Clinical and pathologic manifestations of pulmonary vascular disease in the toxic oil syndrome

Chemical exposure-induced systemic fibrosing disorders: Novel insights into systemic sclerosis etiology and pathogenesis

Numerous drugs and chemical substances are capable of inducing exaggerated tissue fibrotic responses. The vast majority of these agents cause localized fibrotic tissue reactions or fibrosis confined to specific organs. Although much less frequent, chemically-induced systemic fibrotic disorders have been described, sometimes occurring as temporally confined outbreaks. These include the Toxic Oil Syndrome (TOS), the Eosinophilia-Myalgia Syndrome (EMS), and Nephrogenic Systemic Fibrosis (NSF). Although each of these disorders displays some unique characteristics, they all share crucial features with Systemic Sclerosis (SSc), the prototypic idiopathic systemic fibrotic disease, including vasculopathy, chronic inflammatory cell infiltration of affected tissues, and cutaneous and visceral tissue fibrosis. The study of the mechanisms and molecular alterations involved in the development of the chemically-induced systemic fibrotic disorders has provided valuable clues that may allow elucidation of SSc etiology and pathogenesis. Here, we review relevant aspects of the TOS, EMS, and NSF epidemic outbreaks of chemically-induced systemic fibrosing disorders that provide strong support to the hypothesis that SSc is caused by a toxic or biological agent that following its internalization by endothelial cells induces in genetically predisposed individuals a series of molecular alterations that result in the development of SSc clinical and pathological alterations.

Pulmonary hypertension: From an orphan disease to a global epidemic

[No abstract. Showing first paragraph of article]Pulmonary hypertension is a progressive disease characterized by an elevation of pulmonary artery pressure and pulmonary vascular resistance, leading to right ventricular failure and death. It remains a challenging chronic progressive disease, but the current interest and advent of medical therapy in the last 20 years has significantly changed the perception of medical community in this disease. Pulmonary hypertension is not a specific disease; the majority of cases present with other diseases and various pathological processes that affect the pulmonary vasculature, and consequently increase pulmonary pressure and vascular resistance.

Pulmonary arterial hypertension: new insights into the optimal role of current and emerging prostacyclin therapies

Pulmonary arterial hypertension (PAH), which is a subset of pulmonary hypertension, is a group of diseases distinguished by vascular remodeling of the small pulmonary arteries with associated elevated pulmonary arterial pressure and right ventricular failure. This progressive and sometimes fatal disease occurs as an idiopathic disease or as a component of other disease states. Estimates of the incidence of PAH have varied from 5 to 52 cases/1 million population. Symptoms begin with shortness of breath with exertion and progress to dyspnea with normal activities and, finally, dyspnea at rest. Untreated patients with PAH have a 1-, 3-, and 5-year survival rate of 68%, 48%, and 34%, respectively. Treated, the survival rates improve to 91% to 97% after 1 year and 84% to 91% after 2 years. The current definition of PAH consists of 3 specific hemodynamic assessments confirmed by right heart catheterization findings. One of several important pathophysiologic mechanisms involved in PAH is pulmonary vascular remodeling, which is caused by endothelial and smooth muscle cell hyperproliferation. This is coincident with overexpression of the vasoconstrictor endothelin-1 and a reduction in the vasodilators nitric oxide and prostacyclin, which further impedes proper vasomotor tone, among other effects. Prostacyclin therapies augment the decreased prostacyclin levels in patients with PAH. The currently approved prostacyclins for the treatment of PAH include epoprostenol, iloprost, and treprostinil. Among the 3 medications, the delivery options include intravenous infusion, subcutaneous infusion, and inhaled formulations. Epoprostenol has been shown to have a positive effect on survival in patients with PAH. All prostacyclins have demonstrated improvements in functional class, exercise tolerance, and hemodynamics in patients with PAH. Intravenously and subcutaneously administered formulations of prostacyclins require continuous infusion pump administration, which presents clinical challenges for both the patient and the care provider. Dosing must be individualized and also presents a clinical challenge. Inhaled formulations seem efficacious in moderately symptomatic patients with PAH and might be appropriate when combined with an oral medication. Combination therapies are commonly used in clinical practice, with the decision to do so based on randomized controlled trial data and case study evidence. The present report provides an overview of PAH, the scientific rationale for treatment with prostacyclin therapy, and the benefits and risks of prostacyclin therapy, both as monotherapy and combined with other medications approved for the treatment of PAH.

