Sporadic primary pulmonary hypertension is associated with germline mutations of the gene encoding BMPR-II, a receptor member of the TGF-beta family

BACKGROUND

Primary pulmonary hypertension (PPH), resulting from occlusion of small pulmonary arteries, is a devastating condition. Mutations of the bone morphogenetic protein receptor type II gene (BMPR2), a component of the transforming growth factor beta (TGF-beta) family which plays a key role in cell growth, have recently been identified as causing familial PPH. We have searched for BMPR2 gene mutations in sporadic PPH patients to determine whether the same genetic defect underlies the more common form of the disorder.

METHODS

We investigated 50 unrelated patients, with a clinical diagnosis of PPH and no identifiable family history of pulmonary hypertension, by direct sequencing of the entire coding region and intron/exon boundaries of the BMPR2 gene. DNA from available parent pairs (n=5) was used to assess the occurrence of spontaneous (de novo) mutations contributing to sporadic PPH.

RESULTS

We found a total of 11 different heterozygous germline mutations of the BMPR2 gene in 13 of the 50 PPH patients studied, including missense (n=3), nonsense (n=3), and frameshift (n=5) mutations each predicted to alter the cell signalling response to specific ligands. Parental analysis showed three occurrences of paternal transmission and two of de novo mutation of the BMPR2 gene in sporadic PPH.

CONCLUSION

The sporadic form of PPH is associated with germline mutations of the gene encoding the receptor protein BMPR-II in at least 26% of cases. A molecular classification of PPH, based upon the presence or absence of BMPR2 mutations, has important implications for patient management and screening of relatives.

Expression of angiogenesis-related molecules in plexiform lesions in severe pulmonary hypertension: evidence for a process of disordered angiogenesis

Pulmonary arteries of patients with severe pulmonary hypertension (SPH) presenting in an idiopathic form (primary PH-PPH) or associated with congenital heart malformations or collagen vascular diseases show plexiform lesions. It is postulated that in lungs with SPH, endothelial cells in plexiform lesions express genes encoding for proteins involved in angiogenesis, in particular, vascular endothelial growth factor (VEGF) and those involved in VEGF receptor-2 (VEGFR-2) signalling. On immunohistochemistry and in situ hybridization, endothelial cells in the plexiform lesions expressed VEGF mRNA and protein and overexpressed the mRNA and protein of VEGFR-2, and the transcription factor subunits HIF-1alpha and HIF-1beta of hypoxia inducible factor, which are responsible for the hypoxia-dependent induction of VEGF. When compared with normal lungs, SPH lungs showed decreased expression of the kinases PI3 kinase and src, which, together with Akt, relay the signal transduction downstream of VEGFR-2. Because markers of angiogenesis are expressed in plexiform lesions in SPH, it is proposed that these lesions may form by a process of disordered angiogenesis.

Nitric oxide is the endogenous neurotransmitter of bronchodilator nerves in humans

In human airways, there is a prominent neural bronchodilator mechanism which is non-adrenergic. In human tracheal segments, we have demonstrated that this response is mediated entirely by nitric oxide (NO), since an inhibitor of NO synthesis, L-NG-nitroarginine methyl ester (L-NAME) (10(-4) M) abolishes this neural response. Identification of the neurotransmitter of this bronchodilator pathway may now make it possible to study its role in physiological control of airway calibre and in airway disease.

Vasovagal reactions may occur after orthotopic heart transplantation

OBJECTIVES

This study evaluated the ability of patients to manifest vasovagal reactions after orthotopic heart transplantation.

BACKGROUND

Paradoxic stimulation of left ventricular baroreceptors may be the afferent limb of the vasovagal reflex in humans. Orthotopic heart transplantation causes surgical denervation of these receptors and would therefore be expected to abolish the vasovagal reflex.

METHODS

To attempt to confirm this hypothesis, 10 patients with orthotopic heart transplantation underwent both head-up tilt testing while resting on a saddle support and testing for parasympathetic innervation of the donor heart before and after atropine infusion. Native and donor heart sinus rates were monitored by using an esophageal pill electrode throughout tilting and during parasympathetic testing.

RESULTS

Unexpectedly, seven patients had vasovagal responses at saddle support tilt testing, during which native heart rate decreased by 25 +/- 7 beats/min and mean arterial blood pressure decreased by 55 +/- 9 mm Hg. In three of these patients, there was also a decrease in donor heart rate of 23 +/- 26 beats/min. Parasympathetic testing showed possible evidence of donor heart vagal reinnervation in these patients with donor heart bradycardia during tilt but not in those with vasovagal reactions to tilt without slowing of the donor heart rate.

