS: Abnormalities of the pulmonary veins are common after lung transplantation and are easily identified by transesophageal echocardiography. Occlusive thrombi appear to be detrimental to short-term outcome.

Mapping of breakpoints, and relationship to BCR-ABL RNA expression, in Philadelphia-chromosome-positive chronic myeloid leukaemia patients with a breakpoint around exon 14 (b3) of the BCR gene.

The BCR gene, on chromosome 22, is involved in the Philadelphia (Ph1) chromosome which is a characteristic cytogenetic marker of chronic myeloid leukaemia (CML). Breakpoints in CML occur within the M-bcr region (5.8 kb) which encompasses exons 12-15 (b1-b4), and the M-bcr can be conveniently divided into five zones by restriction mapping. One of these zones (3) contains exon b3 which can be either present or absent from the hybrid mRNA, even if it is present in the chimaeric gene. We have mapped the breakpoints around BCR exon b3 and related this to the type of RNA splice site expressed, in CML patients at diagnosis. Breakpoints within zone 3 were restriction mapped to one of six sub-zones and the site related to the type of RNA splice site. Two clusters of breakpoints within zone 3 were observed. One cluster was located around exon b3 and often resulted in deletion of exon b3 from the chimaeric gene. The majority of this cluster expressed b2-a2 spliced RNA, usually as a consequence of a deletion removing exon b3. The second cluster occurred within two sub-zones that spanned an Alu sequence, and 90% of this cluster exhibited b3-a2 spliced RNA. Furthermore, a greater number of patients had entered blast crisis if the RNA contained BCR exon b3 (8 of 10 patients), compared to those with b2-a2 spliced RNA (3 of 12 patients). The high degree of heterogeneity in the site of the breakpoint within zone 3 of the M-bcr, combined with the type of BCR-ABL hybrid mRNA expressed, further implicates BCR exon b3 in the pathogenesis of CML.

BCR/ABL confers growth factor independence upon a murine myeloid cell line.

The BCR/ABL oncogene in chronic myelogenous leukemia produces an activated tyrosine kinase fusion protein (p210). Like other tyrosine kinase oncogenes, BCR/ABL can abrogate the interleukin-3 (IL-3) dependence of lymphoid cell lines. To investigate the ability of BCR/ABL to generate growth factor independence in myeloid cells, the IL-3 dependent myeloid cell line NFS/N1.H7 (H7) was transfected with the p210BCR/ABL-containing plasmid, pGD210. Stable clones A54 and A74 were capable of IL-3 independent growth and tumor formation in syngeneic mice. Relief of growth factor dependence was not mediated by autocrine release of IL-3. The baseline proliferation rate of the BCR/ABL transformed cells was greater than that of the parental H7 cells maximally stimulated by IL-3. Abundant constitutive expression of c-myc, c-jun, and c-fos was observed in the p210BCR/ABL transfectants even in low serum conditions. In contrast, c-myc expression in H7 cells was dependent upon IL-3 stimulation, and neither c-jun nor c-fos was highly expressed following IL-3 stimulation in H7 cells. Thus, BCR/ABL transformation and relief of IL-3 dependence involve not only pathways that can substitute for IL-3 induced growth via tyrosine kinase mediated signals, but also pathways that recruit constitutive c-jun and c-fos expression.

Amplification and sequencing of genomic breakpoints located within the M-bcr region by Vectorette-mediated polymerase chain reaction.

The polymerase chain reaction (PCR) cannot be used to amplify the breakpoint in the chimaeric BCR-ABL gene in CML and acute leukaemias due to the large variation in the sites of breakpoint in the BCR gene (within a 5.8 kb region) and in the ABL gene (within a 150 kb region). The disease state is usually monitored using RNA-PCR to monitor abnormal transcripts. We have used a new modification of the PCR to amplify breakpoints within zone 3 of the M-bcr. A synthetic oligonucleotide linker, the Vectorette, is ligated to restriction digested DNA, and amplification is carried out between primers for a known target sequence and the Vectorette linker. Three Philadelphia chromosome Ph1-positive CML patients with breakpoints within the ALU region of zone 3 have been amplified and the sequence immediately around the breakpoint determined. The breaks occurred within 70 bp and two were only 14 bp apart. The Vectorette-PCR technique has the potential to rapidly identify and sequence breakpoints, and will enable the design of patient-specific primers to monitor disease progression, particularly following bone marrow transplantation.