Pulmonary arterial hypertension

Pulmonary hypertension is a complex and multidisciplinary disorder. The classification of pulmonary hypertension includes 5 groups. Pulmonary arterial hypertension is a rare disorder that can be idiopathic or heritable in nature, or associated with other conditions, such as scleroderma or congenital heart disease. The recent decades have realized advances in the treatment of this once devastating disease. More commonly, pulmonary hypertension is associated with other disorders, such as those that elevate left heart filling pressures and hypoxemic lung disease. Chronic thromboembolic disease can result in pulmonary hypertension. To determine the etiology, a thorough and methodical evaluation must be completed. Often, an echocardiogram is the first test to suggest the diagnosis of pulmonary hypertension. Studies to identify potential associated causes are important. The diagnostic evaluation culminates in right heart catheterization. Over recent years, advances in therapies, including the prostacyclins, the endothelin receptor antagonists, and the phosphodiesterase type 5 inhibitors, have resulted in an improved quality of life and outlook for patients with what is often a progressive disease.

Pulmonary Vascular Disease

The pulmonary vasculature is an anatomic compartment that is frequently overlooked in the histologic review of lung biopsy samples, other than those obtained specifically to assess pulmonary vascular disease.1 Though often of a nonspecific nature, the histologic pattern of vascular remodeling may at times suggest its underlying pathogenesis and provide clues to the cause of pulmonary hypertension.2 Disproportionately severe vascular pathology may further indicate alternate disease processes, such as congestive heart failure or thromboemboli, contributing to the patient’s overall respiratory condition.

Hipertensión pulmonar con el ejercicio en el síndrome del aceite tóxico

BACKGROUND AND OBJECTIVE

Toxic oil syndrome is a risk factor for pulmonary arterial hypertension (PAH) and new cases of this entity are emerging after more than 20 years since the initial toxic oil epidemic. Abnormal elevation of pulmonary systolic pressure with exercise may be considered an early marker of PAH in populations at risk. We aimed to analyze the pulmonary systolic pressure with exercise echocardiography in toxic oil syndrome patients.

PATIENTS AND METHOD

50 toxic oil syndrome patients (cases), and 20 healthy control subjects were submitted to rest and peak exercise echocardiography (semi supine cycloergometer) measuring pulmonary systolic pressure. In toxic oil syndrome patients, pulmonary carbon monoxide diffusion capacity was also analyzed.

RESULTS

Peak exercise pulmonary systolic pressure was statistically similar in cases and controls. Nevertheless, 8% of cases reached a pulmonary systolic pressure > or = 80 mmHg and this fact was associated with mild pulmonary arterial hypertension, reduced right ventricular function and abnormal pulmonary diffusion capacity in the rest study. A rest pulmonary systolic pressure cut-off value > or = 27 mmHg had a 100% sensitivity and 71% specificity to predict a peak exercise systolic pulmonary pressure > or = 80 mmHg.

CONCLUSIONS

A minority of toxic oil syndrome patients develop severe pulmonary arterial hypertension during exercise. This abnormal response is associated with other markers of pulmonary vasculopathy. Further studies are needed to elucidate the relation between these findings and the likelihood to develop pulmonary arterial hypertension in the future.

[Lung function testing in patients with pulmonary arterial hypertension]

OBJECTIVE

The main objective was to describe the results of lung function testing in a series of 120 patients with pulmonary arterial hypertension, and the secondary objective was to compare these findings with hemodynamic variables.

PATIENTS AND METHODS

This was a descriptive study of lung function in 120 patients with stable pulmonary arterial hypertension (Evian/Venice groups 1 and 4) studied until January 2002 in the Pulmonary Hypertension and Lung Transplant Working Group attached to the Cardiology Department of the Hospital Universtario 12 de Octubre in Madrid, Spain. Data were collected retrospectively for the first 47 patients (1981 to 1995) and prospectively thereafter for the remaining 73 patients. The diagnosis was idiopathic arterial hypertension or hypertension associated with collagenosis, chronic pulmonary embolism, cardiac shunt, or toxic oil syndrome (30 cases).

