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PubMed2001

Orientation illusions and heart-rate changes during short-radius centrifugation.

Intermittent short-radius centrifugation is a promising countermeasure against the adverse effects of prolonged weightlessness. To assess the feasibility of this countermeasure, we need to understand the disturbing sensory effects that accompany some movements carried out during rotation. We tested 20 subjects who executed yaw and pitch head movements while rotating at constant angular velocity. They were supine with their main body axis perpendicular to earth gravity. The head was placed at the centrifuge's axis of rotation. Head movements produced a transient elevation of heart-rate. All observers reported head-contingent sensations of body tilt although their bodies remained supine. Mostly, the subjective sensations conform to a model based on semicircular canal responses to angular acceleration. However, some surprising deviations from the model were found. Also, large inter-individual differences in direction, magnitude, and quality of the illusory body tilt were observed. The results have implications for subject screening and prediction of subjective tolerance for centrifugation.

Adult↗
PubMed2002

A rapid single-step centrifugation method for determination of HDL, LDL, and VLDL cholesterol, and TG, and identification of predominant LDL subclass.

Determination of the circulating levels of plasma lipoproteins HDL, LDL, and VLDL is critical in the assessment of risk of coronary heart disease. More recently it has become apparent that the LDL subclass pattern is a further important diagnostic parameter. The reference method for separation of plasma lipoproteins is ultracentrifugation. However, current methods often involve prolonged centrifugation steps and use high salt concentrations, which can modify the lipoprotein structure and must be removed before further analysis. To overcome these problems we have now investigated the use of rapid self-generating gradients of iodixanol for separation and analysis of plasma lipoproteins. A protocol is presented in which HDL, LDL, and VLDL, characterized by electron microscopy and agarose gel electophoresis, separate in three bands in a 2.5 h centrifugation step. Recoveries of cholesterol and TG from the gradients were close to 100%. The distribution profiles of cholesterol and TG in the gradient were used to calculate the concentrations of individual lipoprotein classes. The values correlated with those obtained using commercial kits for HDL and LDL cholesterol. The position of the LDL peak in the gradient and its shape varied between plasma samples and was indicative of the density of the predominant LDL class. The novel protocol offers a rapid, reproducible and accurate single-step centrifugation method for the determination of HDL, LDL, and VLDL cholesterol, and TG, and identification of LDL subclass pattern.

Centrifugation, Density Gradient↗
PubMed2000

Survival and growth of developing rats during centrifugation at 2G.

We studied the effects of 2G hypergravity on the survival, body mass and growth of postnatal rats (Rattus norvegicus). Nursing litters comprised of either neonatal (Postnatal day [P]7) or pre-weanling (P14) rats and their mothers were exposed to 16 days of continuous centrifugation. All of the offspring survived and gained body mass, indicating that mothers nursed their young. Following the onset of centrifugation, neonatal and pre-weanling rats showed a reduction in growth relative to age-matched environmental controls (EC). At the completion of testing, body mass of the hypergravity (HG) groups was significantly less than that of controls (p<0.05). Over the course of the test, the HG-exposed P7 group showed an overall 55% gain in body mass as compared to a 71% increase in controls, while the HG-exposed P14 group showed a 62% increase relative to 75% in controls. Neonatal offspring (P7) gained body mass during centrifugation, but at significantly slower rates as compared to EC controls (p<0.05). In contrast, growth rates of pre-weanling (P14) rats were not reduced relative to controls, possibly related to the initiation of weaning, around P18 in the rat. These findings raise key issues relevant to studies of nursing mammals reared in altered gravity.

Age Factors↗
PubMed2003

[Development of a measurement and control system of human centrifuge].

OBJECTIVE: To develop measurement and control system for human centrifuge to simulate arbitrary hypergravity curves. METHOD: The human centrifuge is controlled by the upper and lower level computers. The measurement and control computer is as upper, and the real-time controller as lower. RESULT: The system performance could satisfy the requirement of the human centrifuge. CONCLUSION: The measurement and control system can achieve a high control precision. It is safe, reliable and easy to operate.

Centrifugation↗
PubMed1992

Effect of centrifugation on amniotic fluid phospholipid composition.

