Effect of losartan in aging-related endothelial impairment

Aging is associated with progressive deterioration in endothelial function. We hypothesized that losartan may represent a useful therapeutic strategy to ameliorate endothelial function in aged subjects. Eighteen healthy older subjects (mean age 75 +/- 3 years) were prospectively randomized in a double-blind, crossover fashion to receive either losartan 50 mg/day or placebo for 6 weeks. Subjects were switched to the opposite arm after a 2- week washout period. Flow-mediated dilation (FMD) in the brachial artery and plasma levels of vascular cell adhesion molecule-1, intercellular adhesion molecule (ICAM), moncocyte chemoattractant 1 protein, and E-selectin were measured in both arms at the beginning and end of the 6-week period. Losartan resulted in a 6-mm Hg decrease in systolic blood pressure (from 130 +/- 12 to 124 +/- 13 mm Hg), which was no different from placebo (132 +/- 12 to 127 +/- 13 mm Hg). FMD increased from 3.1 +/- 0.6% to 3.9 +/- 0.6% after losartan, and decreased from 3.3 +/- 0.3% to 2.4 +/- 0.6% after placebo (p = NS for both). In contrast, losartan reduced circulating concentrations of vascular cell adhesion molecule 1 (750 +/- 73 to 572 +/- 39), ICAM (405 +/- 26 to 196 +/- 10), and moncocyte chemoattractant 1 protein (560 +/- 56 to 423 +/- 35) (p <0.01 for all by analysis of variance), but not E-selectin. On univariate analyses, the strongest predictor of baseline endothelial function and change in FMD with losartan was low-density lipoprotein. There was a negative correlation between baseline endothelial function and change in FMD in response to losartan (r(2) = -0.75, p = 0.0003). Baseline ICAM levels alone significantly correlated with low-density lipoprotein cholesterol (r(2) = 0.54, p = 0.02) and weakly correlated with total cholesterol (r(2) = 0.47, p = 0.05). Thus, administration of losartan for a duration of 6 weeks has favorable effects on inflammatory markers in healthy older subjects, but does not alter peripheral conduit endothelial function.     

Abnormal function of the bone marrow microenvironment in chronic myelogenous leukemia: role of malignant stromal macrophages

The bone marrow microenvironment supports and regulates the proliferation and differentiation of hematopoietic cells. Dysregulated hematopoiesis in chronic myelogenous leukemia (CML) is caused, at least in part, by abnormalities in CML hematopoietic progenitors leading to altered interactions with the marrow microenvironment. The role of the microenvironment itself in CML has not been well characterized. We examined the capacity of CML stroma to support the growth of long-term culture-initiating cells (LTC-IC) obtained from normal and CML marrow. The growth of normal LTC-IC on CML stroma was significantly reduced compared with normal stroma. This did not appear to be related to abnormal production of soluble factors by CML stroma because normal LTC- IC grew equally well in Transwells above CML stroma as in Transwells above normal stroma. In addition, CML and normal stromal supernatants contained similar quantities of both growth-stimulatory (granulocyte colony-stimulating factor (CSF), interleukin-6, stem cell factor, granulocyte-macrophage CSF, and interleukin-1 beta) and growth- inhibitory cytokines (transforming growth factor-beta, macrophage inflammatory protein-1 alpha, and tumor necrosis factor-alpha). The relative proportion of different cell types in CML and normal stroma was similar. However, polymerase chain reaction and fluorescence in situ hybridization studies showed the presence of bcr-abl-positivo cells in CML stroma, which were CD14+ stromal macrophages. To assess the effect of these malignant macrophages on stromal function, CML and normal stromal cells were separated by fluorescence-activated cell sorting into stromal mesenchymal cell (CD14-) and macrophage (CD14+) populations. CML and normal CD14- cells supported the growth of normal LTC-IC equally well. However, the addition of CML macrophages to normal or CML CD14- mesenchymal cells resulted in impaired progenitor support. This finding indicates that the abnormal function of CML bone marrow stroma is related to the presence of malignant macrophages. In contrast to normal LTC-IC, the growth of CML LTC-IC on allogeneic CML stromal layers was not impaired and was significantly better than that of normal LTC-IC cocultured with the same CML stromal layers. These studies demonstrate that, in addition to abnormalities in CML progenitors themselves, abnormalities in the CML marrow microenvironment related to the presence of malignant stromal macrophages may contribute to the selective expansion of leukemic progenitors and suppression of normal hematopoiesis in CML.     