RESULTS

In the group as a whole, forced vital capacity, forced expiratory volume in 1 second, and total lung capacity were normal; mean (SD) values revealed low carbon dioxide diffusing capacity (67.6% [23.2%]), and moderate hypoxemia (65.8 [15.4] mm Hg). No significant associations were observed between lung function and hemodynamic parameters. Mean age in the toxic oil syndrome group was lower (33.7 [11.4] years), and these patients had higher mean scores on the New York Heart Association scale (3.3 [0.5]) and for pulmonary vascular resistance (20.3 [8.1] kPa.L(-1).s).

CONCLUSIONS

Lung function was studied in a series of 120 patients with pulmonary arterial hypertension (Evian/ Venice groups 1 and 4), 30 of whom had toxic oil syndrome. No significant associations were found between lung function and hemodynamic parameters.

Pulmonary hypertension in autoimmune rheumatic diseases

Arterial pulmonary hypertension (PH) might be a complication of some autoimmune rheumatic diseases, specially systemic sclerosis. This form of arterial PH is indistinguishable from primary PH, characterised by the presence of plexiform lesions. Although for many years plexiform lesions have been considered end-stage scarring lesions, they are composed by actively proliferating endothelial cells that share many features with cancer cells. Endothelial cells within plexiform lesions in all forms of arterial PH show a decrease in the expression of vasodilator and anti-proliferative factors, and an increase in the expression of vasoconstrictor and angiogenic and mitogenic factors. These cells also show important alterations in growth and apoptosis key regulatory genes. Plexiform lesions are surrounded by inflammatory cell infiltrates, probably providing cytokines that may contribute to the endothelial cell proliferative process. All these data suggest that arterial PH might be seen as a proliferative endothelial cell process, which would open new therapeutic approaches for this devastating disease.

Screening, early detection, and diagnosis of pulmonary arterial hypertension: ACCP evidence-based clinical practice guidelines

Pulmonary arterial hypertension (PAH) occurs as an idiopathic process or as a component of a variety of disease processes, including chronic thromboembolic disease, connective tissue diseases, congenital heart disease, and exposure to exogenous factors including appetite suppressants or infectious agents such as HIV. This article reviews evidence for screening in susceptible patient groups and the approach to diagnosing PAH when it is suspected, and provides specific recommendations for applying this evidence to clinical practice.

Gender issues in pulmonary vascular disease

Gender differences in pulmonary vascular diseases, as exemplified by primary pulmonary hypertension and scleroderma-related pulmonary hypertension, are not well-explained; however, in general terms, they seem to be related to a combination of genetic predispositions and gender-specific environmental triggers. More information is needed in both areas with respect to mechanisms of disease. More information also is needed about possible gender differences in disease presentation,course, and response to treatments.

Pulmonary arterial hypertension in children

Pulmonary arterial hypertension is a serious progressive condition with a poor prognosis if not identified and treated early. Because the symptoms are nonspecific and the physical findings can be subtle, the disease is often diagnosed in its later stages. Remarkable progress has been made in the field of pulmonary arterial hypertension over the past several decades. The pathology is now better defined, and significant advances have occurred in understanding the pathobiologic mechanisms. Risk factors have been identified, and the genetics have been characterized. Advances in technology allow earlier diagnosis as well as better assessment of disease severity. Therapeutic modalities such as new drugs, e.g., epoprostenol, treprostinil, and bosentan, and surgical/interventional options, e.g., transplantation and atrial septostomy, which were unavailable several decades ago, have had a significant impact on prognosis and outcome. Thus, despite our inability to cure pulmonary arterial hypertension, advances in medical treatments over the past two decades have resulted in significant improvement in outcomes for children with various forms of pulmonary arterial hypertension. This report is a review the current state of the art for pulmonary arterial hypertension in 2004, with an emphasis on childhood pulmonary arterial hypertension and specific recommendations for current practice and future directions.

[Diagnostic performance of echocardiography in the follow-up of patients with toxic oil syndrome]

INTRODUCTION AND OBJECTIVES

Toxic oil syndrome is an epidemic, multisystemic disease that appeared in Spain in 1981, and was caused by the consumption of rapeseed oil denatured with 2% aniline. The disease is similar to eosinophilia-myalgia syndrome. One of the cardiovascular disorders caused by this syndrome is pulmonary hypertension. We conducted a study to assess the validity of our indications for echocardiography in the follow-up of cardiovascular disorders in patients with this disease.

