Human angiopoietin gene expression is a marker for severity of pulmonary hypertension in patients undergoing pulmonary thromboendarterectomy.

OBJECTIVE: A consistent pathologic feature seen in lungs of patients with pulmonary hypertension from thromboembolic disease is hyperplasia of the media of pulmonary arterioles. The molecular factors responsible for these vessel wall changes are unknown. Angiopoietin-1 is a gene responsible for the formation of the media of blood vessels in utero. We hypothesized that aberrant expression of the angiopoietin-1 gene in the adult lung would be a major contributing factor in the development of pulmonary hypertension. METHODS: From April 1999 to March 2000, a total of 35 patients (18 men, 17 women, mean age 52 years) with pulmonary hypertension and pulmonary vascular resistance ranging from 407 to 2006 dynes x sec x cm(-5) underwent pulmonary endarterectomy at our institution. Before cardiopulmonary bypass, lung biopsy specimens were taken from each patient. Biopsy specimens were also obtained from 10 patients (5 women, 5 men, mean age 55 years) undergoing lung resection for causes other than pulmonary hypertension. All specimens were blindly scored by a pathologist for degree of medial hyperplasia. Quantitative reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry were used to quantitate angiopoietin-1 messenger RNA and protein in each sample. RESULTS: Lung specimens from all patients with pulmonary hypertension demonstrated up-regulation of angiopoietin-1 at the messenger RNA level. The degree of angiopoietin-1 transcription was directly proportional to the preoperative pulmonary vascular resistance and medial wall hyperplasia/hypertrophy in each patient. By immunohistochemistry, angiopoietin-1 protein was confined to the media of pulmonary arterioles. Lung biopsy specimens from patients without pulmonary hypertension had no detectable expression of angiopoietin-1 at the messenger RNA or protein level. CONCLUSION: Angiopoietin-1, a gene responsible for vessel development in the embryonic lung, is up-regulated in the lung parenchyma of patients with pulmonary hypertension. The level of expression of angiopoietin-1 at messenger RNA and protein levels correlates to the severity of pulmonary hypertension in patients with thromboembolic disease and serves as a target for strategies to treat this disease.

Assessment of myocardial postreperfusion viability by intravenous myocardial contrast echocardiography: analysis of the intensity and texture of opacification.

BACKGROUND: Although defects on intracoronary myocardial contrast echocardiography (MCE) indicate loss of viability after reperfusion, opacified segments may also exhibit persistent dyssynergy. Therefore, we related the intensity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissue by postreperfusion MCE. METHODS AND RESULTS: MCE was performed by intravenous injection of 0.15 mL/kg QW7437 in 14 dogs who underwent 3-hour coronary occlusion followed by 3-hour reperfusion. At baseline and 3 hours after reperfusion, midventricular short-axis images were digitized and segmented. Infarction fraction (IF) for each segment was determined by triphenyltetrazolium chloride stain. Of 224 segments, 140 showed no or small infarction and served as a control group. Of 84 segments with significant infarction (IF>30%), 52 exhibited a defect on MCE, and 32 exhibited no defect. Echo texture was quantified by computing entropy based on the co-occurrence matrix analysis of gray-level pairs within each segment. Three hours after reperfusion, average and maximal entropies in the infarct segments without opacification defects were significantly higher than control levels. Histologically, the degree of intracapillary erythrocyte stasis was less in this group than in the infarcted segments with MCE defects with similar magnitude of tissue injuries. CONCLUSIONS: Opacification defects by MCE may be present or absent in myocardium with histologically confirmed infarction. The texture of MCE from opacified but infarcted myocardium differed significantly from control segments and may assist in determination of segmental viability after reperfusion.

Nerve sprouting and sudden cardiac death.

