Microvascular injury in reperfused infarcted myocardium: noninvasive assessment with contrast-enhanced echoplanar magnetic resonance imaging

OBJECTIVES: The purpose of this study was to measure the accumulation of labeled albumin and to visualize its distribution pattern in reperfused infarcted myocardium as a function of time between onset of reperfusion and administration of the tracer. BACKGROUND: Myocardial microvascular injury leads to leakage of albumin from the intravascular space. Quantitative measurements of GdDTPA-albumin with inversion recovery echoplanar imaging (IR-EPI) may allow noninvasive monitoring of microvascular injury. METHODS: After 1 h of coronary artery occlusion, 56 rats were injected with GdDTPA-albumin or 123I-GdDTPA-albumin either immediately before reperfusion or 1/2, 1 or 24 h after reperfusion. GdDTPA-albumin in blood, normal myocardium and reperfused infarction was dynamically measured with IR-EPI during 1 h postinjection (PI). Autoradiograms were obtained at 15 min PI. Accumulation of labeled albumin in myocardium was expressed as the ratio of myocardial to blood content. RESULTS: In normal myocardium, the ratio of changes of relaxation rate-ratio (deltaR1-ratio) was 0.12+/-0.01 and did not change over 1 h. In reperfused infarction, however, the deltaR1-ratio increased after administration. Animals given GdDTPA-albumin before reperfusion exhibited fastest accumulation (deltaR1-ratio 15 min PI: 0.56+/-0.03) and essentially homogeneous distribution. The accumulation was slower when administered at 1/2, 1 and 24 h after reperfusion (deltaR1-ratios 15 min PI: 0.39+/-0.03; 0.31+/-0.04; 0.16+/-0.01; p < 0.001 compared to administration before reperfusion). Moreover, the tracer accumulated predominantly in the periphery of the injury zone. CONCLUSIONS: Amount and distribution pattern of labeled albumin in reperfused infarction are modulated by duration of reperfusion. The accumulation of GdDTPA-albumin can be quantified by IR-EPI. Thus, IR-EPI may be useful to noninvasively monitor myocardial microvascular injury in reperfused infarction.     

Non-invasive detection of ongoing neuronal population activity in normal human hippocampus

In a prospective series of symptomatic adult hydrocephalus characterized by gait disturbance, cognitive impairment, and/or urinary incontinence, 88 of 118 patients (75%) had additional akinetic, tremulous, hypertonic, or hyperkinetic movement disorders. Their prevalence was highest in patients with idiopathic normal pressure hydrocephalus (NPH) of the elderly (56/65 patients, 86%), and they were less frequent in patients with secondary NPH (10/15, 66%), with nonhydrodynamic atrophic/other hydrocephalus (20/33, 61%), and with obstructive hydrocephalus/aqueductal stenosis (2/5, 40%). Akinetic symptoms were found in 73 of 118 patients (62%), and the most frequent movement disorder was upper extremity bradykinesia (55%). Akinetic, tremulous, hypertonic, and hyperkinetic movement disorders were exclusively secondary to causes not related to hydrocephalus in 24 of 118 patients (20%). The proportion of patients with movement disorders not attributable to only such causes was highest in the idiopathic NPH group (44/65, 68%). Thirteen of 118 patients (11%) presented with a parkinsonian syndrome. There was evidence for coexistent Parkinson's disease in four of these patients. Parkinsonism was found to be secondary to NPH in five patients and was found improved after shunting. Akinetic symptoms in patients with NPH generally responded favorably to CSF diversion, which was evident in 80% of a subset of this group. Various other movement disorders did not show definite improvement. The high prevalence of bradykinesia and other akinetic symptoms in NPH and the beneficial effect of shunting on such symptoms suggest that NPH may cause a more generalized disorder of motor function.     

The role of leukocyte depletion in reducing injury to myocardium and lung during cardiopulmonary bypass