The first step in the determination of phospholipid in amniotic fluid is generally the removal of cells and debris from the fluid by centrifugation. Low-speed centrifugation of the supernatant is reported to have the same phospholipidic profile and L/S, PG/S and PI/S ratios similar to those of the uncentrifuged amniotic fluid sample. With high-speed centrifugation almost all the pulmonary surfactant seems to be recovered in pellet with the same characteristics as the uncentrifuged amniotic fluid.

Amniotic Fluid↗
PubMed2003

Molecular detection of breast cancer cells in the peripheral blood of advanced-stage breast cancer patients using multimarker real-time reverse transcription-polymerase chain reaction and a novel porous barrier density gradient centrifugation technology.

PURPOSE: The goal of this study was to develop a molecular diagnostic assay to detect circulating breast cancer cells in the peripheral blood for the purpose of staging breast cancer. Our aim was to make available an assay that was not limited by the low concentration of circulating breast cancer cells and the background gene expression that is typically found in peripheral blood. EXPERIMENTAL DESIGN: In this study, we investigated the ability of two new technologies to significantly enhance the quantification of gene expression in the peripheral blood: enrichment by a novel porous barrier density gradient centrifugation technology; and multimarker real-time reverse transcription-PCR (RT-PCR). RESULTS: Using fluorescence-labeled breast cancer cells and flow cytometry, we show that processing peripheral blood by porous barrier density gradient centrifugation results in a 300-fold enrichment of breast cancer cells. Real-time RT-PCR analysis confirmed a concomitant reduction in background expression of the CK19 and MUC1 genes after enrichment. In a pilot study, porous barrier density gradient centrifugation and multimarker real-time RT-PCR enabled our laboratory to detect breast cancer-associated gene overexpression in 13 of 20 (65%) stage IV breast cancer patients. Nine of these 14 patients overexpressed three or more markers. CONCLUSIONS: These results confirm the promise of such a molecular diagnostic assay and suggest that additional studies are needed to precisely define the clinical relevance.

Biomarkers, Tumor↗
PubMed2004

Centrifuge training increases presyncopal orthostatic tolerance in ambulatory men.

INTRODUCTION: Exposure to spaceflight or simulations of microgravity reduce human postflight orthostatic tolerance. Exercise training and volume loading can reduce associated losses of plasma volume and muscle strength, but are not successful in maintaining postflight orthostatic tolerance. A preliminary study (16) indicated that short bouts of artificial gravity (AG) training on a centrifuge could increase orthostatic tolerance in healthy, ambulatory volunteers. We tested the same AG protocol for its tolerance effect on 14 men who underwent a 3-wk exposure to Gz acceleration training on NASA-Ames' (Moffet Field, CA) human-powered centrifuge. METHODS: Subjects trained supine (head near the center of rotation) and in pairs (one subject rode passively while the other provided power to operate the 1.9-m centrifuge). The acceleration profile consisted of 7 min at 1 Gz before alternating between 1 and 2.5 Gz at 2-min intervals for 28 min. Each subject's presyncopal orthostatic tolerance limit (to a combination of 70 degrees head-up tilt and increasing lower body negative pressure) was determined before and after training. RESULTS: There were no significant differences between training groups, but presyncopal orthostatic tolerance time was improved 17 +/- 10% (p < 0.05) for the combined groups. Mechanisms associated with increased tolerance included: increased cardiac output (p < 0.04), stroke volume (p < 0.01) and low-frequency spectral power of arterial pressure (p < 0.006), and decreased arterial pressure (p < 0.05) and vascular resistance (p < 0.04). Artificial gravity training in this group of men appears to increase orthostatic tolerance through a combination of decreased vascular resistance and enhanced cardiac function.

Adaptation, Physiological↗
PubMedDate not supplied

[The short-arm centrifuge: history and possible uses in cosmonautics and health care services].

The review has the objective to analyze applicability of short-radius centrifuges (SAC) in clinical practice. Attempts to treat with centrifuges were made already in the XVIIIth century by E. Darwin (1794) and then E. Horn (1818). Positive results were reported but without particulars of the therapeutic courses. Interest in this method was rekindled by initiation of investigations of the centrifuge as a means to counteract the negative effects of microgravity during manned flights to space. The all-round studies of SAC powers at the Institute for Biomedical Problems attested its efficiency in prevention and therapy of the human body deconditioning brought on by simulated microgravity (bed rest, water immersion), in the 80s the method was tested on patients affected with leg ischemi, and complicated reparation of bone fractures. Collaboration of IBMP investigators with clinical doctors (1987) and a series of dedicated investigations (2000) favoured the view that SAC can be successfully used to prevent and treat blood supply disturbances in legs.

