Association between activation of the renin-angiotensin system and secondary erythrocytosis in patients with chronic obstructive pulmonary disease

Optimization of cardiovascular risk factor management in patients with BCR::ABL1 negative chronic myeloproliferative neoplasms, current knowledge, and perspectives

The exact prognostic role of cardiovascular (CV) risk factors in patients with BCR::ABL1 negative chronic myeloproliferative neoplasms (MPNs) remains unknown as it is often masked by other MPN-related features that bear strong prognostic impact on thrombotic risk. Therefore, current MPN treatment is not primarily guided by presence of CV risk factors. Treatment of CV risk factors in MPN patients usually mirrors that from the general population, despite the fact that CV risk factors in MPNs have their own specificities. Moreover, the optimal target levels for different metabolic deflections in MPNs (i.e., low-density lipoprotein, serum uric acid, or glycated hemoglobin levels) have not been defined. In the current review, we separately discuss the most important aspects of every individual CV risk factor (arterial hypertension, hyperlipidemia, chronic kidney disease, smoking, diabetes mellitus, hyperuricemia, and obesity and cachexia) in MPNs, summarize recent advances in the field, and propose future directions and research areas which may be needed to appropriately manage CV risk factors in MPNs.

The contribution of the AT1 receptor to erythropoiesis

The renin-angiotensin system (RAS) comprises a broad set of functional peptides and receptors that play a role in cardiovascular homeostasis and contribute to cardiovascular pathologies. Angiotensin II (Ang II) is the most potent peptide hormone produced by the RAS due to its high abundance and its strong and pleiotropic impact on the cardiovascular system. Formation of Ang II takes place in the bloodstream and additionally in tissues in the so-called local RAS. Of the two Ang II receptors (AT1 and AT2) that Ang II binds to, AT1 is the most expressed throughout the mammalian body. AT1 expression is not restricted to cells of the cardiovascular system but in fact AT1 protein is found in nearly all organs, hence, Ang II takes part in several modulatory physiological processes one of which is erythropoiesis. In this review, we present multiple evidence supporting that Ang II modulates physiological and pathological erythropoiesis processes trough the AT1 receptor. Cumulative evidence indicates that Ang II by three distinct mechanisms influences erythropoiesis: 1) stimulation of renal erythropoietin synthesis; 2) direct action on bone marrow precursor cells; and 3) modulation of sympathetic nerve activity to the bone marrow. The text highlights clinical and preclinical evidence focusing on mechanistic studies using rodent models.

The Paradigm Shift from Polycythemia to Anemia in COPD: The Critical Role of the Renin-Angiotensin System Inhibitors

INTRODUCTION

Although polycythemia has been considered a common adverse event in COPD, anemia is reported more often and has gained more importance than polycythemia over the last thirty years.

AREAS COVERED

Factors considered to be associated with the development of anemia in COPD have included: Aging and kidney dysfunction with erythropoietin deficiency and bone marrow suppression due to uremic toxins; heart failure (HF), which is often encountered in COPD and is accompanied by anemia in one third of the cases; Low-grade chronic inflammation, which can directly suppresses the bone marrow and diminish iron absorption and utilization via increased hepcidin levels; long-term oxygen therapy (LTOT), which ameliorates chronic hypoxia, and most important, RAS inhibitors, which are widely used for the co-morbidities associated with COPD (hypertension, HF, CKD, diabetes) and have previously been shown to lower hematocrit values or cause anemia in various clinical conditions.

EXPERT OPINION

Introduction of LTOT in COPD and especially the established use of RAS inhibitors form the basis for the shift from polycythemia to anemia in COPD. Interestingly, when the SGLT2 inhibitors are introduced for cardiorenal protection in COPD, one could anticipate correction of anemia or even reemergence of polycythemia, since this new class of drugs can augment erythropoietin secretion and increase hematocrit values.

Risk Factors for Acute Coronary Syndrome in Upper Gastrointestinal Bleeding Patients

Background

Upper gastrointestinal bleeding (UGIB) is a common critical disease with a certain fatality rate. Acute coronary syndrome (ACS), another critical ill condition, is a regular occurrence in the UGIB. We identified risk factors for ACS in UGIB.

Methods

676 patients diagnosed with UGIB were enrolled retrospectively. We assessed the occurrence of ACS in UGIB patients and identified the risk factors for ACS by logistic regression analysis and random forest analysis.

Results

After propensity score matching (PSM), the ACS group (n = 69) and non-ACS group (n = 276) were analyzed. Logistic regression analysis showed that syncope (P = 0.001), coronary heart disease history (P = 0.001), Glasgow Blatchford score (P ≤ 0.001), Rockall risk score (P = 0.004), red blood cell distribution width (RDW) (P ≤ 0.001), total bilirubin (TBil) (P = 0.046), fibrinogen (P ≤ 0.001), and hemoglobin (P = 0.001) had important roles in ACS patients. With Mean Decrease Gini (MDG) sequencing, fibrinogen, RDW, and hemoglobin were ranked the top three risk factors associated with ACS. In ROC analysis, fibrinogen (AUC = 0.841, 95% CI: 0.779-0.903) and RDW (AUC = 0.826, 95% CI: 0.769-0.883) obtained good discrimination performance. According to sensitivity > 80%, the pAUC of fibrinogen and RDW were 0.077 and 0.101, respectively, and there was no significant difference (P = 0.326). However, according to specificity > 80%, the pAUC of fibrinogen was higher than that of RDW (0.126 vs. 0.088, P = 0.018).

Conclusion

Fibrinogen and RDW were important risk factors for ACS in UGIB. Additionally, combination with coronary heart disease, syncope, hemoglobin, and TBil played important roles in the occurrence of ACS. Meanwhile, it was also noted that Rockall score and Glasgow Blatchford score should be performed to predict the risk.

Anaemia and iron dysregulation: untapped therapeutic targets in chronic lung disease?

Hypoxia is common in many chronic lung diseases. Beyond pulmonary considerations, delivery of oxygen (O₂) to the tissues and subsequent O₂ utilisation is also determined by other factors including red blood cell mass and iron status; consequently, disruption to these mechanisms provides further physiological strains on an already stressed system. O₂ availability influences ventilation, regulates pulmonary blood flow and impacts gene expression throughout the body. Deleterious effects of poor tissue oxygenation include decreased exercise tolerance, increased cardiac strain and pulmonary hypertension in addition to pathophysiological involvement of multiple other organs resulting in progressive frailty. Increasing inspired O₂ is expensive, disliked by patients and does not normalise tissue oxygenation; thus, other strategies that improve O₂ delivery and utilisation may provide novel therapeutic opportunities in patients with lung disease. In this review, we focus on the rationale and possibilities for doing this by increasing haemoglobin availability or improving iron regulation.