CONCLUSIONS

Vagal efferent reinnervation can occur after orthotopic heart transplantation in humans. However, the absence of such reinnervation in some patients with vasovagal responses to tilt calls into question the role of left ventricular receptors in inducing the vasovagal reaction.

Immunohistology of Epstein-Barr virus-associated antigens in B cell disorders from immunocompromised individuals

Proliferating B cell lesions developing in a series of immunosuppressed organ transplant recipients and patients with X-linked lymphoproliferative syndrome were examined for Epstein-Barr virus and cellular gene expression using immunocytochemistry and immunoblotting techniques. Results indicate that all the lesions examined from the patients in this series expressed Epstein-Barr virus gene products that were consistent with a latent, nonproductive type of infection. No lytic cycle antigens associated with productive viral infection were detected. This pattern is similar to the viral gene expression in normal B cells immortalized by Epstein-Barr virus in vitro. The demonstration in this study of Epstein-Barr virus viral gene expression in posttransplant and X-linked proliferative syndrome B cell disorders provides important new evidence for the primary role of Epstein-Barr virus in the development of these lesions. This is in contrast to the subsidiary role that the Epstein-Barr virus has in the etiology of Burkitt's lymphoma.

Fourteen-year experience with homovital homografts for aortic valve replacement

Two hundred seventy-five unprocessed, viable homograft ("homovital") aortic valves were used for aortic valve replacement in patients aged 1.5 to 79 years (mean 45.8 +/- 19 years) with maximum follow-up of a 14-year period (mean 4.8 years). Ninety-two percent (252 patients) had New York Heart Association class III or IV functional status before operation and 25 underwent emergency operation. Valves were harvested under sterile conditions and kept in nutrient medium 199. Freehand (subcoronary) technique was used in 147 patients and freestanding root replacement was used in 128. Cumulative survival rates for the whole group were 92% +/- 2% at 5 years and 85% +/- 3% at 10 years, as compared with 96% +/- 2% and 94% +/- 4%, respectively, for the 98 patients who underwent isolated root replacement. Multivariate analysis determined that root replacement with associated procedures and operation for prosthetic endocarditis were risk factors for death, whereas previous xenograft valve, operation for endocarditis, and operation for aortic regurgitation were risk factors for reoperation. Actuarial rates for freedom from degenerative valve failure diagnosed at operation, by postmortem examination, or by routine echocardiography were 94% +/- 2% at 5 years and 89% +/- 3% at 10 years. Recipient age younger than 30 years and previous xenograft valve were risk factors for late degeneration. We conclude that homovital valves demonstrate good durability, particularly in patients older than 30 years, who had a 10-year freedom from degeneration rate of 97%.

Coronary artery infusion of neuropeptide Y in patients with angina pectoris

Neuropeptide Y was infused into a coronary artery of 6 patients with typical angina but no significant coronary stenosis. 3 patients had transient myocardial ischaemia, shown by typical pain and electrocardiographic change, at doses of 0.2 pmol/kg per min in 2 patients and 1.0 pmol/kg per min in 1 patient. The arteriographic appearances suggested constriction of small vessels rather than constriction of epicardial coronary arteries. The ischaemia was completely reversed by intracoronary administration of isosorbide dinitrate with no adverse sequelae. This is the first demonstration of myocardial ischaemia in man induced by a peptide neurotransmitter.

Human coxsackie-adenovirus receptor is colocalized with integrins alpha(v)beta(3) and alpha(v)beta(5) on the cardiomyocyte sarcolemma and upregulated in dilated cardiomyopathy: implications for cardiotropic viral infections

BACKGROUND

The coxsackievirus and adenovirus receptor (CAR) was identified as a common cellular receptor for both viruses, but its biological and pathogenic relevance is uncertain. Knowledge of CAR localization in the human cardiovascular system is limited but important with respect to CAR-dependent viral infections and gene transfer using CAR-dependent viral vectors.

METHODS AND RESULTS

Explanted failing hearts from 13 patients (8 with dilated cardiomyopathy [DCM] and 5 with other heart diseases [non-DCM]) and normal donor hearts (n=7) were investigated for the expression levels and subcellular localization of CAR and the adenovirus coreceptors alpha(v)beta(3) and alpha(v)beta(5) integrins. CAR immunoreactivity was very low in normal and non-DCM hearts, whereas strong CAR signals occurred at the intercalated discs and sarcolemma in 5 of the 8 DCM hearts (62.5%); these strong signals colocalized with both integrins. In all hearts, CAR was detectable in subendothelial layers of the vessel wall, but not on the luminal endothelial surface, and on interstitial cells. Human CAR (hCAR) expressed in rat cardiomyocytes was targeted to cell-cell contacts, which resembled CAR localization in DCM hearts and resulted in 15-fold increased adenovirus uptake.