Role for E2F1 in p210 BCR-ABL downstream regulation of c-myc transcription initiation. Studies in murine myeloid cells.

Experiments were performed to elucidate the mechanism through which p210 BCR-ABL, by its downstream signals, regulates c-myc messenger RNA expression in hematopoietic cells. We studied a model system in which stable expression of p210 BCR-ABL in interleukin-3 (IL-3) dependent murine myeloid cell lines led to growth factor independent transformation. Active c-myc transcription was observed in p210 BCR-ABL transformed cells by nuclear run-on assay, and in heterologous reporter assays performed with the 5' regulatory region of murine c-myc linked to firefly luciferase. Transcription initiation occurred primarily from the P2 promoter in p210 BCR-ABL transformed cells. Cis and trans elements responsible for transcription initiation from the c-myc P2 promoter were studied. Expression of E2F1 protein in p210 BCR-ABL transformed cells accounted, in part, for binding to the E2F site of the P2 c-myc promoter. The functional importance of E2F1 expression in p210 BCR-ABL transformed cells toward c-myc transcription was established in reporter assays performed with the P2 c-myc promoter containing either wild-type or mutant E2F sites. Mutation of the E2F motif of P2 5' c-myc reduced activity of the promoter by 50%. By gel mobility shift, E2F1 was found in P2 c-myc band shift complexes along with the cyclin-dependent kinase 2. Therefore, coupling of E2F to components of the retinoblastoma-cyclin pathway defines a route from p210 BCR-ABL to c-myc transcription, which is required for p210 BCR-ABL transformation.

Variability of right ventricular functional recovery after lung transplantation.

BACKGROUND: The purpose of this study was to assess by echocardiography the effects of lung transplantation on recovery of right ventricular (RV) function in patients with preoperative RV dysfunction. METHODS: Fourteen (20%) of 71 lung transplant recipients were identified by echocardiography as manifesting abnormal RV function before lung transplantation. These 14 patients were selected for follow-up echocardiographic study 8 months after transplantation. RESULTS: RV function improved significantly in the study group. Mean RV end-diastolic area decreased from 26.8 +/- 7.9 cm2 to 20.1 +/- 4.7 cm2 (P < 0.01); mean RV end-systolic area decreased from 21.5 +/- 6.8 cm2 to 13.1 +/- 4.2 (P < 0.01); and mean RV fractional area change (FAC) increased from 20.4 +/- 3.3% to 35.8 +/- 8.9% (P < 0.001). A subgroup of four patients, however, exhibited no change in RV function. Patients who achieved improvement in RV function tended to be younger, had shorter duration of disease before transplantation, and had higher pulmonary arterial (PA) pressures before transplantation (PA systolic, 89 +/- 28 mmHg vs. 38 +/- 11 mmHg, P < 0.001; PA diastolic, 42 +/- 11 mmHg vs. 19 +/- 3 mmHg, P < 0.002). Each of the eight patients with primary pulmonary hypertension exhibited improvement in RV function (mean delta FAC +20.6 +/- 5.9%), while two of three patients with emphysema and both patients with idiopathic pulmonary fibrosis failed to achieve improvement in RV function (mean delta FAC +2.3 +/- 1.2%). CONCLUSIONS: Improvement of RV function assessed by echocardiography occurs after lung transplantation, even in patients with severe preoperative RV dysfunction. However, the degree of improvement is variable and may depend on the degree of RV after-load reduction and the presence or absence of intrinsic myocardial disease. RV ejection parameters do not distinguish between these two possibilities.

The glial spike theory. I. On an active role of neuroglia in spreading depression and migraine.