Activated leukocytes and oxygen free radicals have been implicated in the pathogenesis of heart and lung injury after reperfusion and during cardiopulmonary bypass. This study was designed to determine whether leukocyte depletion prevents injury to the heart and lung during cardiopulmonary bypass. Twenty-eight open heart surgeries were performed in this study. In Group F, leukocyte depletion was performed with an LG-6 arterial line filter after aortic declamp (n = 14). Leukocyte depletion was not performed during cardiopulmonary bypass in Group C (n = 14). Thereafter, cardiac and lung function were assessed in the 24 hr after reperfusion. The total catecholamine dose used for 24 hr after reperfusion (r) was 61.9 +/- 13.4 in Group C and 43.9 +/- 19.2 in Group F (p < 0.05). CK-MB at 3 and 6 hr after reperfusion was 65.9 +/- 13.5 and 64.8 +/- 15.8 in Group C and 45 +/- 11.8 and 38 +/- 10.8 in Group F, respectively (p < 0.05). The pulmonary index after reperfusion at 3 and 6 hr was 1.7 +/- 0.5 and 1.3 +/- 0.4 in Group C and 0.7 +/- 0.3 and 0.6 +/- 0.4 in Group F, respectively (p < 0.05). There was significantly better preserved lung function in Group F. In conclusion, leukocyte depletion was significantly effective in preserving heart and lung function during cardiopulmonary bypass.     

Serial prognostic capabilities of electrocardiographic indices of infarcted and hibernating myocardium in predicting short- and long-term outcome following coronary artery bypass surgery

Concentrations and ex vivo production of interleukin 1 beta (IL-1), tumour necrosis alpha (TNF), interleukin 6 (IL-6), interleukin-1 receptor antagonist (IL-1RA) and TNF soluble receptors (sTNF-receptors, P55 and P75) were measured in bronchoalveolar lavage (BAL) fluid and blood in 23 HIV-seropositive (HIV+) patients with Pneumocystis carinii pneumonia (PCP) and compared with values found in healthy HIV-seronegative (HIV-) controls and asymptomatic HIV+ subjects. Concentrations of the proinflammatory cytokine IL-1 beta were increased in BAL fluid of HIV+ patients with PCP (184 +/- 47 pg mL-1) compared with undetectable levels in healthy control subjects (P = 0.0001). In plasma of these patients higher concentrations of the anti-inflammatory cytokine IL-1RA were found during acute PCP than after recovery (2.1 +/- 0.7 vs. 0.5 +/- 0.2 ng mL-1, P = 0.01). No correlations could be found between cytokine concentrations and clinical severity of the infection. Corticosteroid treatment did not influence cytokine concentrations in BAL or blood, nor did it suppress the production in alveolar cells. In whole-blood cultures, however, lipopolysaccharide (LPS)-stimulated production was significantly suppressed for IL-1 (1.3 vs. 5.5 ng mL-1, P = 0.009) and for IL-6 (0.6 vs. 2.5 ng mL-1, P = 0.01). The overall data show that in HIV+ patients with PCP (similar to what we had found previously in HIV-patients with PCP) proinflammatory cytokines are more prominently present in BAL, whereas anti-inflammatory reaction is predominant in the circulation.     

The effect of uric acid, creatine phosphate and carnitine on lipid peroxidation in cerebral cortex and myocardium homogenates

BACKGROUND: Uric acid as the product of purine nucleotide degradation is an integrate component of blood plasma. This metabolite is considered to be one of the important naturally occurring antioxidants building up the antioxidation system of the organism. Creatine phosphate and carnitine are important substances participating in energy metabolism of the cells. Energy production is closely related to the level of reduction systems and thus also to the antiradical ability of the cell. By this mechanism could creatine phosphate and carnitine improve the antioxidative capacity of the cell. METHODS: In homogenates of rat brain cortex and myocardium was the production of oxygen radicals stimulated by mixture of Fe2+ ions and ascorbate. Oxygen radicals may induce lipid peroxidation by the means of the reaction with lipid structures. We tried to inhibit the process of lipid peroxidation by addition of uric acid, creatine phosphate and carnitine into the incubation medium. Intensity of lipoperoxidation was measured by detection of substances giving positive reaction with thiobarbituric acid (TBA) in homogenates of brain cortex and myocardium. RESULTS: Uric acid in concentrations of 1 and 0.5 mmol.l-1 markedly inhibits the production of compounds reacting with TBA. This effect was not found in 0.05 mmol.l-1 concentration. Creatine phosphate and carnitine in 1 mmol.l-1 concentrations also decreased the value of lipid peroxides in homogenates of brain cortex, but their effect was lower than the effect of uric acid. This effect was not seen in myocardium homogenates.     

Skeletal muscle lactate accumulation and creatine phosphate depletion during heavy exercise in congestive heart failure. Cause of limited exercise capacity?