Circulating Fibroblast Growth Factor-23 Levels are Associated with an Increased Risk of Anemia Development in Patients with Nondialysis Chronic Kidney Disease

Fibroblast growth factor-23 (FGF23) is an established biomarker of adverse outcomes in patients with chronic kidney disease (CKD). Several cross-sectional studies have suggested a possible association between FGF23 and anemia in these patients. In this large-scale prospective cohort study, we investigated this relationship and examined whether high FGF23 levels increase the risk of incident anemia. This prospective longitudinal study included 2,089 patients from the KoreaN cohort study for Outcome in patients With CKD. Anemia was defined as hemoglobin level <13.0 g/dl (men) and <12.0 g/dl (women). Log-transformed FGF23 significantly correlated with hepcidin but inversely correlated with iron profiles and hemoglobin. Multivariate logistic regression showed that log-transformed FGF23 was independently associated with anemia (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.04–1.24, P = 0.01). Among 1,164 patients without anemia at baseline, 295 (25.3%) developed anemia during a median follow-up of 21 months. In fully adjusted multivariable Cox models, the risk of anemia development was significantly higher in the third (hazard ratio [HR], 1.66; 95% CI, 1.11–2.47; P = 0.01) and fourth (HR, 1.84; 95% CI, 1.23–2.76; P = 0.001) than in the first FGF23 quartile. In conclusion, high serum FGF23 levels were associated with an increased risk for anemia in patients with nondialysis CKD.

Red cell distribution width associated with adverse cardiovascular outcomes in patients with chronic kidney disease

Background

Recent studies have demonstrated that red cell distribution width (RDW) is associated with cardiovascular (CV) events and mortality. Patients with chronic kidney disease (CKD) are often anemic and have high RDW levels. In this study, we investigated the effect of RDW on major composite CV outcomes among patients with CKD.

Methods

We retrospectively analyzed patients with CKD who were admitted to the department of cardiology of a tertiary hospital in 2011. The patients were divided into 2 groups: normal RDW (RDW < 14.5%) and elevated RDW (RDW ≥ 14.5%). Demographic characteristics, comorbidities, blood investigation results, prescriptions, and outcomes were analyzed after a 3-year follow-up period. Six adjustment levels were performed to evaluate the effect of RDW on outcomes.

Results

This study involved 282 patients with CKD: 213 in the elevated RDW group and 69 in the normal RDW group. The elevated RDW group had older patients, a lower proportion of male patients, lower left ventricular ejection fraction (LVEF) values, lower hemoglobin levels, lower serum albumin levels, and higher creatinine levels, compared with the normal RDW group. A linear trend was observed toward higher RDW in patients with deteriorating renal function. In the final adjusted model, RDW ≥ 14.5%, older age, and lower LVEF were associated with an increased risk of major composite CV outcomes.

Conclusion

RDW is a potentially useful cost-effective indicator of major composite CV outcomes in patients with CKD.

The impact of anaemia and iron deficiency in chronic obstructive pulmonary disease: A clinical overview

INTRODUCTION

Anaemia is increasingly recognised as an important comorbidity in the context of chronic obstructive pulmonary disease (COPD), but remains undervalued in clinical practice. This review aims to characterise the impact of anaemia and iron deficiency in COPD.

METHODS

Literature review of studies exploring the relationship between anaemia/iron deficiency and COPD, based on targeted MEDLINE and Google Scholar queries.

RESULTS

The reported prevalence of anaemia in COPD patients, ranging from 4.9% to 38.0%, has been highly variable, due to different characteristics of study populations and lack of a consensus on the definition of anaemia. Inflammatory processes seem to play an important role in the development of anaemia, but other causes (including nutritional deficiencies) should not be excluded from consideration. Anaemia in COPD has been associated with increased morbidity, mortality, and overall reduced quality of life. The impact of iron deficiency, irrespective of anaemia, is not as well studied, but it might have important implications, since it impacts production of red blood cells and respiratory enzymes. Treatment of anaemia/iron deficiency in COPD remains poorly studied, but it appears reasonable to assume that COPD patients should at least receive the same type of treatment as other patients.

CONCLUSIONS

Anaemia and iron deficiency continue to be undervalued in most COPD clinical settings, despite affecting up to one-third of patients and having negative impact on prognosis. Special efforts should be made to improve clinical management of anaemia and iron deficiency in COPD patients as a means of achieving better patient care.

The association of Red cell distribution width and in-hospital mortality in older adults admitted to the emergency department

BACKGROUND

The objective of the study was to test the hypothesis that elevated red cell distribution width (RDW) at admission increases the risk of mortality in older patients admitted to the emergency department (ED).

METHODS

We performed a retrospective analysis of patients admitted to the ED between May 2013 and October 2013. We included patients who were older than 65 years who visited the ED with any medical problems. Baseline RDW values were measured at the time of admission to the ED. The primary outcome was all-cause in-hospital mortality. Multivariate logistic analysis was performed.

RESULTS

A total of 1,990 patients were finally included in this study. The mean age was 75 years (SD 7), and 936 (47 %) subjects were male. The in-hospital mortality rate was 3.76 % (74 patients). RDW values higher in non-survivors than in survivors (15.9 ± 2.5 vs. 13.8 ± 1.7, p < 0.001). Multivariate logistic analysis showed that RDW was associated with all-cause in-hospital mortality after adjusting for other confounding factors.

DISCUSSION

RDW value at admission is an independent predictor of all-cause in-hospital mortality among patients older than 65 years. After adjustment for multiple confounders, the all-cause in-hospital mortality rate increased by 21.8% for each 1% increase in RDW.

CONCLUSION

These results show that RDW at admission is associated with in-hospital mortality among patients older than 65. Thus, RDW at admission may represent a surrogate marker of disease severity. We caution against using these findings to aid clinical decision-making process until they are externally validated.