PATIENTS AND METHOD

These patients are followed at our center with a standardized protocol for annual check-ups. From December 1997 through July 2002, a total of 1993 patients were examined. In this period we performed a total of 487 echocardiographic studies in 424 patients. The clinical records were reviewed to assess the indications for echocardiography according to the most recent guidelines for the clinical application of echocardiography of the American College of Cardiology and American Heart Association, and the indications were grouped into several categories. The diagnosis was recorded from the cardiologist's reports at the hospital where echocardiography was done. We calculated the sensitivity, specificity and positive likelihood ratio.

RESULTS

67% of the echocardiographic examinations were indicated to investigate possible pulmonary hypertension. About one-tenth of the studies (476 studies, 9.9%) led to a diagnosis of pulmonary hypertension. Sensitivity was highest (83%) for suspected pulmonary hypertension. Specificity was very high for most of the other indications.

CONCLUSIONS

This study does not allow us to draw general conclusions about the cardiovascular disorders associated with toxic oil syndrome. However, echocardiography appears to be a good follow-up technique to diagnose complications such as pulmonary hypertension in these patients.

Insights into the genetic and molecular basis of primary pulmonary hypertension

The pathogenesis of primary pulmonary hypertension (PPH) remains poorly understood. Molecular genetic studies have identified that mutations within the gene BMPR2 on the long arm of chromosome 2 underlie familial PPH. This review explores the significance of the PPH gene identification and examines additional genetic determinants, emphasizing the immediate implications for assessment and management of patients and their relatives.

[Ten years' experience in continuous intravenous epoprostenol therapy in severe pulmonary arterial hypertension]

INTRODUCTION

Primary pulmonary hypertension and its associated forms is a progressive and often fatal disease, the course of which has been favourably modified by prostacyclin therapy in the last decade.

OBJECTIVE

The aim of this study is to analize retrospectively the efficacy of continuous intravenous epoprostenol (synthetic prostacyclin) therapy in pulmonary arterial hypertension, and to compare it with conventional therapy (anticoagulants, digoxin and diuretics).

METHODS

Between 1990-2000, 31 patients with severe precapillary pulmonary hypertension in functional class III or IV went on continuous intravenous epoprostenol therapy, administered by a portable infusion pump through a Hickman catheter. We compared their survival with a group of 16 patients treated with conventional therapy alone.

RESULTS

Time of follow-up was 33.25 months in the prostacyclin group and 20 months in the conventional group. The one- three- and five- year survival rates were 86%, 50% and 38% respectively for patients treated with epoprostenol compared with 40%, 40% and 8% survival rates at idetical periods for patients treated conventionally (p = 0,02). Functional class and the mean distance walked in the 6 minutes test were improved in patients treated with prostacyclin (p < 0,01). Serious complications attributable to the delivery system included 3 deaths, mainly due to infection.

CONCLUSION

Continuous intravenous epoprostenol therapy improves survival and exercise capacity in patients with severe pulmonary arterial hypertension despite potentially serious complications attributable to the delivery system.

Current management of primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare disorder of the lung vasculature characterised by an increase in pulmonary artery pressure. Although the aetiology of this disease remains unknown, knowledge of the pathophysiology of the disease has advanced considerably. Diagnosis of PPH is largely by exclusion. The clinical symptoms associated with PPH are aspecific and similar to those seen in other cardiovascular and pulmonary diseases. Electrocardiography, echocardiography, pulmonary function tests, and a lung perfusion scan are necessary to exclude secondary forms of pulmonary hypertension and also help to confirm the diagnosis of PPH. A definite diagnosis of PPH is established by right-heart catheterisation which gives a precise measure of the blood pressure in the right side of the heart and the pulmonary artery, right ventricular function and cardiac output. Once a diagnosis of PPH is established, treatment involving drug therapy or surgery is commenced on the basis of the New York Heart Association functional class. Conventional treatment consists of lifetime administration of anticoagulants, oxygen, diuretics, and digoxin. Vasodilator therapy with calcium channel antagonists is indicated in patients who are 'vasoreactive' to acute vasodilator challenge as assessed by right-heart catheterisation. Promising results are obtained by continuous intravenous administration of epoprostenol (prostacyclin). Newer therapies for PPH include prostacyclin analogues, endothelin receptor antagonists, nitric oxide, phosphodiesterase-5 inhibitors, elastase inhibitors, and gene therapy. Surgical treatment consists of atrial septostomy, thromboendarterectomy, and lung or heart-lung transplantation.