CONCLUSIONS

Low hCAR abundance may render normal human myocardium resistant to CAR-dependent viruses, whereas re-expression of hCAR, such as that observed in DCM, may be a key determinant of cardiac susceptibility to viral infections. Asymmetric expression of hCAR in the vessel wall may be an important determinant of adenovirus tropism in humans. hCAR subcellular localization in human myocardium and hCAR targeting to cell-cell contacts in cardiomyocyte cultures suggest that hCAR may play a role in cell-cell contact formation.

Activation of coagulation and fibrinolysis during cardiothoracic operations

BACKGROUND

During open cardiac operations using cardiopulmonary bypass, there is activation of coagulation and fibrinolysis. We assessed the separate contributions of the surgical procedure itself and cardiopulmonary bypass to this, by studying sequential samples from patients undergoing routine open cardiac operations or thoracic operations without cardiopulmonary bypass.

METHODS

Activation of coagulation and the extent of fibrinolysis were measured from sequential samples obtained before the operation to 48 hours after the operation for 7 thoracic patients and 8 cardiac patients.

RESULTS

In the thoracic group operation length was shorter (p = 0.002), and there was no significant increase in thrombin-antithrombin III complexes or D-dimers until 24 hours postoperatively. In contrast, there was a highly significant increase in thrombin-antithrombin III complexes (p = 0.0043) and D-dimer levels (p = 0.009) during cardiopulmonary bypass. The increase in fibrinolytic activity was caused by an increase in tissue plasminogen activator (p = 0.013). At 48 hours postoperatively, the cardiac patients had a more hypercoagulable state than thoracic patients with significantly higher levels of thrombin-antithrombin III complexes (p = 0.041) and plasminogen activator inhibitor-1 activity (p = 0.0033).

CONCLUSIONS

This study suggests the major activation of coagulation and fibrinolysis seen during cardiac operations is caused by the use of cardiopulmonary bypass.

Routinely performed multiparametric magnetic resonance imaging helps to differentiate common subtypes of renal tumours

OBJECTIVES

To retrospectively evaluate the ability of multiparametric magnetic resonance (MR) imaging to differentiate renal tumours.

METHODS

MR images from 100 consecutive pathologically proven solid renal tumours without macroscopic fat [57 clear cell, 16 papillary and 7 chromophobe renal cell carcinomas (RCCs), 16 oncocytomas and 4 minimal fat angiomyolipomas (AMLs)] between 2009 and 2012 were evaluated. Two radiologists blinded to pathology results independently reviewed double-echo chemical shift, dynamic contrast-enhanced T1- and T2-weighted images and apparent diffusion coefficient (ADC) maps. Signal intensity index (SII), tumour-to-spleen SI ratio (TSR), ADC ratio, wash-in (WiI) and wash-out indices (WoI) between different phases were calculated.

RESULTS

There were significant differences between papillary RCCs and other renal tumours for arterial WiI (P < 0.001), initial WoI (P = 0.006) and ADC ratio (P < 0.001); between chromophobe RCCs and oncocytomas for TSR (P = 0.02), parenchymal WiI (P = 0.03), late WiI (P = 0.02), initial WoI (P = 0.03) and late WoI (P = 0.04); and between clear cell RCCs and oncocytomas for SII (P = 0.01) and parenchymal WiI (P = 0.01). Papillary RCCs were distinguished from other tumours (sensitivity 37.5 %, specificity 100 %) and oncocytomas from chromophobe RCCs (sensitivity 25 %, specificity 100 %) and clear cell RCCs (sensitivity 100 %, specificity 94.2 %).

CONCLUSION

MR imaging provides criteria able to accurately distinguish papillary RCCs from other tumours and oncocytomas from chromophobe and clear cell RCCs.

KEY POINTS

• Multiparametric MR parameters accurately distinguish papillary RCCs with high specificity (100 %). • Oncocytomas can be distinguished from chromophobe RCCs with high specificity (100 %). • Oncocytomas can be distinguished from clear cell RCCs with high specificity (94.2 %). • In oncocytomatosis, imaging follow-up with such parameters analysis could be promoted.