High Fibroblast Growth Factor 23 Levels Associated With Low Hemoglobin Levels in Patients With Chronic Kidney Disease Stages 3 and 4

In chronic kidney disease (CKD), decreased erythropoietin production, low serum active vitamin D levels, and high renin-angiotensin-aldosterone activities had been regarded as major causes of renal anemia. At present, no clinical data are available to elucidate the association between renal anemia and fibroblast growth factor 23 (FGF23) levels in CKD. This study aimed to access whether FGF23 is involved in the pathogenesis of renal anemia. This cross-sectional observational study included 53 stable outpatients with CKD stages 3 and 4. Our primary predictor was serum FGF23 levels and outcome was hemoglobin levels. Measurements contained hemoglobin, FGF23, 25-hydroxyvitamin D, intact parathyroid hormone, plasma renin, serum aldosterone, HbA1C levels, lipid and iron profiles, and serum and urine electrolytes. Mean age of our patients was 66.4 ± 12.8 (SD) years, mean estimated glomerular filtration rate 33.5 ± 13.9 mL/min/1.73 m, median FGF23 level 200 (25th-75th percentile, 124-303) pg/mL, vitamin D level 19.5 (25th-75th percentile, 14.0-25.9) ng/mL, and hemoglobin level 12.7 (25th-75th percentile, 10.7-13.75) g/dL. Even after adjusting multiple variables, lower hemoglobin levels correlated significantly with FGF23 levels that were higher than the median value (>200 pg/mL). Moreover, after adjusting for aldosterone, but not 25-hydroxyvitamin D, it decreased the association with FGF23 that higher than median level and hemoglobin levels. We also observed a significant decrease of hemoglobin level in the higher FGF23 group who had a diabetes history. High FGF23 levels were observed to be associated with low hemoglobin levels, which may be partially mediated through the effects of serum aldosterone levels in our patients with CKD stages 3 and 4. Furthermore, we also presumed that diabetes itself may have an impact on the loop among FGF23, hemoglobin, and aldosterone levels in these CKD patients.

Renin-angiotensin system inhibitors linked to anemia: a systematic review and meta-analysis

BACKGROUND

The objective of this meta-analysis was to evaluate the risk of anemia in patients who received renin-angiotensin system (RAS) inhibitors.

METHODS

A literature search was performed using MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from inception through November, 2014. Studies that reported relative risks, odd ratios or hazard ratios comparing the anemia risk in patients who received angiotensin-converting-enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) vs. those who did not were included. We performed the prespecified sensitivity analysis including only only studies with confounder adjusted analysis. Pooled risk ratios (RRs) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method.

RESULTS

Seven studies (2 cohort and 5 cross-sectional studies) with 29,061 patients were included in the analysis to assess the risk of anemia and the RAS inhibitors use. The pooled RR of anemia in patients receiving ACEIs was 1.56 (95% CI, 1.40-1.73, I(2) = 17%). When meta-analysis was limited only to studies with confounder adjusted analysis, the pooled RR of anemia in patients using ACEIs was 1.57 (95% CI, 1.43-1.73, I(2) = 0%) The pooled RR of anemia in patients receiving ARBs was 1.60 (95% CI, 1.27-2.00, I(2) = 39%). The meta-analysis of studies with confounder adjusted analysis demonstrated the pooled RR of anemia in patients using ARBs of 1.59 (95% CI, 1.38-1.83, I(2) = 0%).

CONCLUSIONS

Our meta-analysis demonstrates an association between anemia and the use of RAS inhibitors. Hematological parameters should be monitored in patients treated with RAS inhibitors.

Anemia in Chronic obstructive pulmonary disease: Prevalence, pathogenesis, and potential impact

Chronic obstructive pulmonary disease (COPD) is a common preventable and treatable lifestyle-related disease with high global prevalence. COPD is associated with significant morbidity and mortality worldwide. Comorbidities are important events in the natural history of the disease and have a negative effect on the morbidity and mortality of COPD patients. Cardiac diseases, lung cancer, osteoporosis, and depression are common comorbidities reported for COPD. Recently, anemia has been recognized as a frequent comorbidity in COPD patients. The prevalence of anemia in patients with COPD varies from 7.5% to 33%. Anemia of chronic disease (ACD) is probably the most common type of anemia associated with COPD. ACD is driven by COPD-mediated systemic inflammation. Anemia in COPD is associated with greater healthcare resource utilization, impaired quality of life, decreased survival, and a greater likelihood of hospitalization. We need large prospective studies to discern the association between anemia and COPD.

Anaemia in chronic obstructive pulmonary disease: an insight into its prevalence and pathophysiology

Chronic obstructive pulmonary disease (COPD) is a major health problem, with increasing morbidity and mortality. There is a growing literature regarding the extra-pulmonary manifestations of COPD, which can have a significant impact on symptom burden and disease progression. Anaemia is one of the more recently identified co-morbidities, with a prevalence that varies between 4.9% and 38% depending on patient characteristics and the diagnostic criteria used. Systemic inflammation seems to be an important factor for its establishment and repeated bursts of inflammatory mediators during COPD exacerbations could further inhibit erythropoiesis. However, renal impairment, malnutrition, low testosterone levels, growth hormone level abnormalities, oxygen supplementation, theophylline treatment, inhibition of angiotensin-converting enzyme and aging itself are additional factors that could be associated with the development of anaemia. The present review evaluates the published literature on the prevalence and significance of anaemia in COPD. Moreover, it attempts to elucidate the reasons for the high variability reported and investigates the complex pathophysiology underlying the development of anaemia in these patients.

The association of red cell distribution width at hospital discharge and out-of-hospital mortality following critical illness*

OBJECTIVES

Red cell distribution width is associated with mortality and bloodstream infection risk in the critically ill. In hospitalized patients with critical illness, it is not known if red cell distribution width can predict subsequent risk of all-cause mortality following hospital discharge. We hypothesized that an increase in red cell distribution width at hospital discharge in patients who survived to discharge following critical care would be associated with increased postdischarge mortality.

DESIGN

Two-center observational cohort study

SETTING

: All medical and surgical ICUs at the Brigham and Women's Hospital and Massachusetts General Hospital.