The propagation mechanism of spreading depression (SD), which has been implicated in the pathophysiology of the neurological auras of migraine, remains enigmatic but is widely believed to depend primarily upon the behaviour of assemblies of neurons. It is proposed here, based upon a program of theoretical research, that the most essential constituent of SD is a slowly propagating, regenerative event in the neuroglial compartment. By altering the neuronal microenvironment, this glial spike helps trigger and coordinate the neuronal depolarization of SD; the glial spike is in turn facilitated by neuronally released agents acting at the neuroglial plasma membrane. The conduction velocity-determining propagation mechanism of SD is further proposed to be a wave of intracellular Ca(2+)-induced Ca2+ release (cytocal wave) that travels through the glial compartment of nervous tissue. Some implications for the improved understanding and clinical management of migraine are suggested. Excitability of glial cells of vertebrates has until now been demonstrated only in vitro, and its physiological significance has remained unknown. This work identifies a macroscopic reaction of neuronal tissue, known from the in vivo vertebrate brain for over 45 years, as a manifestation of neuroglial excitability.

Two-year follow-up in pediatric and adult patients with single-pass lead VDD pacing system.

VDD pacing follow-up is similar in pediatric and adult patients. Atrial and ventricular pacing parameters are stable during 2-year follow-up in children, and single-pass lead VDD pacing is recommended when the sinus node function is normal.

Relation between patent foramen ovale and perfusion abnormalities in acute pulmonary embolism.

The frequency of right-to-left shunt through a patent foramen ovale is increased in hemodynamically stable patients without preexisting cardiopulmonary disease with acute pulmonary embolism. This is associated with a greater degree of perfusion abnormalities as quantified by perfusion scan and the presence of tricuspid regurgitation.

ABL oncogene expression during erythroleukemia cell differentiation.

The translocation between chromosome 9 and chromosome 22 which creates the Philadelphia chromosome moves the ABL oncogene from its normal location on chromosome 9 and fuses it with a portion of the BCR gene on chromosome 22. This new BCR/ABL fusion gene generates a unique 8.7 kilobase (kb) RNA which codes for a new 210 kilodalton (kd, p210) protein which has a protein tyrosine kinase activity that is greatly increased in comparison to the normal ABL protein. The human K562 cell line was derived from a patient with CML, and serves as one model for the regulation of expression of the ABL and BCR/ABL genes. This study examines the expression of the BCR/ABL fusion gene and the normal ABL gene in relation to differentiation and changes in proliferative state. The expression of both the normal ABL transcripts and the BCR/ABL fusion transcript decrease approximately ten-fold when the cells are induced to differentiate with hemin. In contrast, expression of the MYC oncogene is unaffected by hemin-induced differentiation. The results suggest that both ABL and BCR/ABL expression vary in proportion to the differentiation of the cells, but minimally if at all as a function of the cells' proliferative state.

Association between right ventricular function and perfusion abnormalities in hemodynamically stable patients with acute pulmonary embolism.