Enhanced deposition of predominantly type I collagen in myocardial disease

The myocardium consists of a muscle fibre array surrounded and interspersed by a network of connective tissue, principally collagen, which maintains the functional integrity of the heart. Changes in collagen composition may therefore contribute to altered ventricular function. Collagen composition was examined in cardiac tissue from 15 patients undergoing orthotopic cardiac transplantation. Of these, 10 had severely impaired left ventricular function due to coronary artery disease. The remaining five had dilated cardiomyopathy. Normal heart tissue was taken at autopsy from 25 patients who died of causes unrelated to cardiovascular disease. Left ventricular collagen concentration, estimated from hydroxyproline levels, increased from 48.6 +/- 4.1 mg/g dry weight of tissue in the control group to 95.3 +/- 9.7 mg/g (P less than 0.01) in patients with dilated cardiomyopathy and to 63.5 +/- 9.8 mg/g in the coronary artery disease group. This increase was attributable to an increase in absolute concentrations of both type I and III collagen, determined by separation of cyanogen bromide peptides by sodium dodecyl sulphate polyacrylamide gel electrophoresis. However, there was a significant decrease in the proportion of type III collagen (compared with type I plus III) from 41.8 +/- 1.1% in controls, to 34.6 +/- 1.5% (P less than 0.01) in the coronary artery disease group and 35.8 +/- 2.8% (P less than 0.05) in the dilated cardiomyopathy group. These results suggest that excessive collagen production, with a preponderance of type I, occurs in these forms of myocardial disease, indicative of a remodelling of the collagen matrix, which, by increasing passive myocardial stiffness may contribute to impaired heart function seen in these groups of patients.

Increased sensitivity of the denervated transplanted human heart to isoprenaline both before and after beta-adrenergic blockade

It is not known whether surgical denervation leads to increased beta-receptor sensitivity after human cardiac transplantation. We assessed cardiac beta-receptor sensitivity by studying the heart rate response to isoprenaline of the denervated donor heart as compared with the innervated recipient heart in eight patients who underwent heterotopic cardiac transplantation and in six patients with orthotopic transplantation. Changes in the donor and recipient hearts seen in these 14 patients were further compared with those seen in 10 normal volunteers. Incremental intravenous infusion of isoprenaline (5, 10, and 15 ng/kg/min) raised heart rate to a greater extent in the donor compared with the recipient hearts in the eight patients who had heterotopic grafts (slopes [beats/min/ng/kg]: donor = +2.26, recipient = +1.59; p less than .01). In addition, the donor hearts of the transplant patients were more sensitive than hearts of the normal volunteers (slopes: donor = +2.26, normal = +0.94; p less than .01). The changes in the two groups of donor hearts were similar (slopes: orthotopic = +2.24, heterotopic = +2.27; NS). The recipient hearts in the patients with heterotopic transplants were more sensitive than the hearts of the normal volunteers (p less than .05), suggesting that the observed differences in isoprenaline sensitivity in the patients with heterotopic grafts were not caused by a decreased sensitivity of the recipient heart. After beta-blockade, the heart rate responses to isoprenaline were attenuated to the same extent in denervated and innervated hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Native low density lipoprotein-induced calcium transients trigger VCAM-1 and E-selectin expression in cultured human vascular endothelial cells

Low density lipoprotein (LDL) interactions with the endothelium are thought to play a major role in the development of atherosclerosis. The mechanism(s) involved are not fully understood, although several lines of evidence support the idea that oxidation of LDL increases its atherogenicity. In this study we report for the first time that native LDL (n-LDL) binding to the LDL receptor (100-700 mug/ml) triggers a rise in intracellular calcium which acts as a second messenger to induce vascular cell adhesion molecule-1 (VCAM-1) expression in human coronary artery (HCAEC) and pig aortic endothelial cells (PAEC) and VCAM-1 and E-selectin expression in human aortic (HAEC) endothelial cells. Preincubation of HCAEC with a monoclonal antibody (IgGC7) to the classical LDL receptor or pretreatment with pertussis toxin blocked the n-LDL-induced calcium transients. Preincubation of each of the endothelial cell lines with the calcium chelator 1,-2-bis(o-aminophenoxy)ethane-N,N,N', N'-tetraacetic acetomethyl ester (BAPTA/AM) prevented the expression of VCAM-1 and E-selectin. The increase in VCAM-1 by n-LDL results in increased monocyte binding to HCAEC which can be attenuated by inhibiting the intracellular calcium rise or by blocking the VCAM-1 binding sites. These studies in human and pig endothelial cells link calcium signaling conferred by n-LDL to mechanisms controlling the expression of endothelial cell adhesion molecules involved in atherogenesis.