OBJECTIVE: To study the mechanisms of limited exercise capacity and skeletal muscle energy production in male patients with congestive heart failure. DESIGN: Muscle biopsy study. PATIENTS: Skeletal muscle metabolic response to maximal bicycle exercise was studied in 10 patients with chronic congestive heart failure (ejection fraction 0.22 +/- 0.05; peak oxygen consumption, VO2 15.1 +/- 4.9 ml.min-1.kg-1) and in nine healthy subjects (peak VO2 33.5 +/- 6.7 ml.min-1.kg-1). Activities of skeletal muscle enzymes were measured from the vastus lateralis muscle of 48 patients (ejection fraction 0.24 +/- 0.06, peak VO2 17.4 +/- 5.4 ml.min-1.kg-1) and 36 healthy subjects (peak VO2 38.3 +/- 8.4 ml.min-1.kg-1). RESULTS: Although blood lactate levels were lower in patients than in healthy subjects (2.2 +/- 0.3 vs 5.2 +/- 0.6 mmol.l-1; P < 0.001) at peak exercise (96 +/- 11 W for patients and 273 +/- 14 W for controls), skeletal muscle lactate was similarly elevated (25.6 +/- 3.2 vs 22.7 +/- 2.7 mmol.kg-1) and creatine phosphate was equally depressed (P < 0.02) to low levels (7.0 +/- 1.9 vs 6.7 +/- 0.9 mmol.kg-1). The muscle ATP decreased by 21% (P < 0.05) and 8% (P < 0.01) in the patients and controls, respectively. Activities of rate limiting enzymes of the citric acid cycle (alpha-ketoglutarate dehydrogenase) and oxidation of free fatty acids (carnitine palmitoyltransferase II) were 48% and 21% lower than in controls, but the mean phosphofructokinase activity was unchanged in congestive heart failure. CONCLUSIONS: It seems that the main limiting factor of exercise performance during heavy exercise is the same in congestive heart failure and healthy subjects, a high rate of skeletal muscle lactate accumulation and high-energy phosphate depletion. In congestive heart failure, the low activity of aerobic enzymes is likely to impair energy production and lead to lactate acidosis at low workloads.     

Occurrence of free creatine, phosphocreatine and creatine phosphokinase in adipose tissue

We evaluated brown and white adipose tissues for the presence of creatine, phosphocreatine and creatine phosphokinase activity. In rats 3.6 and 0.4 mumol of total creatine were found per g wet weight of brown and white adipose tissues, respectively. We were able to identify creatine by thin-layer chromatography after a pulse label of [14C]creatine had been given in vivo. Free creatine and phosphocreatine were shown to occur by column chromatography. Of the total creatine of brown adipose tissue, approximately one third to one half were attributable to phosphocreatine. The activity of creatine phosphokinase was demonstrated in both white and brown adipose tissue, the values of the latter prevailing over those of the former by a factor of 200, if based on wet weight, or 50, if expressed as specific enzyme activity. The labeling of total creatine in vivo proceeded much faster in adipose tissue than in skeletal muscle. The results strongly suggest that the energy metabolism of adipose tissue is closely dependent on the presence of creatine. The specific activities of free creatine and phosphocreatine of brown adipose tissue differed strikingly as long as 24 h after radioactive creatine was injected; this difference points to a metabolic or structural compartmentation of creatine.     

Mitochondrial intermembrane inclusion bodies: the common denominator between human mitochondrial myopathies and creatine depletion, due to impairment of cellular energetics

Mitochondrial inclusion bodies are often described in skeletal muscle of patients suffering diseases termed mitochondrial myopathies. A major component of these structures was discovered as being mitochondrial creatine kinase. Similar creatine kinase enriched inclusion bodies in the mitochondria of creatine depleted adult rat cardiomyocytes have been demonstrated. Structurally similar inclusion bodies are observed in mitochondria of ischemic and creatine depleted rat skeletal muscle. This paper describes the various methods for inducing mitochondrial inclusion bodies in rodent skeletal muscle, and compares their effects on muscle metabolism to the metabolic defects of mitochondrial myopathy muscle. We fed rats with a creatine analogue guanidino propionic acid and checked their solei for mitochondrial inclusion bodies, with the electron microscope. The activity of creatine kinase was analysed by measuring creatine stimulated oxidative phosphorylation in soleus skinned fibres using an oxygen electrode. The guanidino propionic acid-rat soleus mitochondria displayed no creatine stimulation, whereas control soleus did, even though the GPA solei had a five fold increase in creatine kinase protein per mitochondrial protein. The significance of these results in light of their relevance to human mitochondrial myopathies and the importance of altered cell energetics and metabolism in the formation of these crystalline structures are discussed.     