The factors that contribute to the occurrence of sudden cardiac death (SCD) in patients with chronic myocardial infarction (MI) are not entirely clear. The present study tests the hypothesis that augmented sympathetic nerve regeneration (nerve sprouting) increases the probability of ventricular tachycardia (VT), ventricular fibrillation (VF), and SCD in chronic MI. In dogs with MI and complete atrioventricular (AV) block, we induced cardiac sympathetic nerve sprouting by infusing nerve growth factor (NGF) to the left stellate ganglion (experimental group, n=9). Another 6 dogs with MI and complete AV block but without NGF infusion served as controls (n=6). Immunocytochemical staining revealed a greater magnitude of sympathetic nerve sprouting in the experimental group than in the control group. After MI, all dogs showed spontaneous VT that persisted for 5.8+/-2.0 days (phase 1 VT). Spontaneous VT reappeared 13.1+/-6.0 days after surgery (phase 2 VT). The frequency of phase 2 VT was 10-fold higher in the experimental group (2.0+/-2.0/d) than in the control group (0.2+/-0.2/d, P<0.05). Four dogs in the experimental group but none in the control group died suddenly of spontaneous VF. We conclude that MI results in sympathetic nerve sprouting. NGF infusion to the left stellate ganglion in dogs with chronic MI and AV block augments sympathetic nerve sprouting and creates a high-yield model of spontaneous VT, VF, and SCD. The magnitude of sympathetic nerve sprouting may be an important determinant of SCD in chronic MI.

Relationship between regional cardiac hyperinnervation and ventricular arrhythmia.

BACKGROUND: Sympathetic nerve activity is known to be important in ventricular arrhythmogenesis, but there is little information on the relation between the distribution of cardiac sympathetic nerves and the occurrence of spontaneous ventricular arrhythmias in humans. METHODS AND RESULTS: We studied 53 native hearts of transplant recipients, 5 hearts obtained at autopsy of patients who died of noncardiac causes, and 7 ventricular tissues that had been surgically resected from the origin of ventricular tachycardia. The history was reviewed to determine the presence (group 1A) or absence (group 1B) of spontaneous ventricular arrhythmias. Immunocytochemical staining for S100 protein, neurofilament protein, tyrosine hydroxylase, and protein gene product 9.5 was performed to study the distribution and the density of sympathetic nerves. The average left ventricular ejection fraction was 0.22+/-0.07. A total of 30 patients had documented ventricular arrhythmias, including ventricular tachycardia and sudden cardiac death. A regional increase in sympathetic nerves was observed around the diseased myocardium and blood vessels in all 30 hearts. The density of nerve fibers as determined morphometrically was significantly higher in group 1A patients (total nerve number 19.6+/-11.2/mm(2), total nerve length 3.3+/-3.0 mm/mm(2)) than in group 1B patients (total nerve number 13.5+/-6.1/mm(2), total nerve length 2.0+/-1.1 mm/mm(2), P<0. 05 and P<0.01, respectively). CONCLUSIONS: There is an association between a history of spontaneous ventricular arrhythmia and an increased density of sympathetic nerves in patients with severe heart failure. These findings suggest that abnormally increased postinjury sympathetic nerve density may be in part responsible for the occurrence of ventricular arrhythmia and sudden cardiac death in these patients.

Early expression of angiogenesis factors in acute myocardial ischemia and infarction.

BACKGROUND: When the myocardium is deprived of blood, a process of ischemia, infarction, and myocardial remodeling is initiated. Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator of vascular endothelial growth factor (VEGF) and is critical for initiating early cellular responses to hypoxia. We investigated the temporal and spatial patterns of expression of the alpha subunit of HIF-1 (HIF-1alpha) and VEGF in specimens of human heart tissue to elucidate the early molecular responses to myocardial hypoxia. METHODS: Ventricular-biopsy specimens from 37 patients undergoing coronary bypass surgery were collected. The specimens were examined by microscopy for evidence of ischemia, evolving infarction, or a normal histologic appearance. The specimens were also analyzed with the reverse-transcriptase polymerase chain reaction for HIF-1alpha and VEGF messenger RNA (mRNA) expression and by immunohistochemical analysis for the location of the HIF-1alpha and VEGF proteins. RESULTS: HIF-1alpha mRNA was detected in myocardial specimens with pathological evidence of acute ischemia (onset, <48 hours before surgery) or early infarction (onset, <24 hours before surgery). In contrast, VEGF transcripts were seen in specimens with evidence of acute ischemia or evolving infarction (onset, 24 to 120 hours before surgery). Patients with normal ventricles or evidence of infarction in the distant past had no detectable levels of either VEGF mRNA or HIF-1alpha mRNA. HIF-1alpha immunoreactivity was detected in the nuclei of myocytes and endothelial cells, whereas VEGF immunoreactivity was found in the cytoplasm of endothelial cells lining capillaries and arterioles. CONCLUSIONS: An increase in the level of HIF-1alpha is an early response to myocardial ischemia or infarction. This response defines, at a molecular level, one of the first adaptations of human myocardium to a deprivation of blood. HIF-1alpha is a useful temporal marker of acutely jeopardized myocardium.