Differential leukotriene constrictor responses in human atherosclerotic coronary arteries

BACKGROUND

Leukotrienes are a class of biologically active lipids that have potent effects on the heart. To assess their role in coronary artery disease, we compared the contractile responses of leukotriene C4 (LTC4) and leukotriene D4 (LTD4) and their binding activity in both atherosclerotic and nonatherosclerotic human coronary arteries. We also studied expression of the enzymes that control their formation to understand how the 5-lipoxygenase (5-LO) pathway is activated in the coronary arteries.

METHODS AND RESULTS

The capacity of leukotrienes to affect coronary vessel tone and the influence of atherosclerosis was tested in organ baths. Leukotriene receptors were examined by autoradiography, and antibody binding to the various enzymes responsible for their formation was assessed by use of immunocytochemistry. Nonatherosclerotic coronary artery ring segments were unresponsive to LTC4 and LTD4. In contrast, LTC4 and LTD4 induced concentration-dependent contractions in atherosclerotic coronary arteries. Specific [3H]-LTC4 but not LTD4 binding to atherosclerotic coronary artery was evident, with no evidence of specific binding of [3H]-leukotrienes to nonatherosclerotic coronary artery. High-resolution autoradiography identified specific [3H]-LTC4 binding sites to smooth muscle cell and to regions of intimal proliferation and plaque. Cells showing positive antibody binding to 5-LO, FLAP (5-lipoxygenase activating protein), and leukotriene A4 hydrolase were also present in the coronary arteries and had a similar distribution to macrophages.

CONCLUSIONS

Atherosclerosis is associated with a specific leukotriene receptor(s) capable of inducing hyperreactivity of human epicardial coronary arteries in response to LTC4 and LTD4.

The pathology of the early and late stages of primary pulmonary hypertension

During the course of a case of primary pulmonary hypertension occurring in a 24 year old man lung tissue became available at heart-lung transplantation in 1986 and from a lung biopsy carried out in 1981. In 1986 the sections showed classic plexogenic pulmonary arteriopathy. In 1981 they revealed migration of myofibroblasts into the intima and lumen of pulmonary arteries and arterioles, the identification of the cells being confirmed by electron microscopy. During the five years that the pulmonary vascular pathology progressed to the formation of plexiform lesions there was an increase in the number of bronchiolar endocrine cells that were immunoreactive to bombesin and calcitonin. This study demonstrates that the classic pathogenesis of primary plexogenic pulmonary arteriopathy originates years earlier as a migration of cells of muscular pedigree from the media into the intima of the pulmonary arteries and arterioles.

Expression of adhesion molecules by lp(a): a potential novel mechanism for its atherogenicity

Lp(a) is a major inherited risk factor for premature atherosclerosis. The mechanism of Lp(a) atherogenicity has not been elucidated, but likely involves both its ability to interfere with plasminogen activation and its atherogenic potential as a lipoprotein particle after receptor-mediated uptake. We demonstrate that Lp(a) stimulates production of vascular cell adhesion molecule 1 (VCAM-1) and E-selectin in cultured human coronary artery endothelial cells (HCAEC). This effect resulted from a rise in intracellular free calcium induced by Lp(a) and could be inhibited by the intracellular calcium chelator, BAPTA/AM. The involvement of the LDL and VLDL receptors in Lp(a) activation of HCAEC were ruled out since Lp(a) induction of adhesion molecules was not prevented by an antibody (IgGC7) to the LDL receptor or by receptor-activating protein, an antagonist of ligand binding to the VLDL receptor. Addition of alpha2-macroglobulin as well as treatment with heparinase, chondroitinase ABC, and sodium chlorate did not decrease levels of VCAM-1 and E-selectin stimulated by Lp(a), suggesting that neither the low density lipoprotein receptor-related protein nor cell-surface proteoglycans are involved in Lp(a)-induced adhesion molecule production. Neither does the binding site on HCAEC responsible for adhesion molecule production by Lp(a) appear to involve plasminogen receptors, as levels of VCAM-1 and E-selectin were not significantly decreased by the addition of glu-plasminogen, the lysine analog epsilon-aminocaproic acid, or by trans-4-(aminomethyl)-cyclohexanecarboxymethylic acid (tranexamic acid), which acts by binding to the lysine binding sites carried on the kringle structures in plasminogen. In contrast, recombinant apolipoprotein (a) [r-apo(a)] competed with Lp(a) and attenuated the expression of VCAM-1 and E-selectin. In summary, we have identified a calcium-dependent interaction of Lp(a) with HCAEC capable of inducing potent surface expression of VCAM-1 and E-selectin that does not appear to involve any of the known potential Lp(a) binding sites. Because leukocyte recruitment to the vessel wall appears to represent one of the important early events in atherogenesis, this newly described endothelial cell-activating effect of Lp(a) places it at a crucial juncture in the initiation of atherogenic disease and may lead to a better understanding of the role of Lp(a) in the vascular biology of atherosclerosis.