BMPR2 haploinsufficiency as the inherited molecular mechanism for primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a potentially lethal disorder, because the elevation of the pulmonary arterial pressure may result in right-heart failure. Histologically, the disorder is characterized by proliferation of pulmonary-artery smooth muscle and endothelial cells, by intimal hyperplasia, and by in situ thrombus formation. Heterozygous mutations within the bone morphogenetic protein type II receptor (BMPR-II) gene (BMPR2), of the transforming growth factor beta (TGF-beta) cell-signaling superfamily, have been identified in familial and sporadic cases of PPH. We report the molecular spectrum of BMPR2 mutations in 47 additional families with PPH and in three patients with sporadic PPH. Among the cohort of patients, we have identified 22 novel mutations, including 4 partial deletions, distributed throughout the BMPR2 gene. The majority (58%) of mutations are predicted to lead to a premature termination codon. We have also investigated the functional impact and genotype-phenotype relationships, to elucidate the mechanisms contributing to pathogenesis of this important vascular disease. In vitro expression analysis demonstrated loss of BMPR-II function for a number of the identified mutations. These data support the suggestion that haploinsufficiency represents the common molecular mechanism in PPH. Marked variability of the age at onset of disease was observed both within and between families. Taken together, these studies illustrate the considerable heterogeneity of BMPR2 mutations that cause PPH, and they strongly suggest that additional factors, genetic and/or environmental, may be required for the development of the clinical phenotype.

Primary pulmonary hypertension: the pressure rises for a gene

Primary pulmonary hypertension (PPH) represents the end stage of a disruption of pulmonary vascular integrity, of unknown cause. Although PPH is associated with several systemic disorders, there have hitherto been few clues as to the aetiological factors responsible for the pathogenesis of this condition. As an example of the application of modern molecular genetics and positional cloning, this leader describes the range of studies currently under way, which aim to find the gene that underlies PPH, and summarises the implications of the identification of such a gene.

Primary pulmonary hypertension: a vascular biology and translational research "Work in progress"

Primary pulmonary hypertension (PPH) is a syndrome of dyspnea, chest pain, and syncope defined by increased pulmonary vascular resistance and the absence of a known cause. It also occurs in a familial form, which is linked to unidentified genes on chromosome 2. This syndrome is characterized by abnormalities of pulmonary vascular biology in each compartment of the blood vessel. The lumen has a prothrombotic diathesis, the endothelium displays an excessive production of vasoconstrictors relative to vasodilators, and the smooth muscle cells are depolarized and calcium-overloaded, which is due in part to reduced expression of voltage-gated potassium channels (Kv). This causes vasoconstriction and may promote cell proliferation. The adventitia displays excessive remodeling, which is associated with exaggerated metalloproteinase and elastase activity. Conceptually, PPH seems to require a permissive genotype, a susceptible phenotype (eg, endothelial dysfunction) and, in many cases, an exogenous trigger (eg, an anorexigen). Although there is not a generally accepted, unifying hypothesis regarding its cause, impaired function and the expression of vascular and platelet Kv channels suggest PPH may be a disease of the ion channels. Abnormal matrix metalloproteinase and elastase activity could also explain the abnormal vascular tone, platelet activation, and remodeling in PPH. Although calcium-channel blockers and prostacyclin, particularly when coadministered with warfarin, improve survival, PPH has a 5-year mortality rate of approximately 50%. Pharmacological and gene therapies aimed at enhancing the activity of prostacyclin, nitric oxide synthases, and Kv channels or at inhibiting endothelin and matrix metalloproteinases are promising areas for future development.

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.

Obesity drugs and the heart

Appetite suppressant-related pulmonary hypertension and valvular heart disease are established disorders. Currently, the mechanism of these disorders is not certain. An estimated 6 million Americans and 70 million persons worldwide have been exposed to fenfluramine and dexfenfluramine. The clinical significance and long-term prognosis of cardiovascular effects and, thus, the potential public health effect of these disorders are not known. Longitudinal studies are required to further evaluate these disease processes. In addition, although isolated cases of regression of pulmonary hypertension and valve disease have been reported after the cessation of appetite suppressant therapy, the natural history remains uncertain.