Ischemia-reperfusion injury at the microvascular level: treatment by endothelin A-selective antagonist and evaluation by myocardial contrast echocardiography.

BACKGROUND: The purpose of this study was to verify whether endothelin A-antagonist administration at the time of coronary reperfusion preserves postischemic microvasculature and whether myocardial contrast echo (MCE) is able to detect pharmacologically induced changes in microvascular reflow. METHODS AND RESULTS: Twenty dogs underwent 90 minutes of LAD occlusion (OCC) followed by 180 minutes of reperfusion (RP). Five minutes before LAD reopening, an intravenous bolus (5 mg/kg) of LU 135252 was given in 10 dogs and vehicle in the remaining 10. At baseline (BSL), OCC, and 90 and 180 minutes of RP, microvascular flow (BF) was assessed by microspheres, and MCE was performed with intravenous echo contrast. MCE videointensity and BF were expressed as risk area/control ratio. Myocardial thickness of the risk area was calculated by 2D echo. No differences in BF between the 2 groups were observed at BSL, OCC, and 90 minutes of RP. At 180 minutes of RP, BF was decreased in controls (70+/-7.4% of BSL; P:<0.005 versus BSL) and preserved in LU 135252-treated animals (89+/-4% of BSL; P=NS versus BSL; P<0.05 versus controls). Videointensity at MCE closely followed the changes in BF observed in both groups throughout the protocol. Myocardial thickness at 180 minutes of RP increased to 138.6+/-9.9% of BSL in controls and remained at 108.9+/-7.4% of BSL in treated dogs (P<0.05). CONCLUSIONS: Endothelin A-antagonist treatment at the time of reperfusion significantly limited the progressive decrease in postischemic microvascular reflow and the increase in myocardial thickness. MCE allowed a reliable evaluation of pharmacologically induced changes in microvascular flow.

Biochemical diagnosis of liver disease.

It is important that clinicians and laboratorians, including clinical chemists and pathologists, recognize and understand the clinical significance of abnormal liver function tests. The liver regulates many important metabolic functions. Hepatic injury is associated with distortion of these metabolic functions. Hepatic disease can be evaluated and diagnosed by determining serum concentrations of a number of serum analytes. Many serum analytes exist to assist in the biochemical diagnosis of liver disease. The focus of this paper is on the analytes which are associated with hepatic necrosis, cholestasis, defects in excretion and end stage hepatic disease which results in decreased synthetic function. The abnormalities of these serum analytes will be correlated with the important types of liver disease.

Tropical sprue and subclinical enteropathy: a vision for the nineties.

Aside from infectious intestinal diseases with known etiology, there is a group of gastrointestinal disorders mainly affecting the small intestine of individuals predominantly living in and less often visiting or returning from the Third World, usually the tropics, and ranging from asymptomatic structural and/or functional abnormalities of the gastrointestinal mucosa (subclinical enteropathy, SE) to a fully symptomatic condition highlighted by malabsorption of nutrients with associated nutritional deficiencies responsive to folate and broad spectrum antibiotic treatment (tropical sprue, TS). Mounting evidence supports an infectious cause in many instances. The exact nature of the infection, whether initiated and/or perpetuated by enterotoxigenic coliform bacteria, virus(es) or a combination of these, is not clear. Further studies, including those using molecular techniques, are needed in order to clarify various aspects of these widely prevalent disorders.

Effects of chemical subendocardial ablation on activation rate gradient during ventricular fibrillation.