PATIENTS

We studied 43,212 patients, who were 18 years old or older and received critical care between 1997 and 2007 and survived hospitalization.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The exposure of interest was red cell distribution width within 24 hours of hospital discharge and categorized a priori in quintiles as less than or equal to 13.3%, 13.3-14.0%, 14.0-14.7%, 14.7-15.8%, and more than 15.8%. The primary outcome was all-cause mortality in the 30 days following hospital discharge. Secondary outcomes included 90-day and 365-day mortality following hospital discharge. Mortality was determined using the U.S. Social Security Administration Death Master File, and 365-day follow-up was present in all cohort patients. Adjusted odds ratios were estimated by multivariable logistic regression models with inclusion of covariate terms thought to plausibly interact with both red cell distribution width and mortality. Adjustment included age, race, gender, Deyo-Charlson Index, patient type (medical vs surgical), sepsis, and number of organs with acute failure. In patients who received critical care and survived hospitalization, the discharge red cell distribution width was a robust predictor of all-cause mortality and remained so following multivariable adjustment. Patients with a discharge red cell distribution width of 14.0-14.7%, 14.7-15.8%, and more than 15.8% have an odds ratio for mortality in the 30 days following hospital discharge of 2.86 (95% CI, 2.25-3.62), 4.57 (95% CI, 3.66-5.72), and 8.80 (95% CI, 7.15-10.83), respectively, all relative to patients with a discharge red cell distribution width less than or equal to 13.3%. Following multivariable adjustment, patients with a discharge red cell distribution width of 14.0-14.7%, 14.7-15.8%, and more than 15.8% have an odds ratio for mortality in the 30 days following hospital discharge of 1.63 (95% CI, 1.27-2.07), 2.36 (95% CI, 1.87-2.97), and 4.18 (95% CI, 3.36-5.20), respectively, all relative to patients with a discharge red cell distribution width less than or equal to 13.3%. Similar significant robust associations post multivariable adjustments are seen with death by days 90 and 365 postdischarge. Estimating the receiver-operating characteristic area under the curve shows that discharge red cell distribution width has moderate discriminative power for mortality 30 days following hospital discharge (area under the curve = 0.70; SE 0.006; 95% CI, 0.69-0.71; p < 0.0001).

CONCLUSION

In patients treated with critical care who survive hospitalization, an elevated red cell distribution width at the time of discharge is a robust predictor of subsequent all-cause patient mortality. Increased discharge red cell distribution width likely reflects the presence of proinflammatory state, oxidative stress, arterial underfilling, or a combination, thereof which may explain the observed impact on patient survival following discharge. Elevated red cell distribution width at hospital discharge may identify ICU survivors who are at risk for adverse outcomes following hospital discharge.

Anaemia in chronic obstructive pulmonary disease. Does it really matter?

Chronic obstructive pulmonary disease (COPD) is one of the most prevalent chronic diseases, with an increasing rate in morbidity and mortality. In recent years, there has been a greater awareness about the clinical importance of systemic effects and other chronic conditions associated with COPD, as these significantly impact on the course of disease. The most studied extrapulmonary manifestations in COPD include the presence of concomitant cardiovascular disease, skeletal muscle wasting, osteoporosis and lung cancer. Anaemia is a recognised independent marker of mortality in several chronic diseases. Recent studies have shown that anaemia in patients with COPD may be more frequent than expected, with a prevalence ranging from 5% to 33%. Some evidence suggests that systemic inflammation may play an important pathogenic role, but anaemia in COPD is probably multifactorial and may be caused by others factors, such as concealed chronic renal failure, decreased androgenic levels, iron depletion, angiotensin-converting enzyme inhibitor treatment and exacerbations. Low levels of haemoglobin and haematocrit in COPD patients have been associated with poor clinical and functional outcomes as well as with mortality and increased healthcare costs. Despite the potential clinical benefit of successfully treating anaemia in these patients, evidence supporting the importance of its correction on the prognosis of COPD is uncertain.

Left ventricular hypertrophy in COPD without hypoxemia: the elephant in the room?

BACKGROUND

COPD is associated with significant cardiovascular mortality. Left ventricular hypertrophy (LVH) is a pivotal cardiovascular risk factor. The prevalence of LVH in COPD is currently unknown.

METHODS

We performed a pilot study of 93 normoxemic patients with COPD and 34 control subjects. Patients underwent echocardiography to measure left ventricular (LV) dimensions, ECG, measurement of serum B-type natriuretic peptide (BNP) levels, and 24-h BP recording. Spirometry and oxygen saturations were also recorded.

RESULTS

The oxygen saturations of patients with COPD were normal, at 96.5% (95% CI, 96.1%-97.0%), with a mean FEV(1) of 70.0% predicted (95% CI, 65.2%-74.8%). A total of 30.1% of patients with COPD met the echocardiographic criteria for LVH based on LV mass index, with more LVH in female patients than in male patients (43.2% vs 21.4%, P = .02). The LV mass index in patients with COPD was 96.2 g/m(2) (95% CI, 90.1-102.7 g/m(2)) vs 82.9 g/m(2) (95% CI, 75.8-90.6 g/m(2)) in control subjects ( P = .017). The LV mass index remained high in patients with COPD in the absence of a hypertension history (94.5 g/m(2) vs 79.9 g/m(2), P = .015) and with 24-h systolic BP <135 mm Hg (96.7 g/m(2) vs 82.5 g/m(2), P = .024). The LV ejection fraction (mean = 63.4%) and BNP (mean = 28.7 pg/mL) were normal in patients with COPD. The mean 24-h BP was normal in patients with COPD, at 125/72 mm Hg. ECG was less sensitive for detecting LVH than was echocardiography.

CONCLUSION

LVH with normal LV ejection fraction and BNP levels was present in a significant proportion of normotensive, normoxemic patients with COPD, especially female patients. Clinical trials are, therefore, indicated to evaluate treatments to regress LVH in patients with COPD.

A modern understanding of the traditional and nontraditional biological functions of angiotensin-converting enzyme

Angiotensin-converting enzyme (ACE) is a zinc-dependent peptidase responsible for converting angiotensin I into the vasoconstrictor angiotensin II. However, ACE is a relatively nonspecific peptidase that is capable of cleaving a wide range of substrates. Because of this, ACE and its peptide substrates and products affect many physiologic processes, including blood pressure control, hematopoiesis, reproduction, renal development, renal function, and the immune response. The defining feature of ACE is that it is composed of two homologous and independently catalytic domains, the result of an ancient gene duplication, and ACE-like genes are widely distributed in nature. The two ACE catalytic domains contribute to the wide substrate diversity of ACE and, by extension, the physiologic impact of the enzyme. Several studies suggest that the two catalytic domains have different biologic functions. Recently, the X-ray crystal structure of ACE has elucidated some of the structural differences between the two ACE domains. This is important now that ACE domain-specific inhibitors have been synthesized and characterized. Once widely available, these reagents will undoubtedly be powerful tools for probing the physiologic actions of each ACE domain. In turn, this knowledge should allow clinicians to envision new therapies for diseases not currently treated with ACE inhibitors.