An evaluation of nebulized prostacyclin in patients with primary and secondary pulmonary hypertension

AIMS

To investigate the response to inhaled prostacyclin in patients with primary and secondary pulmonary hypertension and to compare its effects to those of intravenous prostacyclin and inhaled nitric oxide.

METHODS AND RESULTS

Twelve patients with pulmonary hypertension (seven primary and five secondary) were studied. All patients had a pulmonary artery balloon flotation catheter inserted into the proximal pulmonary artery and radial arterial line. Prostacyclin was nebulized with 81.min-1 of oxygen and administered in doses increasing from 15 to 50 ng.kg-1.min-1 via a facemask. Eight of these patients also received intravenous prostacyclin in doses of 1 to 5 ng.kg-1.min-1 and nitric oxide in doses of 10 to 100 ppm via a facemask. Haemodynamic measurements were taken during each treatment. In the 12 patients, nebulized prostacyclin produced a significant reduction in mean pulmonary artery pressure from 56 +/- 5 to 45 +/- 4 mmHg (P = 0.0001). The pulmonary vascular resistance decreased by 38% from 964 +/- 169 to 595 +/- 116 dyne.s-1.cm-5 (P = 0.0001). Direct comparison with inhaled nitric oxide and intravenous prostacyclin in eight patients demonstrated that nebulized prostacyclin produced a greater fall in mean pulmonary artery pressure than the other two agents without any significant effect on systemic arterial pressure.

CONCLUSION

Nebulized prostacyclin appears to be more effective at reducing pulmonary artery pressure in patients with pulmonary hypertension when compared to intravenous prostacyclin and inhaled nitric oxide. This could have important clinical implications for the management of patients with pulmonary hypertensions.

Effects of cardiac transplantation on bioenergetic abnormalities of skeletal muscle in congestive heart failure

BACKGROUND

Patients with advanced heart failure have bioenergetic abnormalities of skeletal muscle metabolism during exercise. Using 31P magnetic resonance spectroscopy, we sought to determine whether skeletal metabolic responses to exercise are normalized by orthotopic cardiac transplantation.

METHODS AND RESULTS

Four groups were studied: healthy normal volunteers (n = 9), subjects awaiting heart transplantation (n = 10), subjects < 6 months (mean, 4 months) after transplant (n = 9), and subjects > 6 months (mean, 15 months) after transplant (n = 8). None of the posttransplant patients had biopsy evidence of rejection at the time of study. There were no significant differences in age, preoperative functional class, or symptom duration among the three patient groups. Metabolic responses were monitored in the dominant arm during incremental weight pull exercise and 10 minutes of recovery by 31P magnetic resonance spectroscopy, with measurement of pH and the phosphocreatine (PCr)/(PCr + inorganic phosphate [Pi]) ratio, an index of PCr concentration. In addition, based on recovery data, the rate of PCr resynthesis was calculated as a measure of oxidative metabolism that is independent of work level, recruitment, or muscle mass, and the effective maximal rate of mitochondrial ATP synthesis (Vmax) was determined. Analysis was by ANOVA. There were no differences between groups in pH or PCr/(PCr + Pi) at rest. Compared with the normal control group, the pretransplant group had a decreased exercise duration (11.3 +/- 2.5 versus 15.0 +/- 1.3 minutes, P = .02), a lower submaximal exercise PCr/(PCr + Pi) ratio (0.58 +/- 0.11 versus 0.76 +/- 0.08, P < .05), a reduced PCr resynthesis rate (13 +/- 6 versus 22 +/- 9 mmol/L per minute, P < .05), and a lower calculated Vmax (26 +/- 14 versus 53 +/- 26 mmol/L per minute, P < .05). In the group studied early after transplantation, all the changes noted in the pretransplant group persisted and were if anything somewhat worse. In the group studied late after transplantation, there was a significant improvement in the PCr resynthesis rate compared with the early-posttransplant group (27 +/- 6 late versus 15 +/- 6 mmol/L per minute early, P < .05) and statistically nonsignificant trends toward improvements in submaximal exercise pH (6.86 +/- 0.24 late versus 6.72 +/- 0.24 early) and submaximal PCr/(PCr + Pi) ratio (0.56 +/- 0.14 late versus 0.44 +/- 0.15 early) and Vmax (45 +/- 21 late versus 33 +/- 15 mmol/L per minute early). However, compared with normal subjects, exercise duration and submaximal PCr/(PCr + Pi) were still reduced in the late-posttransplant group.