The mechanism by which an endocardial-epicardial activation rate gradient develops after 1 or 2 min of sustained ventricular fibrillation is unknown. We recorded from electrodes on the epicardium and from hook electrodes in the endocardium in three open-chest control dogs during prolonged ventricular fibrillation. The same recordings were also made in seven dogs after right ventricular subendocardial ablation with Lugol solution and in three dogs after substitution of air for the cavitary blood. The effects of these interventions, i.e., Lugol ablation (n = 2) and the exposure to air (n = 2), on the subendocardial Purkinje fiber transmembrane action potential properties were also evaluated in vitro using microelectrode recording techniques. The in vivo studies showed a significant endocardial-epicardial rate gradient in the control dogs and in dogs that had air substituted for the cavitary blood. In comparison, in dogs that underwent chemical subendocardial ablation, the activation cycle lengths for the endocardium and epicardium were not significantly different. The in vitro studies showed that subendocardial Purkinje fiber action potentials could still be recorded for up to 10 min of exposure to air. In comparison, in the tissues subjected to chemical ablation, no transmembrane action potentials could be recorded from either the Purkinje fibers or superficial ventricular muscle cells. We conclude that the development of an endocardial-epicardial activation rate gradient during prolonged ventricular fibrillation depends on the presence of intact subendocardial Purkinje fibers and ventricular myocytes. The retained cavitary blood is not responsible for the development of the rate gradient.

The mechanism of termination of reentrant activity in ventricular fibrillation.

The reentrant wave fronts in ventricular fibrillation (VF) have only a limited life span. The mechanisms by which these reentrant wave fronts terminate are unknown. We performed computerized mapping studies in six open-chest dogs before and after right ventricular subendocardial ablation with Lugol's solution. Recordings were made with 56 bipolar electrodes separated by 3 mm. Baseline pacing was performed on the right side of the tissue to create parallel activation wave fronts. A premature 50-V shock of either anodal or cathodal polarity was given to a bar electrode on the upper edge of the tissue. Counterclockwise reentrant wave fronts and VF were induced both before (60 episodes) and after (57 episodes) subendocardial ablation with either anodal or cathodal shocks. Among these reentrant wave fronts, 8 episodes before and 10 episodes after ablation had over 10 rotations (P = NS). The reentrant wave fronts in other episodes terminated with an average of 3.2 +/- 1.9 rotations before and 3.1 +/- 1.8 rotations after the ablation (P = NS). The reentrant wave-front cycle length was 118 +/- 19 milliseconds before and 124 +/- 20 milliseconds after ablation (P = .001). Conduction block occurred when the wave front was traveling across the myocardial fibers. When conduction was blocked in these episodes, the leading edge of the reentrant wave front encountered tissue that had been excited within the past 58 +/- 12 milliseconds (range, 28 to 77 milliseconds), which corresponded to 47 +/- 12% of the preceding VF cycle length. This period was significantly shorter than the recovery period in the same region that had allowed conduction (91 +/- 19 milliseconds; range, 48 to 137 milliseconds), which corresponded to 72 +/- 18% of the preceding VF cycle length (P < .001). In nine episodes, reentrant wave-front activity terminated when wave fronts that had originated from outside the mapped tissue interfered with the reentrant pathways. Conclusions are as follows: (1) The refractory period of fibrillating ventricular muscle ranges from 48 to 77 milliseconds. Because the refractory period is much shorter than the VF cycle length, a large excitable gap is present in the reentrant circuit. The presence of a large excitable gap contributes to reentrant wave-front termination. (2) Myocardial fiber orientation is an important determinant of the site of conduction block. (3) Although subendocardial ablation slowed the wave-front propagation, it did not prevent the generation and the maintenance of reentry and VF.

Clinical significance of serum high-molecular-mass alkaline phosphatase, alkaline phosphatase-lipoprotein-X complex, and intestinal variant alkaline phosphatase.