Tricuspid valve disease. Clinical evaluation, physiopathology, and management

The tricuspid and mitral valves are homologous whose function depends on coordination among components. Isolated tricuspid valve abnormalities are relatively uncommon. Rheumatic disease, chemicals, immunologic and degenerative disorders alter leaflet anatomy and may result in either stenosis, insufficiency or a combination. More often, tricuspid disorders present as a component of congenital syndromes or secondary to pulmonary vascular or let heart disease which alter geometry and function of nonleaflet components.

Percutaneous pulmonary endoarterial biopsy in an experimental model of pulmonary hypertension

STUDY OBJECTIVES

The aims of this study were: to evaluate the performance of a novel arterial biopsy catheter in obtaining pulmonary endovascular samples in hypertensive dogs; to compare the results of pulmonary endoarterial biopsy in hypertensive vs normotensive dogs; and to assess the histologic changes in the hypertensive model.

DESIGN AND INTERVENTIONS

Thirty-four dogs (27 with normal pulmonary arterial pressures and seven with pulmonary hypertension) were catheterized through an external jugular vein to obtain endovascular biopsy samples from distal pulmonary arteries 2 to 3 mm in luminal diameter. To induce pulmonary hypertension, seven dogs were given repeated infusions of 0.6- to 0.9-mm ceramic microspheres into the superior vena cava. Endoarterial samples were obtained at pulmonary systolic arterial pressures ranging from 10 to 110 mm Hg.

MEASUREMENTS AND RESULTS

Sixty-two biopsy catheterization procedures were performed in the 34 dogs. After 12 initial procedures of technique refinement, endoarterial samples were obtained in each of the last 50 procedures (21 in normotensive dogs and 29 in hypertensive dogs). The average number of endovascular biopsy samples retrieved was 7.1 (range, 2 to 12) from a mean of 8.6 (range, 2 to 15) biopsy attempts per catheterization (success rate=83%). The average biopsy piece measured 1.13 mm in length, 0.33 mm in depth, and up to 1.0 mm in width. The biopsy success rates and endoarterial sample sizes were similar in normotensive and hypertensive dogs. Smooth muscle cells and endothelial cells were grown from the biopsy samples. There were no significant procedural complications, except for one self-limited hemorrhage. Histologically, samples obtained from dogs with pulmonary hypertension showed characteristic changes when compared with biopsies from normotensive dogs.

CONCLUSION

This new endoarterial biopsy catheter was safe and effective when used to obtain pulmonary endoarterial samples in dogs with normal and experimentally elevated pulmonary arterial pressures. The quality and quantity of the biopsy samples allowed identification of pathologic changes.

Cytokine mRNA expression in lung tissue from toxic oil syndrome patients: a TH2 immunological mechanism

In 1981, an epidemic occurred in Spain, toxic oil syndrome (TOS), in people who consumed rapeseed oil denatured with 2% aniline, and it was one of the largest intoxication epidemics ever recorded. In 1989, a similar disease, eosinophilia-myalgia syndrome (EMS) was reported in the USA and was associated with the ingestion of L-tryptophan. The pathologic findings in TOS showed primary endothelial injury, with cell proliferation and perivascular inflammatory infiltrates. Immunologic mechanisms have presumably been operative in the pathogenesis and perpetuation of TOS. Our previous findings pointed to a T-cell activation during acute phase of the disease. In order to analyze which T-cell subset is involved on TOS, we have developed an mRNA extraction procedure from paraffin-embedded lung tissues in patients with pulmonary involvement. We analyzed mRNA expression from different cytokines (IL-1, IL-2, IL-4, IL-5, IFN-gamma, GM-CSF) and CD25 (interleukin 2 receptor) and CD23 (low affinity IgE receptor), using RT-PCR technique. In lung tissues from these patients a T-cell activation was observed. We found a significant increase in Th1 (P = 0.006) and Th2 (P = 0.003) cytokine profile in TOS patients with respect to controls. The increment in TH2 response with respect to TH1 is significant (P = 0.03) in TOS lung specimens. Non-significant differences were obtained in other cytokines and receptors studied as IL-1, CD25, CD23 and GM-CSF. Data presented in this paper are the first clear evidence that an immunological mechanism is directly implicated in this illness.