BACKGROUND/OBJECTIVES: Patients presenting with acute pulmonary embolism associated with hemodynamic compromise exhibit right ventricular enlargement and dysfunction on transthoracic echocardiogram. However, the degree of echocardiographic abnormalities among hemodynamically stable patients without preexisting cardiopulmonary disease during the acute stage of pulmonary embolism, and following treatment, is unknown. Therefore, this study was designed to assess the extent of right ventricular abnormalities detected on transthoracic echocardiogram in patients following acute pulmonary embolism and during treatment with anticoagulation or vena caval interruption. The extent of pulmonary vascular obstruction and complication rate on follow-up were also assessed. DESIGN/INTERVENTIONS: Sixty-four consecutive hemodynamically stable patients without preexisting known cardiopulmonary disorder presenting with acute pulmonary embolism and undergoing treatment with anticoagulation or inferior vena caval interruption were studied. All subjects underwent a two-dimensional transthoracic echocardiogram within 24 h of diagnosis. The degree of perfusion abnormality on lung scan was quantified. Twenty-six patients underwent follow-up echocardiogram and lung scan at 6 weeks. The echocardiographic findings were compared with those obtained from a group of normal control subjects matched for gender and age. RESULTS: Although the mean right ventricular end-diastolic areas did not differ (21.9+/-5.2 cm2 vs 20.1+/-2.9 cm2 for control subjects; p=not significant), the right ventricular end-systolic area was larger in comparison to our series of control subjects (14.6+/-5.1 cm2 vs 11.7+/-2.0 cm2; p=0.025). Fractional right ventricular area change was reduced in the patient group compared with the control subjects (34.3+/-9.0% vs 41.3+/-7.0%; p=0.003). The extent of right ventricular end-systolic area enlargement and decrease in fractional area change did not correlate with the degree of pulmonary vascular obstruction. Patients who were restudied at 6 weeks showed minimal improvement in echocardiographic findings, despite almost complete resolution of perfusion defects on lung scan. CONCLUSIONS: The extent of right ventricular dysfunction in hemodynamically stable, previously normal patients with acute pulmonary embolism does not reflect the extent of the perfusion abnormalities. Further, right ventricular enlargement and systolic dysfunction are present and persistent despite treatment with heparin and warfarin therapy or vena caval interruption.

Diagnosis of patent foramen ovale with transesophageal echocardiography in a patient supported with a left ventricular assist device.

Intracardiac right-to-left shunting through a patent foramen ovale is a known cause of arterial hypoxemia. We present a case report of a patient supported with a left ventricular assist device who had significant right-to-left shunting as visualized with transesophageal echocardiography. When the device was turned off, no further shunting occurred and arterial hypoxemia resolved. Our report is the first visual representation of the anatomy of a patent foramen ovale in a patient supported with a left ventricular assist device.

Coronary angiography in smokers undergoing evaluation for lung transplantation: is routine use justified?

Many patients referred for lung transplantation have a history of smoking. For the exclusion of the possibility of asymptomatic coronary artery disease, these patients undergo coronary angiography as part of their preoperative evaluation. The usefulness of this approach remains unknown. We reviewed the records of all smokers referred for lung transplantation who underwent coronary angiography (n = 77). Nine patients (12%) had significant coronary artery disease; six (8%) of these patients had their clinical management altered because of findings on angiography. Eight of nine patients with coronary artery disease (89%) and all of the six patients (100%) whose management was altered had coronary artery disease risk factors other than a history of smoking; therefore, no patient with clinically significant coronary artery disease had history of smoking as the only risk factor. The presence of other coronary artery disease risk factors was significantly associated (p < 0.0001) with the positive findings on angiography. A nonsignificant trend toward older age was found, and a higher proportion of male patients existed in the group with coronary artery disease. Routine angiography for all patients with a history of smoking referred for angiography is unjustified. A subset of patients with high risk identified primarily by the presence of additional coronary artery disease risk factors may benefit from routine angiography.

Sotalol: a novel beta-blocker with class III anti-arrhythmic activity.

Initially synthesized in 1960, sotalol is a novel beta-adrenoreceptor blocking agent that also possesses class III anti-arrhythmic properties. The drug's ability to lengthen repolarization and prolong effective refractory periods in all cardiac tissues in addition to its beta-blocking effects make sotalol an attractive agent for use in a variety of supraventricular and ventricular arrhythmias.

The combination of coculture and selective assisted hatching: results from their clinical application.

OBJECTIVE: To establish pregnancies using a combination of coculture and selective assisted hatching. DESIGN: Clinical application for a selected group of patients. Not a controlled study. SETTING: Private infertility practice. PATIENTS: Women with high basal FSH levels, ovulatory disorders, and multiple failed IVF attempts. MAIN OUTCOME MEASURES: Pregnancy and implantation rates. RESULTS: Of the 95 patients who had coculture and selective assisted hatching, 45 (47.0%) have an ongoing pregnancy with a 23.0% implantation rate. CONCLUSION: The combination of coculture and assisted hatching produced acceptable pregnancy and implantation rates within the selected patient population.