This paper is a study to identify the clinical significance of high-molecular-mass alkaline phosphatase (ALP:E:C..3.1.3.1.), ALP-lipoprotein-X complex (LP-X) and intestinal variant ALP. We used cellulose acetate and agarose gels and techniques including wheat germ lectin, cetavlon-diethyl ether, thermostatability, neuraminidase and L-phenylalanine to improve the electrophoretic separation of the alkaline phosphatase isoenzymes. Patients' serum samples were electrophoresed from a diverse group of individuals ill with cholestasis, neoplastic disease metastatic to the liver, hepatocellular carcinoma, cirrhosis, diabetes mellitus, and chronic renal disease. Agarose gels provided better separation of ALP isoenzymes than cellulose acetate gels. The results also indicated that high-molecular mass ALP is present in patient's serum in conditions associated with cholestasis especially caused by hepatic malignancy. High-molecular mass ALP was frequently found to co-exist with the liver isoenzyme and LP-XALP complex. The intestinal variant was identified in patients with malignancy, cirrhosis, chronic renal disease and diabetes mellitus. Intestinal ALP coexisted concomitantly with a variant intestinal ALP. Intestinal variant ALP is most likely composed of intestinal ALP attached to a cellular membrane-binding domain, or may be an artifact produced by neuraminidase incubation.

The epidemiology of traumatic death. A population-based analysis.

Despite the proliferation of trauma systems, there are no population-based data describing the epidemiology of traumatic death. To provide these data, we reviewed all trauma deaths occurring in San Diego (California) County during 1 year. There were 625 traumatic deaths during the study (27.3 deaths per 100,000 population per year). Motor vehicle trauma was the most common cause of injury leading to death (N = 344 [55.2%]; 15.0 annual deaths per 100,000 population). Central nervous system injuries were the most common cause of death (48.5%, or 13.2 deaths per 100,000 population per year). Sepsis was responsible for only 2.5% of the overall mortality. Based on life-table data, traumatic death resulted in an annual loss of 1091 years of life per 100,000 and an annual loss of 492 years of productivity per 100,000. Injury continues to account for an enormous loss of life despite improvements in survival wrought by trauma systems.

AIDS and malignant mesothelioma--is there a connection?

A 35-year-old male homosexual, a former intravenous drug abuser, was found to be human immunodeficiency virus (HIV) positive in 1984. He developed AIDS in 1987 and began treatment with zidovudine in 1989. One year later he developed left apical pleural blebs, a pneumothorax and an exudative pleural effusion. A malignant mesothelioma developed at the pleural blebs in the left apex. He was treated with adriamycin but rapid progression of the malignancy occurred and he died three months later. At autopsy, a malignant mesothelioma, causing respiratory failure and death, was found. The patient had no exposure to asbestos and asbestosis was not present at autopsy. We postulate that the development of malignant mesothelioma was probably related to HIV immune suppression or HIV and/or cytomegalovirus or zidovudine and is a complication of AIDS similar to the development of other malignant neoplasms in patients with AIDS.

Effects of subendocardial ablation on anodal supernormal excitation and ventricular vulnerability in open-chest dogs.

BACKGROUND: In Langendorff-perfused hearts and in hearts on cardiopulmonary bypass, chemical ablation of the subendocardium of both ventricles decreases ventricular vulnerability to fibrillation. It was hypothesized that the effects of ablation are a result of the elimination of the subendocardial Purkinje fiber network. This hypothesis has been supported by recent observations that the supernormal excitability that is demonstrable in the Purkinje fibers is associated with arrhythmogenesis. METHODS AND RESULTS: We tested this hypothesis on 10 open-chest dogs by evaluating the strength-interval curves of anodal and cathodal stimulation with the assistance of computerized mapping techniques. The ventricular fibrillation threshold was also determined. The same test was then performed after chemical ablation of the subendocardium of either the right ventricle (six dogs) or both ventricles (four dogs). Anodal supernormality was consistently demonstrated in all the dogs studied both before and after subendocardial ablation. The ventricular fibrillation thresholds were 23 +/- 5 mA both before and after right ventricular subendocardial ablation (p = NS). The ventricular fibrillation thresholds before and after biventricular subendocardial ablation were 25 +/- 3 and 22 +/- 10 mA, respectively (p = NS). CONCLUSIONS: We conclude that 1) subendocardial ablation does not decrease ventricular vulnerability when the heart is in situ and is not on cardiopulmonary bypass and 2) anodal supernormal excitability can be demonstrated in ventricles without a subendocardial Purkinje fiber network.