CONCLUSIONS

Despite successful heart transplantation, skeletal muscle abnormalities of advanced heart failure persist for indefinite periods, although partial improvement occurred at late times. The persistent abnormalities may contribute to the reduced exercise capacity that is present in most patients after transplantation.

Transmission of donor Epstein-Barr virus (EBV) in transplanted organs causes lymphoproliferative disease in EBV-seronegative recipients

Epstein-Barr virus (EBV) is associated with post-transplant lymphoproliferative disease (PTLD). To determine whether the donor EBV isolate is transmitted to the recipient via the allograft and causes PTLD, EBV isolates from four cases of PTLD in cadaveric heart and/or lung transplant recipients were compared with the donor isolates by PCR and DNA sequence analysis. Two recipients who were EBV seronegative at transplantation acquired an EBV isolate indistinguishable from that of the donor and developed PTLD. In contrast, in two patients who were seropositive before transplantation, the donor isolate differed from that present in PTLD of the recipient. The results suggest that the acquisition of donor EBV is a risk factor for PTLD development in a previously seronegative transplant recipient.

Expression of cyclo-oxygenase-2 in human airway smooth muscle is associated with profound reductions in cell growth

1. It is now accepted that uncontrolled proliferation of human airway smooth muscle (HASM) cells contributes, in many cases, to the chronic stages of asthma. However, the physiological and pathophysiological processes regulating cell growth and division in the airway are not clear. We have recently shown that the immediate early gene, cyclo-oxygenase-2, is induced by cytokines in HASM cells. Since cyclo-oxygenase metabolites, such as prostaglandin (PG) E2 have been shown to modulate HASM cell growth, we have investigated any autocrine action of endogenously released cyclo-oxygenase-1/2 products on the proliferative responses in these cells. 2. HASM cells were cultured from healthy tissue obtained at lung or heart/lung transplantation. HASM cell proliferation was measured by [3H]-methyl thymidine uptake by cells and by cell counts. Cyclo-oxygenase-2 expression was measured by Western blot analysis and activity measured by the release of PGE2, by radioimmunoasay. 3. HASM cells proliferated in response to foetal calf serum, a response that was greatly inhibited when cyclo-oxygenase-2 was induced with either interleukin-1beta plus tumour necrosis factor-alpha or interleukin-1beta, tumour necrosis factor alpha plus interferon gamma (each at 10 ng ml(-1)). The inhibitory effect of cytokines on HASM cell proliferation was reversed in a concentration dependent manner by either the mixed cyclo-oxygenase-1/-2 inhibitor, indomethacin or the selective cyclo-oxygenase-2 inhibitor, L-745,337 (each at 10 microM). 4. PGE2 or the stable analogue of prostacyclin, cicaprost concentration-dependently (0.1 pmol to 1 microM) inhibited serum induced proliferation of HASM cells. By contrast, the TP receptor agonist, U46619 stimulated proliferation of HASM cells when cells were cultured without but not with serum. Other cyclo-oxygenase products, PGD2, PGF2alpha had no effect on cellular proliferation at concentrations up to 1 microM. 5. These observations illustrate a profound inhibitory effect of cyclo-oxygenase-2 induction on HASM cell proliferation, possibly via IP or EP receptor activation. Cyclo-oxygenase-2 induction has, thus far, been associated with the pro-inflammatory responses of plasma exudation and oedema formation and is assumed to be an enzyme worthy of selective inhibition in many disease states. However, our observations suggest that cyclo-oxygenase-2 can have an anti-inflammatory, anti-proliferative function in the airways. These observations may have importance in the use and development of therapies for airway disease such as asthma.

Influence of anatomic correction for transposition of the great arteries on myocardial perfusion: radionuclide imaging with technetium-99m 2-methoxy isobutyl isonitrile

OBJECTIVES

We sought to determine the incidence of late perfusion defects attributable to coronary artery mobilization in patients undergoing anatomic correction for complete transposition of the great arteries.