Non-invasive monitoring of bronchial inflammation in asthma

The present consensus on the diagnosis and treatment of asthma relies on symptoms and lung function measurements for the monitoring of disease severity. Even though this probably remains the cornerstone of asthma management, the rapidly increasing insight into the pathogenesis and pathophysiology of the disease is presently leading to the development of more direct measurements of airway inflammation, which may provide potentially relevant information on its clinical course and prognosis. However, at present none of these has sufficiently been validated for current use in monitoring patients with asthma. First, there are new ways of looking at symptoms and lung function. Careful measurements of symptoms by visual analogue scale (VAS) are suggesting that inflammatory activity within the airways can be subjectively perceived, a sensitivity which may be blunted in patients with brittle asthma. In addition, modern physiological parameters, such as the degree of bronchodilatation following a deep breath (M/P-ratio), are strongly associated with airway inflammation. Second, there are multiple cellular and/or soluble markers of inflammation in peripheral blood (using PCR, in situ hybridization, flow cytometry, or circulating mediators and cytokines) and in urine (LTE4, EPX). Recently this has been extended by similar measurements in hypertonic saline-induced sputum (cell differentials and specific stainings on cytospins, flow cytometry, and levels of e.g. ECP, IL-5, IL-8). Finally, mediators and cytokines in the condensate of exhaled air (H2O2, leukotrienes, IL-5?) as well as exhaled NO are currently under evaluation. Adding such markers of airway inflammation as guides in asthma therapy is potentially useful. As a first step towards such a new approach we have recently shown that adding the reduction of airway hyperresponsiveness to the aims of asthma therapy leads to a better clinical as well as histological outcome after two years of treatment. In conclusion, there are new and exciting perspectives in the monitoring of disease severity in asthma in the future. Longitudinal studies presently ongoing will elucidate which parameter is potentially most useful in guiding asthma management.     

Maintained coupling of oxidative phosphorylation to creatine kinase activity in sarcomeric mitochondrial creatine kinase-deficient mice

The importance of mitochondrial creatine kinase (mi-CK) in oxidative muscle was tested by studying the functional properties of in situ mitochondria in saponin-skinned muscle fibres from sarcomeric mi-CK-deficient (mutant) mice. Biochemical analyses showed that the lack of mi-CK in mutant muscle was associated with a decrease in specific activity of MM-CK in mutant ventricle, and increase in mutant soleus (oxidative) muscle. Lactate dehydrogenase activity and isoenzyme analysis showed an increased glycolytic metabolism in mutant soleus. No change was observed in ventricular muscle. In control animals, the apparent K(m) of mitochondrial respiration for ADP in ventricle and soleus (232 +/- 36 and 381 +/- 63 microM, respectively) was significantly reduced in the presence of creatine (52 +/- 8 and 45 +/- 12 microM, respectively). There was no change in the K(m) in oxidative fibres from mutant mice (258 +/- 27 and 399 +/- 66 microM, respectively) compared with control, though surprisingly, it was also significantly decreased in the presence of creatine (144 +/- 8 and 150 +/- 27 microM, respectively) despite the absence of mi-CK. It is proposed that in mutant (and perhaps normal) oxidative tissue, cytosolic MM-CK can relocate to the outer mitochondrial membrane, where it is coupled to oxidative phosphorylation by close proximity to porin, and the adenine nucleotide translocase. Such an effect can preserve the functioning of the CK shuttle and the energetic properties of mi-CK deficient tissue.     

Non-invasive diagnosis of venous thromboembolism in outpatients

BACKGROUND: We designed a simple and integrated diagnostic algorithm for acute venous thromboembolism based on clinical probability assessment of deep-vein thrombosis (DVT) or pulmonary embolism (PE), plasma D-dimer measurement, lower-limb venous compression ultrasonography, and lung scan to reduce the need for phlebography and pulmonary angiography. METHODS: 918 consecutive patients presenting at the emergency ward of the Geneva University Hospital, Geneva, Switzerland, and H?pital Saint-Luc, Montreal, Canada, with clinically suspected venous thromboembolism were entered into a sequential diagnostic protocol. Patients in whom venous thromboembolism was deemed absent were not given anticoagulants and were followed up for 3 months. FINDINGS: A normal D-dimer concentration (<500 microg/L by a rapid ELISA) ruled out venous thromboembolism in 286 (31%) members of the study cohort, whereas DVT by ultrasonography established the diagnosis in 157 (17%). Lung scan was diagnostic in 80 (9%) of the remaining patients. Venous thromboembolism was also deemed absent in patients with low to intermediate clinical probability of DVT and a normal venous ultrasonography (236 [26%] patients), and in patients with a low clinical probability of PE and a non-diagnostic result on lung scan (107 [12%] patients). Pulmonary angiography and phlebography were done in only 50 (5%) and 2 (<1%) of the patients, respectively. Hence, a non-invasive diagnosis was possible in 866 (94%) members of the entire cohort. The 3-month thromboembolic risk in patients not given anticoagulants, based on the results of the diagnostic protocol, was 1.8% (95% CI 0.9-3.1). INTERPRETATION: A diagnostic strategy combining clinical assessment, D-dimer, ultrasonography, and lung scan gave a non-invasive diagnosis in the vast majority of outpatients with suspected venous thromboembolism, and appeared to be safe.     