Astronauts↗
PubMed2005

Centrifuge training program with "push-pull" elements.

INTRODUCTION: Pilots of fighter aircraft are often exposed to maneuvers that produce negative acceleration (-Gz) immediately followed by positive acceleration (+Gz). This sequence has been found to reduce tolerance to +Gz, a phenomenon known as the "push-pull" effect. We devised a centrifuge training program to demonstrate this phenomenon to pilots. METHODS: The centrifuge of the Military Institute of Aviation Medicine in Warsaw, Poland, was modified in 1996 to allow active positioning of the gondola during rotation. Head-down position of -6 degrees to -40 degrees were used to produce relative -Gz (r-Gz) in a range down to 0.2. As a side effect, this produces Gy acceleration between -1.3 Gy and -1.6 Gy. Pilots completed normal centrifuge training, including a relaxed, gradual-onset run and three rapid-onset runs. They were then exposed to a profile that included a series of push-pull exposures where r-Gz was followed by +Gz with stepwise increases in the latter from +2.5 to +5 Gz. The final profile was a simulated aerial combat maneuver with push-pull elements. RESULTS: The trainees expressed surprise at the push-pull effect, which forced them to begin an anti-G straining maneuver at lower levels than normal. They complained about the presence of the Gy, which rarely occurs in aircraft. DISCUSSION: This type of profile appears useful for training pilots about the push-pull phenomenon. After collection of additional data, the profiles may be refined.

Aerospace Medicine↗
PubMed2004

[Effects of centrifuge training on mRNA expression in different rat tissues].

OBJECTIVE: To demonstrate the tissue specific expression of five rat genes related to centrifuge training and the relationship between expression change and duration of training. METHOD: mRNA was extracted from hearts, brains, kidneys, lungs and intestines of rats after different durations of training. Five genes obtained by SSH from centrifuge-trained rats were labeled by Dig-11-dUTP as probes. The expression levels were measured by thin-line hybridization. Optical density (OD) values were obtained by scanning and treated with statistics. RESULT: As compared with control group, the new gene CH157 expression decreased in hearts and brains of rats trained for 6 d (P<0.05), but returned to control levels after 12 d training; the new gene CH244 expression depressed in rat hearts, brains, and intestines after 6 d or 12 d training, but it was not statistically significant owing to large individual differences; gene expression of protein inhibitor of neuronal nitric oxide syntheses (PIN) increased gradually and significantly in rat hearts (P<0.01 after 12 d training) and kidneys (P<0.05 after 12 d training); Cyt b gene expression in rat hearts and brains increased increasingly (P<0.01 after 12 d training), however, it increased obviously (P<0.05) in kidneys, lungs and intestines of rats trained for 6 d, while it returned back a little in rats trained for 12 d; enlongation factor 1-alpha expression levels in intestines of rats trained for 6 d increased significantly (P<0.05), but it became no significant in rats trained for 12 d, while the expression in brains increased gradually (P<0.01). CONCLUSION: It suggested that the change in gene expression in several tissues of rats caused by centrifuge training contribute in enhancing +Gz tolerance.

Acceleration↗
PubMed2004

Centrifuges and inertial shear forces.

Centrifuges are often used in biological studies for 1 x g control samples in space flight microgravity experiments as well as in ground based research. Using centrifugation as a tool to generate an Earth like acceleration introduces unwanted inertial shear forces to the sample. Depending on the centrifuge and the geometry of the experiment hardware used these shear forces may contribute as much as 99% to the total force acting on the cells or tissues. The inertial shear force artifact should be dealt with for future experiment hardware development for Shuttle and the International Space Station (ISS) as well as for the interpretation of previous spaceflight and on-ground research data.

Cell Adhesion↗
PubMed1992

Peroxidase activity loss after filtration and centrifugation of whole saliva. Influence of citrate.

Filtration or centrifugation are two methods frequently used to clarify human whole saliva. This study compares both the drop in peroxidase activity following filtration (49.3% +/- 16.4%; N = 12) or centrifugation (33.6% +/- 15.9%; N = 6) and the drop in total protein concentration after filtration (33.9% +/- 13.4%) and centrifugation (23.6% +/- 8.7%). After filtration, the loss was not only due to retention of the large particle-bound fraction but also to adsorption on the filter membranes. This adsorption could be inhibited by a previous dilution of saliva in a citrate buffer, which also gave rise to active subunits with a molecular weight less than or equal to 100 kDa.