Association of angiotensin-converting enzyme inhibitor therapy initiation with a reduction in hemoglobin levels in patients without renal failure

OBJECTIVE

To investigate whether treatment initiated with an angiotensin-converting enzyme inhibitor (ACE-I) or an angiotensin II receptor blocker (ARB) for patients with ischemic heart disease, hypertension, or diabetes causes a reduction in hemoglobin (Hb) levels.

PATIENTS AND METHODS

This was a retrospective cohort analysis using the computerized database of a large health maintenance organization. Included were all adults with a first purchase of an ACE-I, an ARB, or a calcium channel blocker (CCB) between January 1, 2004, and December 31, 2009, defined as the index date. Measures of Hb levels before and 1 year after the index date were reviewed, and the change was calculated. All the analyses were stratified by pharmaceutical class. The main exposure variables were the proportion of days covered (PDC) by these drugs and the mean enalapril dosage (for enalapril users only).

RESULTS

Levels of Hb before and after treatment were available for 14,754 patients taking ACE-Is, 751 taking ARBs, and 3087 taking CCBs. A high PDC was significantly associated with greater yearly reductions in Hb levels compared with a low PDC for CCB use, but was more pronounced for ACE-I and ARB use. A high PDC was also associated with a higher odds of developing anemia in ACE-I users (odds ratio [OR], 1.59; P<.001) and ARB users (OR, 2.21; P=.05). In nonanemic enalapril users, every 10-mg increment in daily dose was associated with an OR of 1.45 for the development of anemia (P<.001). The association remained after excluding nonadherent patients.

CONCLUSION

Levels of Hb are reduced during the first year of use of ACE-Is and to a lesser extent with use of ARBs. This association is dose dependent and is not explained by patient adherence.

Relation Between Red Cell Distribution Width and Severity of Coronary Artery Disease in Patients With Acute Myocardial Infarction

Increased red blood cell distribution width (RDW) has been associated with adverse outcomes in acute myocardial infarction (AMI). We evaluated the relationship between RDW and severity of coronary artery disease (CAD) in patients with AMI. We analyzed the relation between RDW and angiographic severity of CAD. Patients (n = 580) with elevated Syntax scores (SSs >32) had higher RDW values (15.1% ± 1.7% vs 14.1 ± 1.7%, P < .001). The SS was positively correlated with RDW level ( r = .252, P < .001) and neutrophil/lymphocyte (N/L) ratio ( r = .178, P < .001). There was a mild significant association between RDW level and N/L ratio ( r = .106, P = .033). In the multiple logistic regression analysis, RDW (odds ratio = 1.165, 95% confidence interval 1.02-1.32, P = .021) remained a significant predictor for the severity of CAD. Red blood cell distribution width, an inexpensive and easily measurable laboratory variable, is independently associated with the severity of CAD in patients with AMI.

Pulmonary Hypertension Secondary to COPD

The development of pulmonary hypertension in COPD adversely affects survival and exercise capacity and is associated with an increased risk of severe acute exacerbations. Unfortunately not all patients with COPD who meet criteria for long term oxygen therapy benefit from it. Even in those who benefit from long term oxygen therapy, such therapy may reverse the elevated pulmonary artery pressure but cannot normalize it. Moreover, the recent discovery of the key roles of endothelial dysfunction and inflammation in the pathogenesis of PH provides the rationale for considering specific pulmonary vasodilators that also possess antiproliferative properties and statins.

Angiotensin II infusion induces marked diaphragmatic skeletal muscle atrophy

Advanced congestive heart failure (CHF) and chronic kidney disease (CKD) are characterized by increased angiotensin II (Ang II) levels and are often accompanied by significant skeletal muscle wasting that negatively impacts mortality and morbidity. Both CHF and CKD patients have respiratory muscle dysfunction, however the potential effects of Ang II on respiratory muscles are unknown. We investigated the effects of Ang II on diaphragm muscle in FVB mice. Ang II induced significant diaphragm muscle wasting (18.7±1.6% decrease in weight at one week) and reduction in fiber cross-sectional area. Expression of the E3 ubiquitin ligases atrogin-1 and muscle ring finger-1 (MuRF-1) and of the pro-apoptotic factor BAX was increased after 24 h of Ang II infusion (4.4±0.3 fold, 3.1±0.5 fold and 1.6±0.2 fold, respectively, compared to sham infused control) suggesting increased muscle protein degradation and apoptosis. In Ang II infused animals, there was significant regeneration of injured diaphragm muscles at 7 days as indicated by an increase in the number of myofibers with centralized nuclei and high expression of embryonic myosin heavy chain (E-MyHC, 11.2±3.3 fold increase) and of the satellite cell marker M-cadherin (59.2±22.2% increase). Furthermore, there was an increase in expression of insulin-like growth factor-1 (IGF-1, 1.8±0.3 fold increase) in Ang II infused diaphragm, suggesting the involvement of IGF-1 in diaphragm muscle regeneration. Bone-marrow transplantation experiments indicated that although there was recruitment of bone-marrow derived cells to the injured diaphragm in Ang II infused mice (267.0±74.6% increase), those cells did not express markers of muscle stem cells or regenerating myofibers. In conclusion, Ang II causes marked diaphragm muscle wasting, which may be important for the pathophysiology of respiratory muscle dysfunction and cachexia in conditions such as CHF and CKD.

Red cell distribution width in patients with prehypertension and hypertension

OBJECTIVE

Red cell distribution width (RDW) which is reported as part of complete blood count in routine clinical practice, is a measure of variability in size of the erythrocytes in the circulation. It is a novel predictor of mortality both in unselected populations and in some selected group of patients. We aimed to search whether RDW values differ between the healthy population and the patients with pre-hypertension and hypertension who are otherwise healthy, considering the widely accepted role of RDW as a prognostic marker especially for mortality.