The contribution of assays for lymphocyte capping and creatine kinase to detection of the Becker-type dystrophy trait

Members of three unrelated families with the mild Becker type of muscular dystrophy were subjected to lymphocyte capping tests and measurements of serum creatine kinase activity. Both tests correctly identified all nine affected males, but only the capping test was abnormal in seven of eight obligate carriers. The number of capped cells in carriers and affected persons with the Becker-type dystrophy was generally intermediate between those observed for individuals with the Duchenne trait and normal controls, thus potentially aiding in the differential diagnosis between the two myopathies. The lack of sensitivity of measurements of serum creatine kinase activity in identifying carriers is further complicated by the difficulty of establishing reliable reference intervals for this enzyme in 204 healthy controls. Detailed directions for the performance of the capping test are presented.     

99mTc-HL91: "hot spot" detection of ischemic myocardium in vivo by gamma camera imaging

BACKGROUND: 99mTc-HL91 is a new hypoxia imaging agent that demonstrates increased uptake and retention in globally hypoxic myocardium in vitro. The purpose of this study was to determine whether 99mTc-HL91 could detect regional ischemia in vivo by gamma camera imaging. METHODS AND RESULTS: Eight open-chest dogs with left circumflex (LCx) stenoses were studied. Injection of 5 mCi of 99mTc-HL91 and microspheres was followed by imaging over 4 hours. Heart slices were imaged, then stained with triphenyltetrazolium chloride (TTC), and tissues were well-counted. TTC staining demonstrated no injury. Mean LCx blood flow was 0.32+/-0.04 mL x min(-1) x g(-1), and mean left anterior descending coronary artery (LAD) flow was 0.96+/-0.02 mL x min(-1) x g(-1) (ratio, 0.33). "Hot spots" were detected in 8 of 8 experiments in vivo within 60 minutes and improved over 4 hours. Region of interest analysis of LCx/LAD activity ratios demonstrated significant increases within 30 minutes (final ratio, 3.0; P<0.05). LCx and LAD washout curves demonstrated significant differences within 15 minutes. Washout curves were biexponential over 1 hour, followed by linear retention from 1 to 4 hours. Four-hour fractional retention was 0.12 for LAD and 0.44 for LCx (P<0.01). Myocardial flow versus tracer uptake demonstrated 2 phases: phase 1 (flow, 0.05 to 0.7 mL x min(-1) x g(-1)) had an inverse linear correlation (r= -0.80); phase 2, (flow, >0.7 mL x min(-1) x g(-1)) had no correlation. Ischemic heart/liver ratios remained near 1.0 for 4 hours. CONCLUSIONS: 99mTc-HL91 positively identifies regional myocardial ischemia in a canine model using 99mTc imaging. Quantitative techniques allowed identification of ischemic myocardium within 15 minutes of tracer administration.     

Effect of acetylsalicylic acid on nitric oxide production in infarcted heart in situ

The effect of Acetylsalicylic Acid (ASA, Aspirin) on the myocardial production of the inducible form of nitric oxide synthase (iNOS) and the oxidation products of nitric oxide (nitrite, NO-2 and nitrate, NO-3: NOx) were studied in the rabbit heart two days after ligation of a branch of the left circumflex coronary artery. ASA was administered intravenously as AspisolR, DL-Lysinmono(acetylsalicylate) which is soluble in water. Animals received a total dose of 250, 375, or 500 mg/kg of ASA in five divided doses intravenously. Significant inhibition of iNOS was noted in the infarcted portion of the myocardium at 375 and 500 mg/kg of ASA. The reduction in myocardial nitric oxide (NO) production was paralleled by a diminution in coronary arterial-venous difference of NOx, demonstrating that ASA inhibition extended also to the oxidation products of NO. ASA is an inhibitor of cyclooxygenase (COX). The inhibition of iNOS by ASA demonstrates the close relationship between COX and iNOS activity in the heart in situ. Whether activity of the infarcted heart is influenced by the diminution in the production of NO by ASA is not known.