Kinetic evaluation of the pool sizes and proliferative response of neutrophils in bacterially challenged aging mice

Clinical observations during infection suggest that in aged patients, the kinetic or proliferative responses of neutrophils to infection may be deranged. To test this hypothesis, the neutrophil responses of 6- month-old and 30-month-old mice were compared. After intrapulmonary injection of Escherichia coli, young mice exhibited neutrophilia and diminution of the neutrophil storage pool (NSP) by a mean of 6.4 x 10(6) neutrophils/two femurs. This was accompanied by an increase in the pool of CFU-GM from a control value of 1.1 x 10(5) cells/two femurs (range 0.7 to 1.4) to 1.5 x 10(5) (1.1 to 1.9) (P less than .05) and the thymidine suicide (relative proliferative rate) of CFU-GM rose from 27% (19 to 42) to 51% (31 to 61) (P less than .05). Furthermore, the CFU-GM of infected young mice displayed enhanced differentiation to the neutrophil series. In contrast, old mice exhibited a greater mean diminution of the NSP: 12.8 x 10(6) neutrophils. Also, old mice experienced a reduction in CFU-GM from 2.3 x 10(5) (1.0 to 3.9) (controls) to 1.3 x 10(5) (1.2 to 1.5)/two femurs (P less than .05), a reduction in the proliferation of CFU-GM and reduced differentiation of CFU-GM to neutrophils. These experiments establish that the neutrophil response of infected old mice is disordered, with exaggerated depletion of the NSP and lack of stimulus-driven granulocytopoiesis as reflected by a paradoxical reduction in the number and proliferative rate of precursors. This defect may be compounded by decreased differentiation of precursors to neutrophils.     

Changes in intramyocardial ST segment voltage and gas tensions with regional myocardial ischemia in the dog.

This study was designed to evaluate the sensitivity of changes in myocardial carbon dioxide and oxygen tensions as indicators of regional myocardial ischemia and also to determine to what extent these changes can be related to changes in intramyocardial ST segment voltage. Changes in ST segment voltage recorded in unipolar epicardial electrodes proved to be a less-sensitive indicator of underlying myocardial ischemia than were changes in ST segment voltage recorded in unipolar intramyocardial electrodes. In 9 dogs, regional ischemia was produced by placing a variable constrictor on the left circumflex coronary artery; circumflex flow was monitored. Myocardial carbon dioxide and oxygen tensions were measured using a mass spectrometer. Unipolar electrograms were recorded using a multicontact plunge electrode. With progressive degrees of proximal stenosis, ranging from a critical stenosis, which is associated with a decrease in mean flow of less than 15%, to a severe stenosis associated with and 80% decrease, ST voltage increased 21 mv and carbon dioxide tension increased 84 mm Hg, but oxygen tension decreased only 7 mm Hg. The study suggests that increases in intramyocardial ST segment voltage, an index of myocardial ischemia, are associated with parallel increases in myocardial carbon dioxide tension, each providing a more sensitive quantitative correlate of regional myocardial ischemia than do decreases in oxygen tension. The local accumulation of carbon dioxide may be an important pathophysiological mechanism in myocardial ischemia.     

A randomized placebo-controlled trial of combined early intravenous captopril and recombinant tissue-type plasminogen activator therapy in acute myocardial infarction.

The adjunctive use of intravenous captopril with tissue plasminogen activator early during acute myocardial infarction offers theoretic advantages of diminishing left ventricular volume, preventing ventricular dilation and improving patient survival. To test the safety and efficacy of combined early administration of intravenous captopril and recombinant tissue-type plasminogen activator (rt-PA), 38 patients treated with rt-PA 3 +/- 0.3 h (mean +/- SE) after the onset of myocardial infarction were randomized to intravenous followed by oral captopril or placebo therapy. They underwent cardiac catheterization with measurement of hemodynamic variables and left ventricular function and determination of serum renin, angiotensin and aldosterone levels on days 1 and 7. Oral administration of the selected agent was continued for 3 months along with other antianginal medications, including nonangiotensin-converting enzyme inhibitor vasodilators. Repeat measurements of left ventricular function were obtained before hospital discharge and at 3 months. There were no significant differences in baseline clinical characteristics between groups. One patient in the captopril-treated group became hypotensive during intravenous therapy, requiring discontinuation of treatment. Compared with the placebo-treated group, the captopril-treated group had significant reductions at day 7 in left ventricular end-diastolic pressure (22.5 +/- 1.5 versus 16.3 +/- 1.6 mm Hg, p less than 0.01) and mean systemic arterial pressure (93.6 +/- 3.3 versus 86.2 +/- 2.7 mm Hg, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial imaging with thallium-201: a multicenter study in patients with angina pectoris or acute myocardial infarction