Adsorption↗
PubMed2006

Centrifuge "therapy" for psychiatric patients in Germany in the early 1800s.

In 1818, Dr. Ernst Horn (1774-1848) reported miraculous cures for patients suffering from hysteria through the use of centrifuges at the psychiatric wards of the Charit6-Hospital in Berlin during the previous decade. In his book, "Public Account Concerning My 12 years' Service as Second Physician of the Royal Hospital in Berlin, Including Experiences from Hospitals and Mental Institutions," a full description of the indications and methods for treatment of mental illness, including technical data and construction costs for a rotating bed and rotating chair, is given. The rotating bed was turned by a crankshaft connected by ropes to a capstan. Slowing or stopping was achieved by tensing a rope around a wheel near the ceiling. With a diameter of 13 ft, this therapeutic instrument was capable of producing up to 4 to 5 -Gz in the head region. Several hundred patients and many volunteer subjects, including medical doctors, were reported to have been exposed to the rotating devices, along with some miraculous cures. Apart from the ethical problems associated with this type of torturous treatment, the rotating bed could be described as an ancient centrifuge. With the well-documented observations made on this device, the very first description of G-induced biomedical effects, such as shortness of breath and a feeling of oppression and anxiety, was given: These observations were comparable to those made one century later on human centrifuges and in flight.

Aerospace Medicine↗
PubMed2006

Roll-tilt perception during gondola centrifugation: influence of steady-state acceleration (G) level.

BACKGROUND: Spatial disorientation is an important problem in aviation. The significance of the C level for illusions elicited from the semicircular canals is not clear. The aim of the present investigation was to elucidate how a gravitoinertial force, acting in parallel with the subject's long (z) axis, may influence the magnitude and persistence of canal-induced tilts of the subjective visual horizontal (SVH) present after acceleration in a gondola centrifuge. METHODS: The SVH was measured by means of an adjustable luminous line in darkness. Two series of experiments were performed. In series 1, the SVH was measured in 13 subjects at 1.1 G, 1.7 G, and 2.5 G. In series 2, it was measured in 8 subjects at 2.5 G and 4.5 G. RESULTS: After acceleration of the centrifuge the SVH was tilted relative to the gravitoinertial horizontal. The direction of tilt was compensatory to the gondola inclination. In series 1 the initial SVH tilt was: 16.2 +/- 7.0 degrees (1.1 G), 24.2 +/- 10.2 degrees (1.7 G), and 27.1 +/- 13.9 degrees (2.5 G). In series 2 it was: 27.6 +/- 14.6 degrees (2.5 G), and 31.2 +/- 18.8 degrees (4.5 G). The gain for this response, defined as the ratio between the initial tilt and the inclination of the gondola, was: 0.65 +/- 0.28 (1.1 G), 0.45 +/- 0.19(1.7 G), 0.41 +/- 0.21 (2.5 G) (series 1); and 0.42 +/- 0.22 (2.5 G), and 0.40 +/- 0.24 (4.5 G) (series 2). Thus, an increase from 1.1 G to 1.7 G caused a reduction in the gain, but at G levels beyond 1.7 G there was no further decrease. The time constant for exponential decay tended to increase with the G level. It was: 61 +/- 31 s (1.1 G), 84 +/- 36 s (1.7 G), 89 +/- 42 s (2.5 G) (series 1); and 67 +/- 49 s (2.5 G), and 101 +/- 73 s (4.5 G) (series 2). CONCLUSION: It appears that otolithic stimulation via an increased gravitoinertial force vector, acting in parallel with the head and body long axis, does not substantially influence the magnitude of the canal-mediated sensation of roll-tilt after acceleration in a swing-out gondola centrifuge. Nor does it reduce the duration of this sensation.

Acceleration↗
PubMedDate not supplied

Influence of centrifugal blood pumps on the elasticity of erythrocytes.