PATIENTS AND METHODS

Patients who were diagnosed with prehypertension or hypertension for the first time according to the Joint National Committee (JNC) 7 criteria and otherwise healthy were enrolled to the study. One-hundred and twenty-eight patients with hypertension, 74 patients with prehypertension and 36 healthy controls participated in the study. Complete blood count, biochemistry and erythrocyte sedimentation rates were measured by standard methods. Hemoglobin, white blood cell count, mean corpuscular volume, platelet count and RDW were recorded.

RESULTS

After adjustment for age, hemoglobin level, presence of anemia, serum uric acid level, erythrocyte sedimentation rate and mean corpuscular volume, mean RDW values were 15.26 ± 0.82, 16.54 ± 0.91 and 13.87 ± 0.94 in prehypertensive, hypertensive and control groups, respectively (p < 0.05). Systolic and diastolic blood pressures were strongly correlated with RDW (r = 0.848 and r = 0.748, respectively; p < 0.01).

CONCLUSION

RDW is higher in prehypertensive and hypertensive patients compared with healthy controls independently of age, inflammatory status and anemia. Higher RDW values are strongly correlated with higher systolic and diastolic blood pressures.

Red cell distribution width and all-cause mortality in critically ill patients

OBJECTIVE

Red cell distribution width is a predictor of mortality in the general population. The prevalence of increased red cell distribution width and its significance in the intensive care unit are unknown. The objective of this study was to investigate the association between red cell distribution width at the initiation of critical care and all cause mortality.

DESIGN

Multicenter observational study.

SETTING

Two tertiary academic hospitals in Boston, MA.

PATIENTS

A total of 51,413 patients, aged ≥ 18 yrs, who received critical care between 1997 and 2007.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The exposure of interest was red cell distribution width as a predictor of mortality in the general population. The prevalence of increased red cell distribution width and its significance in the intensive care unit are unknown and categorized a priori in quintiles as ≤ 13.3%, 13.3% to 14.0%, 14.0% to 14.7%, 14.7% to 15.8%, and >15.8%. Logistic regression examined death by days 30, 90, and 365 postcritical care initiation, inhospital mortality, and bloodstream infection. Adjusted odds ratios were estimated by multivariable logistic regression models. Adjustment included age, sex, race, Deyo-Charlson index, coronary artery bypass grafting, myocardial infarction, congestive heart failure, hematocrit, white blood cell count, mean corpuscular volume, blood urea nitrogen, red blood cell transfusion, sepsis, and creatinine. Red cell distribution width was a particularly strong predictor of all-cause mortality 30 days after critical care initiation with a significant risk gradient across red cell distribution width quintiles after multivariable adjustment: red cell distribution width 13.3% to 14.0% (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.08-1.30; p <.001); red cell distribution width 14.0% to 14.7% (OR, 1.28; 95% CI, 1.16-1.42; p <.001); red cell distribution width 14.7% to 15.8% (OR, 1.69; 95% CI, 1.52-1.86; p <.001); red cell distribution width >15.8% (OR, 2.61; 95% CI, 2.37-2.86; p <.001), all relative to patients with red cell distribution width ≤ 13.3%. Similar significant robust associations postmultivariable adjustments are seen with death by days 90 and 365 postcritical care initiation as well as inhospital mortality. In a subanalysis of patients with blood cultures drawn (n = 18,525), red cell distribution width at critical care initiation was associated with the risk of bloodstream infection and remained significant after multivariable adjustment. The adjusted risk of bloodstream infection was 1.40- and 1.44-fold higher in patients with red cell distribution width values in the 14.7% to 15.8% and >15.8% quintiles, respectively, compared with those with red cell distribution width ≤ 13.3%. Estimating the receiver operating characteristic area under the curve shows that red cell distribution width has moderate discriminative power for 30-day mortality (area under the curve = 0.67).

CONCLUSION

Red cell distribution width is a robust predictor of the risk of all-cause patient mortality and bloodstream infection in the critically ill. Red cell distribution width is commonly measured, inexpensive, and widely available and may reflect overall inflammation, oxidative stress, or arterial underfilling in the critically ill.

The role of the renin-angiotensin system in the regulation of erythropoiesis

The renin-angiotensin system is the major regulator of blood pressure by virtue of controlling vascular resistance and plasma volume. Much less recognition exists for the role of the renin-angiotensin system in regulating erythropoiesis, a biological function critical for oxygen delivery to tissues. In this review, we present evidence that angiotensin II (Ang II) is a physiologically important regulator of erythropoiesis with 2 key actions. First, Ang II is a growth factor of erythroid progenitors and, in cooperation with erythropoietin, increases red blood cell mass. Second, Ang II acts as an erythropoietin secretagogue to maintain increased erythropoietin levels despite increments in hematocrit. Among a multitude of physiologic and pathophysiologic implications, these lines of evidence provide an explanation for the effect of angiotensin-converting enzyme inhibitors and Ang II type 1 receptor blockers to decrease hematocrit or cause anemia in various clinical conditions.

Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension

This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.

[High frequency of anemia in COPD patients admitted in a tertiary hospital]

INTRODUCTION

Anemia is related to chronic and inflammatory diseases. Moreover, it is a factor of worse outcome in heart failure or myocardial infarction. Despite the importance of hemoglobin as a globular oxygen carrying protein, there are few studies on anemia and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To determine the frequency and the characteristics of the anemia in COPD patients admitted to a tertiary hospital within a one year period.

METHODS

Anthropometric and clinical data, tobacco habit, lung function tests, arterial blood gases and a basic study of anemia (BSA) were collected from digital clinical files.

RESULTS

A total of 177 patients were enrolled. Mean age was 70 (range 44-95), FEV1 was 35 (15%) and hemoglobin (Hb) 136(22) g/dl. Sixty-six (37%) patients had chronic respiratory failure (CRF) and 59 (33%) were receiving long-term oxygen therapy. A total of 56 (31%) had anemia (Hb < 130 g/dl in men or < 120 g/dl in women) with a mean Hb of 111(13). Anemia was normocytic normochromic in 32 cases (58%). BSA was obtained in 24 patients (42.85%) and showed that 10 patients (41%) had anemia of chronic disease, 6 patients (25%) had iron deficiency and 8 (34%) had other causes. It should be mentioned that 35 patients (53%) had CRF had anemia but only 8 patients had erythrocytosis (4.5%).

CONCLUSION

Anemia was frequent in these patients and was an underdiagnosed comorbidity.