A multicenter study of rest and exercise thallium-201 myocardial imaging in 190 patients from five centers was performed. Exercise images were obtained after graded treadmill or bicycle stress with use of five different gamma camera models and were interpreted by the originating investigator without knowledge of other clinical data. Of 42 patients with less than 50 percent coronary stenosis, 4 (10 percent) had a resting image defect, 1 (2 percent) a new exercise defect and 5 (12 percent) either a resting or an exercise image defect, or both. Of 148 patients with coronary stenosis of 50 percent or greater, 64, (45 percent) had an image defect in the study at rest, 90 (61 percent) had new or increased defects after exercise, and 115 (78 percent) had resting or exercise defects, or both. New exercise image defects were more common than exercise S-T depression (90 of 148 [61 percent] versus 62 of 148[42 percent]; P less than 0.01). In a second group of 111 patients with acute myocardial infarction studied at three centers, 90 patients (81 percent) had image defects compared with 71 (64 percent) two had new electrocardiographic Q waves (P less than 0.01). Smaller infractions, as assessed with serum enzyme values, and diaphragmatic infarctions were less commonly detected than larger or anterior infarctions. These findings suggest that myocardial imaging complements the electrocardiographic identification of acute myocardial infarction of exericse-induced myocardial ischemia.     

Wound protectors mitigate superficial surgical site infections after pancreatoduodenectomy

Background

Whether the choice of antibiotic prophylaxis, the type of incision, or the use of wound protectors decreases surgical site infections (SSIs) in patients undergoing pancreatoduodenectomy (PD) remains unknown.

ACE Inhibitors in Heart Failure: Prospects and Limitations

ACE inhibitors have been shown to be effective in reducing the morbidity and mortality of patients with left ventricular systolic dysfunction, but their application to clinical practice in this situation is still limited. In part, the failure to prescribe an ACE inhibitor to a patient with left ventricular systolic dysfunction is due to perceptions regarding their side effects, such as cough and renal dysfunction. Relatively few patients with left ventricular systolic dysfunction and a serum creatinine ≥2 mg/dl receive an ACE inhibitor in clinical practice. In this situation one should consider an agent such as fosinopril, which is metabolized by the liver as well as secreted by the kidney. In patients with moderate renal dysfunction, fosinopril has been well tolerated without an increase in serum creatinine. In patients who develope cough due to an ACE inhibitor, consideration should be given to an angiotensin II type 1 receptor blocking agent, such as losartan. The relative safety and efficacy of an ACE inhibitor compared with an angiotensin II type 1 receptor blocking agent is being explored in a prospective randomized trial (Evaluation of Losartan In The Elderly [ELITE]), as well as the safety and pharmacological effectiveness of adding an angiotensin II receptor antagonist to an ACE inhibitor (Randomized Angiotensin receptor antagonists–ACE-inhibitor Study [RAAS]). There may also be a role for the combination of an aldosterone receptor antagonists and an ACE inhibitor in patients with left ventricular systolic dysfunction. Once an ACE inhibitor is administered to a patient with left ventricular systolic dysfunction it should be continued indefinitely. ACE inhibitors may be of value not only in preventing the progression of heart failure but also in reversing endothelial dysfunction and preventing the development of atherosclerosis and its consequences, such as myocardial infarction.     

Comparison of supine and erect bicycle exercise electrocardiography in coronary heart disease: Accentuation of exercise-induced ischemic ST depression by supine posture

Exercise-induced electrocardiographic ST depression was compared during supine and erect graded bicycle exercise in 43 patients with chest pain but no prior myocardial infarct; all had ≥1 mm of ST depression during either erect or supine exercise; 16 had multivessel, 24 had 1-vessel and 3 had no coronary artery disease. Supine exercise used 4 minutes/stage and erect exercise used either 4 minutes or 3 minutes/stage with identical graded work loads for both postures. Chest pain occurred in 31 patients during erect and in 29 during supine exercise. ST depression was ≥1 mm in 28 patients during erect exercise and in all 43 during supine exercise (p <0.001); mean maximal ST depression was 1.3 ± 0.2 mm during erect and 2.6 ± 0.2 mm during supine exercise (p <0.001). Maximal work load was higher during erect than supine exercise (745 ± 32 versus 678 ± 32 kpm/min; p <0.001). The accentuation of ST depression by supine posture was not attributable to the changes in heart rate, rate-pressure product or mean blood pressure during supine versus erect exercise. In the 10 patients who had 2 erect bicycle tests using work load durations of 3 and 4 minutes, the maximal ST depression was not significantly different (erect 3 minutes 1.3 ± 0.5 mm and erect 4 minutes 1.4 ± 0.4 mm). In 7 patients who also had a maximal treadmill exercise test, the maximal ST depression was significantly greater during supine exercise (2.3 ± 0.4 mm) than during either an erect bicycle test (0.6 ± 0.4 mm) or treadmill exercise (0.7 ± 0.4 mm) (p <0.05). Supine posture should be considered as an important potentiator of exercise-induced myocardial ischemia whem comparing indicators such as electrocardiography, radionuclide ventriculography and thallium-201 myocardial perfusion imaging during exercise.