Publications of the Space Physiology and Countermeasures Program, Cardiopulmonary Discipline: 1980-1990

A 10-year cumulative bibliography of publications resulting from research supported by the Cardiopulmonary Discipline of the Space Physiology and Countermeasures Program of NASA's Life Sciences Division is provided. Primary subjects included in this bibliography are Fluid Shifts, Cardiovascular Fitness, Cardiovascular Physiology, and Pulmonary Physiology. General physiology references are also included. Principal investigators whose research tasks resulted in publication are identified. Publications are identified by a record number corresponding with their entry in the Life Sciences Bibliographic Database, maintained at the George Washington University

ACUTE AND PROLONGED EFFECT OF NEW TREATMENTS (LEVOSIMENDAN AND SACUBITRIL/VALSARTAN) IN HEART FAILURE: AN HOLISTIC EVALUATION

Alveolar-capillary membrane evaluated by carbon monoxide diffusion (DLCO) plays an important role in heart failure (HF). Surfactant Proteins (SPs) have also been suggested as a worthwhile marker. In acute HF, Levosimendan improves pulmonary hemodynamics and reduces lung fluids but associated SPs and DLCO changes are unknown. Sixty-five acute HF patients underwent spirometry, cardiopulmonary exercise test (CPET) and SPs determination before and after Levosimendan. Levosimendan caused natriuretic peptide-B (BNP) reduction, peakVO2 increase and VE/VCO2 slope reduction. Spirometry improved but DLCO did not. SP-A, SP-D and immature SP-B reduced (73.7\u202f\ub1\u202f25.3 vs. 66.3\u202f\ub1\u202f22.7\u202fng/mL*, 247\u202f\ub1\u202f121 vs. 223\u202f\ub1\u202f110\u202fng/mL*, 39.4\u202f\ub1\u202f18.7 vs. 34.4\u202f\ub1\u202f17.9AU*, respectively); while mature SP-B increased (424\u202f\ub1\u202f218 vs. 461\u202f\ub1\u202f243\u202fng/mL, *\u202f=\u202fp\u202f<\u202f0.001). Spirometry, BNP and CPET changes suggest hemodynamic improvement and lung fluid reduction. SP-A, SP-D and immature SP-B reduction indicates a reduction of inflammatory stress; conversely mature SP-B increase suggests alveolar cell function restoration. In conclusion, acute lung fluid reduction is associated with SPs but not DLCO changes. SPs are fast responders to alveolar-capillary membrane condition changes. On the other hand, regarding chronic heart failure, Sacubitril/Valsartan represents a novel therapy in the treatment of chronic heart failure with reduced ejection fraction (HFrEF), has recently proved efficacy in improving exercise tolerance and cardiac performance. We enrolled a cohort of HFrEF outpatients eligible for sacubitril/valsartan and performed serial cardiopulmonary exercise tests (CPET), pulmonary function tests, laboratory and echocardiographic assessments before and during the gradual titration of this treatment, in order to evaluate its effects on cardiopulmonary function and left ventricular remodeling. In this interim analysis, we examined twenty-five patients treated with sacubitril/valsartan for at three months. At a mean follow-up of 169\ub174 days, 92% of patients reached the maximum dose, without important safety concerns. Ejection fraction increased (31.0\ub15.4 vs. 37.2\ub19.6 %; p=0.009), while left ventricular end-diastolic and end-systolic volumes decreased (respectively, 116.8\ub131.4 vs. 90.5\ub121.3 ml, p=0.011; 80.9\ub124.5 vs. 58.2\ub121.4 ml, p=0.004). Peak oxygen consumption (VO2) improved from 63.4\ub112.5 to 70.3\ub113.3 % of predicted (p=0.002), along with workload at maximal exercise (97.0\ub139.3 vs. 103.7\ub139.7 watt, p=0.001) and VO2 at the anaerobic threshold (881\ub1278 to 1056\ub1350 ml, p=0.012). Minute ventilation/carbon dioxide production relationship (VE/VCO2 slope) did not reach statistical significance in this sub-population. New York Heart Association functional class improved (p=0.004), together with a significant decrease of MECKI (Metabolic Exercise test data combined with Cardiac and Kidney Indexes) score from 3.0 (IQR 1.7-6.3) to 1.8 (0.8-3.6) %, with a positive impact on two-year HF prognosis (p=0.009).In conclusion medium-term treatment with sacubitril/valsartan demonstrated beneficial effects on exercise tolerance, left ventricular remodelling and functional status, confirming the results from previous clinical trials in real-life. The longer follow-up and larger population of the finished study will further contribute to the assessment of its positive effects on HF patients

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 164

This bibliography lists 275 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1977

Progress in Hemodialysis

Hemodialysis (HD) represents the first successful long-term substitutive therapy with an artificial organ for severe failure of a vital organ. Because HD was started many decades ago, a book on HD may not appear to be up-to-date. Indeed, HD covers many basic and clinical aspects and this book reflects the rapid expansion of new and controversial aspects either in the biotechnological or in the clinical field. This book revises new technologies and therapeutic options to improve dialysis treatment of uremic patients. This book consists of three parts: modeling, methods and technique, prognosis and complications