Treatment of chronic mountain sickness: critical reappraisal of an old problem

A review is made on the different treatment strategies essayed to date in the management of chronic mountain sickness (CMS). After a brief presentation of the epidemiology and of the pathophysiological mechanisms proposed for explaining the disease, the advantages and drawbacks of the different treatment approaches are discussed, along with their pathopysiological rationale. A particular emphasis is dedicated to the scientific foundations underlying the development of acetazolamide and angiotensin-converting enzyme inhibitors as promising therapeutic agents for CMS, as well as the clinical evidence existing so far on their usefulness in the treatment of CMS. Various methodological issues that need to be addressed in future clinical studies on efficacy of therapies for CMS are discussed. There is also a brief discussion on potential treatment options for chronic high altitude pulmonary hypertension. Closing remarks on the need of taking increasingly into account the development and implementation of preventive measures are made.

Anemia in COPD: Should It Be Taken Into Consideration?

Recent recognition of the importance of nonpulmonary signs and symptoms in the management and prognosis of chronic obstructive pulmonary disease (COPD) has led to a shift in the focus of diagnostic and therapeutic strategies to encompass these aspects. We no longer concentrate on assessing a single functional variable (forced expiratory volume in 1 second) as a predictor of survival in these patients. Most of the research undertaken to date into COPD-related systemic disorders has targeted weight loss, muscular dysfunction, osteoporosis, and cardiovascular disease. However, the abnormal inflammatory response associated with COPD may provoke other disorders such as anemia. Moreover, comorbid anemia has been shown to be an independent predictor of mortality in several chronic diseases including cancer and heart failure. Anemia is, therefore, an entity that should be taken into consideration in the overall management of respiratory disease because it may have a clear detrimental impact on various aspects of the patient s health, including dyspnea, exercise tolerance, and quality of life. There is a growing body of literature on the relationship between anemia and COPD. Our aim is to briefly review the pathophysiologic aspects of this association before going on to discuss some of the most recent evidence published.

Angiotensin-converting enzyme inhibitors slow recovery from anemia following cardiac surgery

OBJECTIVES

Angiotensin-converting enzyme (ACE) inhibitors, which are frequently administered in patients with heart disease, have a known inhibitory effect on erythropoiesis. The aim of this study was to detect whether early ACE inhibitor administration slows recovery from anemia following recent cardiac surgery.

METHODS AND RESULTS

Forty male patients with anemia (hemoglobin < 12 g/dL) an average of 9 days after cardiac surgery were randomized to receive enalapril (ACE inhibitor group) or not. All of the patients received ferrous sulfate, 525 mg, in addition to standard therapy. Patients with anemia due to other causes were excluded. Blood samples were obtained at baseline, and after 8 days, 16 days, and 60 days. A 6-min walking test and echocardioscan were performed at baseline, and after 16 days and 60 days of treatment, and a chest radiograph was obtained at baseline and after 60 days. The ACE inhibitor group showed a statistically significant lower increase in hemoglobin and RBC values. The peak between-group differences of 1 g/dL of hemoglobin (p = 0.012) and 444 RBCs per milliliter (p = 0.017) were observed on day 16.

CONCLUSIONS

Early enalapril maleate administration in anemic patients after heart surgery significantly inhibits erythropoiesis. This unfavorable effect on anemia should be considered when prescribing ACE inhibitors for such patients.

Synthesis, binding studies and in vivo biological evaluation of novel non-peptide antihypertensive analogues

AT(1) antagonists (SARTANs) constitute the last generation of drugs for the treatment of hypertension, designed and synthesized to mimic the C-terminal segment of the vasoconstrictive hormone angiotensin II (AngII). They exert their action by blocking the binding of AngII on the AT(1) receptor. Up to date eight AT(1) antagonists have been approved for the regulation of high blood pressure. Although these molecules share common structural features and are designed to act under the same mechanism, they have differences in their pharmacological profiles and antihypertensive efficacy. Thus, there is still a need for novel analogues with better pharmacological and financial profiles. An example of a novel synthetic non peptide AT(1) antagonist which devoids the classical template of SARTANs is MM1. In vivo studies showed that MMK molecules, which fall in the same class of MM1, had a significant antihypertensive (40-80% compared to the drug losartan) activity. However, in vitro affinity studies showed that losartan has considerably higher affinity. The theoretical docking studies showed that MM1 acts on the same site of the receptor as losartan. They exert hydrophobic interactions with amino acid Val108 of the third helix of the AT(1) receptor and other hydrophobic amino acids in spatial vicinity. In addition, losartan favours multiple hydrogen bondings between its tetrazole group with Lys199. These additional interactions may in part explain its higher in vitro binding affinity.

Neurohumoral activation as a link to systemic manifestations of chronic lung disease

COPD is a major cause of death and disability worldwide. Treatment of COPD improves lung function but is unlikely to slow the steady downhill course of the disease or reduce mortality. In COPD, numerous abnormalities can be found outside the lung. These include systemic inflammation, cachexia, and skeletal muscle dysfunction. Thus, COPD has been called a systemic disease. Convincing data demonstrate that COPD causes neurohumoral activation. By precedents derived from chronic heart failure and other diseases characterized by neurohumoral activation, we propose that the negative consequences of neurohumoral activation, namely inflammation, cachexia, effects on ventilation, and skeletal muscle dysfunction, give rise to a self-perpetuating cycle that contributes to the pathogenesis of COPD, and which may involve respiratory muscle dysfunction as well as systemic inflammation. This concept may further help explain the increased cardiovascular morbidity and mortality in COPD patients. Currently, little is known about the effect of treatments directed at neurohumoral activation and COPD. As this aspect of COPD becomes better understood, new insights may direct novel therapeutic approaches.

Comparative effects of fosinopril and irbesartan on hematopoiesis in essential hypertensives

OBJECTIVE

To compare the response of erythropoiesis to an angiotensin receptor blocker, irbesartan with an angiotensin conversing enzyme inhibitor, fosinopril, in essential hypertensive patients with normal renal function.

DESIGN AND METHODS

Thirty patients were randomized to receive either irbesartan (150 mg once daily) (n = 15, mean age 65.2+/-8.7 years) or fosinopril (20 mg once daily) (n = 15, mean age 57.4+/-11.5 years, difference is not significant) during 12 weeks. Plasma erythropoietin, hemoglobin (Hb) and hematocrit (Hc) levels were measured at start and monthly after receiving the treatment. All values are expressed as mean+/-1SD.