The influence of centrifugal blood pumps on the elasticity of erythrocytes was tested in an in vitro set-up. Fresh bovine blood was pumped by vaneless and impeller blood pumps with low and high hemolytic potential (1L priming volume, flow 5 L/min versus 150 mmHg, pumping time 6 hours). The elasticity of the red blood cells was measured by laser diffraction. Starting with an elasticity of 238 +/- 39, the overall change during 6 hours was 12 +/- 38 compared to a change of the control value of -13 +/- -58. Even a pump with very high hemolytic potential (Hemolysis index 21.9) did not cause relevant changes of elasticity. It is concluded that 1) elasticity is not a useful parameter to use in the evaluation of centrifugal pumps, and 2) the mechanical trauma caused by centrifugal pumps produces no relevant permanent alteration of the elastic properties of red blood cells, at least under in-vitro conditions.

Animals↗
PubMed1991

Prevention of graft-versus-host disease by lymphocyte depletion of the bone marrow graft with use of counterflow centrifugation.

A combination of density flotation centrifugation and counterflow centrifugation (elutriation) allows the elimination of 98% of the T-lymphocytes, present in a marrow aspirate. This reduces substantially the occurrence of graft versus host disease (GvHD) after transplantation without loss of the repopulation capacity. A limitation of the traditional Beckman elutriator rotor is the relatively small size of the elutriation chamber, which makes five to six runs, of one hour each, necessary to process the whole bone marrow graft. We developed a new elutriator rotor, containing four disposable elutriator chamber (Dijkstra BV, Amsterdam, The Netherlands), which allows to complete the lymphocyte elimination from the bone marrow graft within 2 hours. Ninety-nine consecutive patients were transplanted with elutriated MLC-negative bone marrow grafts from histocompatible siblings. Indications for transplantation were: AML (n = 32), ALL (n = 34) and CML (n = 33). The grafts contained after counterflow centrifugation a mean of 12.1 (+/- 2.4)% of the nucleated cells, 1.9 (+/- 1.4)% of the T-lymphocytes, and 93.5 (+/- 59.4)% of the CFU-GM, originally present in the collected bone marrow. Immunoprophylaxis post grafting was given to 97 BMT recipients. Primary graft failure occurred in 5 of 95 evaluable patients (5%). The probability of acute GvHD greater than grade 1 at day 100 after BMT was 16%. The projected 3-year estimate of extensive chronic GvHD was 13%. The low incidence of GvHD was associated with a relatively low transplant related mortality in patients above the age of 40 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Centrifugal pump as right ventricular assist pump in the treatment of right ventricular failure following resection of left atrial myxoma].

A 31-year-old woman had a left atrial myxoma associated with severe pulmonary hypertension and respiratory failure because of incarceration of the tumor to the mitral valve. Emergency surgery was performed, but the patient could not be weaned from cardiopulmonary bypass because of right ventricular failure. A Biomedicus centrifugal pump was used as a right ventricular assist pump. The result was a successful termination of cardiopulmonary bypass. With the support of an intra-aortic balloon pump, the right ventricular assist pump was removed 38 hours after the operation, and the intra-aortic balloon pump was terminated 2 days later. The centrifugal pump is very useful at the majority of centers where the pneumatically activated bi-valved ventricular assist device is unavailable. The Biomedicus centrifugal pump can be easily applied for treatment of perioperative right ventricular failure and is very useful for short-term use without systemic anticoagulants.

Adult↗
PubMed1990

[Clinical experience of mechanical ventricular support with centrifugal pump for severe ventricular failure after open heart surgery].

Five adult patients (pts) with age 15-67 (mean 43) received mechanical circulatory support with centrifugal pump (Biomedicus, BP-80, Sarns centrifugal pump) for postcardiotomy profound shock. Three pts underwent left ventricular support (LVS) alone, and the other 2 required biventricular support (BVS). Duration of the LVS ranged from 33 to 240 hours (mean 126 hours) and the right ventricular support 92, 120 hrs. Pump flow rate was 1.1 to 2.5 (mean 1.9) L/min/m2. Sixteen pumps were used and the pump exchange was performed 9 times in five pts and an average perfusion time per pump was 57 hrs. Two of 3 pts with LVS alone survived and one died of multiorgan failure associated with right heart dysfunction. In two pts with BVS, one survived and the other died of persistent low cardiac output early after pump removal. As the complication during mechanical support, bleeding was seen in 3 pts and cerebral infarction in one. Although centrifugal pump has potential limitation in antithrombogenicity and durability, this device provides a simple and effective mechanical circulatory support.

Adolescent↗