Anorexic agents aminorex, fenfluramine, and dexfenfluramine inhibit potassium current in rat pulmonary vascular smooth muscle and cause pulmonary vasoconstriction

BACKGROUND

The appetite suppressant aminorex fumarate is thought to have caused an epidemic of pulmonary hypertension in Europe in the 1960s. More recently, pulmonary hypertension has been described in some patients taking other amphetamine-like, anorexic agents: fenfluramine and its d-isomer, dexfenfluramine. No mechanism has been demonstrated that might account for the association between anorexic drugs and pulmonary hypertension.

METHODS AND RESULTS

Using the whole-cell, patch-clamp technique, we found that aminorex, fenfluramine, and dexfenfluramine inhibit potassium current in smooth muscle cells taken from the small resistance pulmonary arteries of the rat lung. Dexfenfluramine causes reversible membrane depolarization in these cells. These actions are similar to those of hypoxia, which initiates pulmonary vasoconstriction by inhibiting a potassium current in pulmonary vascular smooth muscle. In the isolated, perfused rat lung, aminorex, fenfluramine, and dexfenfluramine induce a dose-related increase in perfusion pressure. When the production of endogenous NO is inhibited by N-nitro-L-arginine methyl ester, the pressor response to dexfenfluramine is greatly enhanced.

CONCLUSIONS

These observations indicate that anorexic agents, like hypoxia, can inhibit potassium current, cause membrane depolarization, and stimulate pulmonary vasoconstriction. They suggest one mechanism that could be responsible for initiating pulmonary hypertension in susceptible individuals. It is possible that susceptibility is the result of the reduced production of an endogenous vasodilator, such as NO, but this remains speculative.

The toxic oil syndrome

Hundreds died and thousands were poisoned by rapeseed oil adulterated with aniline and sold illegally in Spain in 1981. The clinical manifestations, now known as the toxic oil syndrome, include pulmonary hypertension and right ventricular hypertrophy plus widespread vascular and neural lesions in other organs. Many of the late deaths ended with a scleroderma-like illness. Because scleroderma involves the heart, an examination was made of the small and large coronary arteries, the neural structures, and the conduction system from 11 victims dying with the toxic oil syndrome. Dense fibrosis, atrionodal junctional hemorrhages, and cystic degeneration of the sinus nodes were present. Small and large coronary arteries exhibited focal fibromuscular dysplasia and a proliferative cystic myointimal degeneration. This latter abnormality was associated with sloughing of the inner wall and embolization of the detached fragment downstream in the same coronary artery. Every heart had many degenerative lesions within nerves, ganglia, and the coronary chemoreceptor. Based upon observations by others with experimental feeding of rapeseed oil containing either high or low erucic acid, it is suggested that this oil must remain a major suspected cause of the toxic oil syndrome, particularly in conjunction with some as yet unexplained facilitative influence by oleoanilids. If this is so, it is important to reexamine the widely recommended use of any rapeseed oil product as a suitable food for humans or animals.

Cardiac abnormalities in the toxic oil syndrome, with comparative observations on the eosinophilia-myalgia syndrome

Early in the course of studies of the Spanish toxic oil syndrome it was recognized that vascular lesions were a major problem, most logically attributable to endothelial damage by the toxic oil. However, most clinical attention has been directed to the pulmonary complications and the evolution into a scleroderma-like illness later. In this study of 11 victims of the toxic oil syndrome careful postmortem studies of the coronary arteries and conduction system and neural structures of the heart demonstrated major injury to all those components of the heart. Obliterative fibrosis of the sinus node in four cases resembled findings in fatal scleroderma heart disease, and in eight the cardiac lesions resembled those of lupus erythematosus. The more impressive pathologic features involved the coronary arteries and neural structures, which were abnormal in every heart. The arterial disease included widespread focal fibromuscular dysplasia, but there was also an unusual myointimal proliferative degeneration of both small and large coronary arteries in five patients, four of whom were young women. In two hearts, portions of the inner wall of the sinus node artery had actually detached and embolized downstream. Coronary arteritis was rarely found. Inflammatory and noninflammatory degeneration of cardiac nerves was widespread. Fatty infiltration, fibrosis and degeneration were present in the coronary chemoreceptor. In most respects these cardiac abnormalities resemble those described in the eosinophilia-myalgia syndrome caused by an altered form of L-tryptophan. In both diseases there is good reason to anticipate more clinical cardiac difficulties than have so far been reported, and even more basis for future concern, especially relative to coronary disease and cardiac electrical instability.