RESULTS

Irbesartan decreased erythropoietin levels (baseline 20.7+/-1.3 vs. 18.1+/-3.7 mU/mL, p=0.019), but they remained unchanged with fosinopril (baseline 18.8+/-1.3 vs. 18.6+/-1.6 mU/mL). Hb levels lowered in irbesartan group (baseline 13.8+/-1.2 vs. 13.5+/-1.1 g/dL, p=0.029), but they did not change in fosinopril-treated patients (baseline 14.6+/-1.3 vs. 14.5+/-1.3 g/dL). Hc did not show any change neither in irbesartan group (baseline 40.9+/-3.7 vs. 40.8+/-3.3 %) nor in fosinopril group (baseline 14.6+/-1.3 vs. 14.5+/-1.3 %).

CONCLUSIONS

Irbesartan lowered erythropoietin secretion and hemoglobin levels in essential hypertensives. Fosinopril can neither influence erythropoietin secretion nor decrease hemoglobin levels. Angiotensin receptor blockers seem to get higher efficacy for antagonism angiotensin effects. Safety of angiotensin receptor blockers in anemic hypertensive patients should be studied.

Role of the renin-angiotensin system in primitive erythropoiesis in the chick embryo

Inactivation of the gene encoding mouse angiotensin I-converting enzyme (ACE), which converts angiotensin I into angiotensin II, results in anemia in adult animals. This anemia is corrected by angiotensin II, demonstrating the involvement of angiotensin II in adult (definitive) erythropoiesis. We investigated the possible role of the renin-angiotensin system (RAS) in primitive erythropoiesis in the yolk sac of the chicken embryo. Enzymatically active ACE was detected in the yolk sac endoderm, concomitantly with the differentiation of blood islands in the adjacent yolk sac mesoderm. The simultaneous presence of all the other components of the RAS (renin, angiotensinogen, angiotensin II receptor) in the vicinity of the blood islands suggests that this system is involved in erythropoiesis. This role was confirmed by in vivo blockade of the RAS with fosinoprilate, a specific inhibitor of chicken ACE, which decreased hematocrit by 15%. A similar decrease in hematocrit was observed following treatment with the angiotensin II receptor antagonist Sar1-Ile8-Angiotensin II, suggesting that this effect was mediated by angiotensin II. Both treatments affected hematocrit by decreasing erythroblast proliferation. Thus, the RAS, and its effector peptide angiotensin II in particular, modulates primitive erythropoiesis.

Apoptotic mechanisms in the control of erythropoiesis

Erythropoiesis is a complex multistep process encompassing the differentiation of hemopoietic stem cells to mature erythrocytes. The steps involved in this complex differentiation process are numerous and involve first the differentiation to early erythoid progenitors (burst-forming units-erythroid, BFU-E), then to late erythroid progenitors (colony-forming units-erythroid) and finally to morphologically recognizable erythroid precursors. A key event of late stages of erythropoiesis is nuclear condensation, followed by extrusion of the nucleus to produce enucleated reticulocytes and finally mature erythrocytes. During the differentiation process, the cells became progressively sensitive to erythropoietin that controls both the survival and proliferation of erythroid cells. A normal homeostasis of the erythropoietic system requires an appropriate balance between the rate of erythroid cell production and red blood cell destruction. Growing evidences outlined in the present review indicate that apoptotic mechanism play a relevant role in the control of erythropoiesis under physiologic and pathologic conditions. Withdrawal of erythropoietin or stimulation of death receptors such as Fas or TRAIL-Rs leads to activation of a subset of caspase-3, -7 and -8, which then cleave the transcription factors GATA-1 and TAL-1 and trigger apoptosis. In addition, there is evidence that a number of caspases are physiologically activated during erythroid differentiation and are functionally required for erythroid maturation. Several caspase substrates are cleaved in differentiating cells, including the protein acinus whose activation by cleavage is required for chromatin condensation. The studies on normal erythropoiesis have clearly indicated that immature erythroid precursors are sensitive to apoptotic triggering mediated by activation of the intrinsic and extrinsic apoptotic pathways. These apoptotic mechanisms are frequently exacerbated in some pathologic conditions, associated with the development of anemia (ie, thalassemias, multiple myeloma, myelodysplasia, aplastic anemia). The considerable progress in our understanding of the apoptotic mechanisms underlying normal and pathologic erythropoiesis may offer the way to improve the treatment of several pathologic conditions associated with the development of anemia.

Towards the understanding of the local hematopoietic bone marrow renin-angiotensin system

The classical view of the renin-angiotensin system (RAS) as a circulating endocrine system has evolved to organ- and tissue-based systems that perform paracrine/autocrine functions. Angiotensin II (Ang II), the dominant effector peptide of the RAS, regulates cellular growth in a wide variety of tissues in (patho)biological states. In 1996, we hypothesized that there exists a locally active RAS in the bone marrow affecting the growth, production, proliferation and differentiation of hematopoietic cells. Evidences supporting this hypothesis are growing. Ang II, through interacting with Ang II type 1 (AT1) receptor stimulates erythroid differentiation. This stimulatory effect of Ang II on erythropoiesis was completely abolished by a specific AT1 receptor antagonist, losartan. AT1a receptors are present on human CD34(+) hematopoietic stem cells. Ang II increases hematopoietic progenitor cell proliferation and this effect was also blocked by losartan. Angiotensin-converting enzyme (ACE) is involved in enhancing the recruitment of primitive stem cells into S-phase in hematopoietic bone marrow by degrading tetrapeptide AcSDKP. ACE inhibitors modified the circulating hematopoietic progenitors in healthy subjects. RAS may also affect pathological/neoplastic hematopoiesis. Renin has been isolated from leukemic blast cells. Higher bone marrow ACE levels in acute leukemic patients suggested that ACE is produced at higher quantities in the leukemic bone marrow. In this review, the 'State of the Art' of the local bone marrow RAS is summarized. A local RAS in the bone marrow can mediate, in an autocrine/paracrine fashion, some of the principal steps of hematopoietic cell production. To show a causal link between the components of RAS and the other regulatory hematopoietic growth factors is not only an academic curiosity. Elucidation of such a local bone marrow system may offer novel therapeutic approaches in pathologic/neoplastic conditions.