BACKGROUND

Anatomic correction (arterial switch procedure) is currently the surgical treatment of choice for complete transposition. From its conception, there has been concern about the impact on myocardial perfusion of the coronary artery mobilization and reimplantation involved in the correction. Previous studies have demonstrated myocardial perfusion defects in patients after correction, although a causal relation between coronary mobilization, and perfusion abnormality has not been established.

METHODS

In a case-comparison study designed to test this hypothesis, 29 children underwent imaging with technetium-99m 2-methoxy isobutyl isonitrile (technetium-99m mibi). Ten had undergone anatomic correction (arterial switch group; interval from operation 6.9 +/- 1.42 years [range 4.9 to 9.1]); 9 had required noncoronary open heart surgery for other cardiac lesions (post-bypass group; interval from operation 5.6 +/- 3.6 years [range 1.0 to 13.25]); and 10 had had no surgical procedure (control group). The latter group comprised children with atrial or ventricular septal defects who required a radionuclide study for shunt calculation. Planar studies were performed in all 29 children, and additional tomographic acquisition was achieved in 25. To assess reversibility of perfusion defects both an exercise and a rest planar study were performed in the arterial switch group.

RESULTS

Perfusion abnormalities were observed in seven of the nine children in the postbypass group and in all 10 children in the arterial switch group. The frequency of perfusion defects in these two groups was similar, with at least 25% of the tomographic segments reported being abnormal. The control group had significantly fewer defects than the other two groups (p = 0.02), with only 8% of the tomographic segments judged to be abnormal. In all except one patient in the arterial switch group, the segments reported as abnormal on the planar exercise study were either abnormal or equivocal on the rest study, indicating a fixed abnormality.

CONCLUSIONS

Although the precise etiology of these perfusion abnormalities cannot be defined from this study, these data suggest that their origin is related more to the insult of open heart surgery itself than to the coronary manipulation involved in the arterial switch procedure. The functional importance requires further study.

The clinical outcome of off-pump coronary artery bypass surgery in the elderly patients

OBJECTIVE

There has been a body of evidence showing that off-pump coronary artery bypass (OPCAB) may reduce morbidity and mortality in the elderly patients. We reviewed our experience, retrospectively, on elderly patients aged 75 years and older who were operated on using the OPCAB technique. We compared their outcome to a similar group of elderly patients who were operated on using conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) during the same period of time.

METHODS

Registry data and patients' notes and charts were reviewed for 56 consecutive elderly OPCAB patients (age 78.5+/-3.5 years) and 87 consecutive CPB patients (age 77.2+/-2.4 years, P=0.01). Both groups had similar risk factor profiles: Parsonnet score 17.4+/-4.4 (OPCAB) versus 16.6+/-5.2 (CPB), P=0.19. We studied in detail their preoperative and postoperative data in order to compare the outcomes of both techniques.

RESULTS

The length of stay in the intensive therapy unit (ITU) was 35.4+/-52.9h for OPCAB patients and 77.6+/-144.9h for CPB patients (P=0.0008). No patient died within 30 days in the OPCAB group, whilst ten (11%) CPB patients (P=0.0066) died within 30 days. The incidence of serious complications (including pulmonary oedema, septicaemia, permanent stroke and renal dysfunction requiring haemofiltration or haemodialysis) was one (2%) in the OPCAB group and 11 (13%) in the CPB group (P=0.028). CPB patients required a significantly higher number ten (12%) of intra-aortic balloon pumps (IABP) inserted compared to only one patient (2%) in the OPCAB group who required IABP insertion (P=0.05). Nine (11%) CPB patients were re-operated on for bleeding compared to no OPCAB patient (0%) needing re-operation, P=0.011.

CONCLUSIONS

Although the mean age of the OPCAB group was significantly higher than the CPB group, the OPCAB group showed a significant reduction in postoperative serious morbidity, ITU stay and mortality. We believe that such a conclusion may have some effect on the decision-making and cost-effectiveness when performing coronary bypass surgery on the elderly population.

Nitric oxide synthase activity is elevated in inflammatory lung disease in humans

We have characterised nitric oxide (NO) synthase activity in lung samples from patients with inflammatory lung disease compared to that in normal donor lung. NO synthase activity was measured by the ability of tissue homogenates to convert L-arginine to L-citrulline. Higher levels of NO synthase activity were found in samples from patients with inflammatory lung disease (mild asthma, cystic fibrosis, obliterative bronchiolitis after lung transplantation) compared to samples from healthy donors. NO synthase activity in all samples was mainly dependent on the presence of extracellular Ca2+. The increased NO synthase activity in diseased-lung samples suggests a modulatory role for nitric oxide in lung inflammation.