The characterisation of growth hormone-related cardiac disease with magnetic resonance imaging & The effects of growth hormone dysregulation on adenosine monophosphate-activated protein kinase in cardiac tissue

PhDChronic growth hormone (GH) excess, acromegaly, causes a specific cardiomyopathy, which remains poorly understood. The pattern of hypertrophy is distinct from other forms of cardiac disease and begins to appear before hypertension or diabetes. GH deficiency (GHD) also causes cardiovascular problems, with reduced ability to mount a cardiovascular response to exercise. Acromegaly and GHD patients have increased cardiac mortality. Cardiac magnetic resonance imaging (CMR) is the gold standard for assessment of cardiac mass and provides data on cardiac function, fibrosis, valve function and ischaemia. This study used CMR to assess 23 patients with acromegaly or GHD, before and after treatment of their GH disorder, and 23 healthy controls. Patients with acromegaly demonstrated increased left ventricular mass index (LVMi), end diastolic volume index, stroke volume index and cardiac index, which persisted at one year, despite treatment of underlying disease. Patients with GHD demonstrated LVMi at the bottom (males) or beneath (females) published normal references ranges, which increased with one year of GH replacement. The mechanisms by which GH influences cardiac tissue are poorly understood. Adenosine monophosphate-activated protein kinase (AMPK) is an energy-regulator enzyme, which interacts with several metabolic hormones. Mutations in AMPK cause arrhythmias and cardiac hypertrophy. AMPK activation may be a mechanism by which GH causes some of its cardiac effects. This study used primary cardiomyocytes and mouse and rat models of GH excess and deficiency to study the effects of GH on cardiac AMPK. Acute GH treatment increased AMPK activity in both in vivo and in vitro studies; acute IGF-I treatment had the opposite effect. In 2 and 8 month old bovine GH-overexpressing (bGH) and GH receptor knock out (GHRKO) mice, functional AMPK assay did not demonstrate any difference in cardiac AMPK activity between transgenics and controls. However, Western blotting for Threonine-172 phospho (p)AMPK levels, a marker of AMPK activity, demonstrated increased cardiac pAMPK in 2 month old bGH mice and a reduction in cardiac pAMPK levels in 8 month old animals. A trend towards the same findings was seen in GHRKO mice. This indicates that both GH and IGF-I interact with myocardial AMPK, apparently via different mechanisms

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 197, September 1979

This bibliography lists 193 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1979

Separator fluid volume requirements in multi-infusion settings

INTRODUCTION. Intravenous (IV) therapy is a widely used method for the administration of medication in hospitals worldwide. ICU and surgical patients in particular often require multiple IV catheters due to incompatibility of certain drugs and the high complexity of medical therapy. This increases discomfort by painful invasive procedures, the risk of infections and costs of medication and disposable considerably. When different drugs are administered through the same lumen, it is common ICU practice to flush with a neutral fluid between the administration of two incompatible drugs in order to optimally use infusion lumens. An important constraint for delivering multiple incompatible drugs is the volume of separator fluid that is sufficient to safely separate them. OBJECTIVES. In this pilot study we investigated whether the choice of separator fluid, solvent, or administration rate affects the separator volume required in a typical ICU infusion setting. METHODS. A standard ICU IV line (2m, 2ml, 1mm internal diameter) was filled with methylene blue (40 mg/l) solution and flushed using an infusion pump with separator fluid. Independent variables were solvent for methylene blue (NaCl 0.9% vs. glucose 5%), separator fluid (NaCl 0.9% vs. glucose 5%), and administration rate (50, 100, or 200 ml/h). Samples were collected using a fraction collector until <2% of the original drug concentration remained and were analyzed using spectrophotometry. RESULTS. We did not find a significant effect of administration rate on separator fluid volume. However, NaCl/G5% (solvent/separator fluid) required significantly less separator fluid than NaCl/NaCl (3.6 ± 0.1 ml vs. 3.9 ± 0.1 ml, p <0.05). Also, G5%/G5% required significantly less separator fluid than NaCl/NaCl (3.6 ± 0.1 ml vs. 3.9 ± 0.1 ml, p <0.05). The significant decrease in required flushing volume might be due to differences in the viscosity of the solutions. However, mean differences were small and were most likely caused by human interactions with the fluid collection setup. The average required flushing volume is 3.7 ml. CONCLUSIONS. The choice of separator fluid, solvent or administration rate had no impact on the required flushing volume in the experiment. Future research should take IV line length, diameter, volume and also drug solution volumes into account in order to provide a full account of variables affecting the required separator fluid volume

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 401)

This bibliography lists 140 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during May 1995. Subject coverage includes: aerospace medicine, behavioral sciences, man/system technology and life support, and space biology