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At least 1,153 records · Page 64Linked to original sources
PubMed2006

[Preparation of Shuxiong micropellets by centrifugal granulation technology].

OBJECTIVE: To prepare shuxiong micropellets. METHOD: Shuxiong micropellets were prepared by using a centrifugal granulator. The formulation composition and process factors were optimized investigated by adopting several indices such as size distribution, repose angle, bulk density and friability as indexes. RESULT: The optimal process parameters were as follows. The ratio of fine intermediate product and MCC was 3:1 (w/w), the adhesive agent was 3% HMPC solution, the rotating rate of plate was 200 r x min(-1), the blower rate was 15 x 20 L x min(-1), the rate of air flow was 15 L x min(-1), the spray air pressure was 0.5 MPa, the rotating of spray solution pump was 5-25 r x min(-1) and the rotating rate of powder feed machine was 5-25 r x min(-1). CONCLUSION: Under the optimal conditions, micropellets prepared by using centrifugal granulator hadpossessed prefect shape and surface characteristics and the yield of shuxiong pellets was 90.5%.

Carthamus tinctorius↗
PubMed2007

Space cycle: a human-powered centrifuge that can be used for hypergravity resistance training.

INTRODUCTION: This study represents the first step toward testing the hypothesis that hypergravity can be used as a unique resistance training modality for maintaining the health and function of skeletal muscle in microgravity. The primary objectives of this study were to use a human-powered short-arm centrifuge for the following: 1) to determine whether subjects could perform squats under hypergravity conditions without developing motion sickness or illusory motion; 2) to measure foot forces while performing squats under hypergravity conditions; and 3) to determine the mechanical power required to produce 1.5, 2.0, 2.5, and 3.0 Gz (head to foot) at the feet. METHODS: Subjects (22 males and 19 females) performed 10 squats each at 1.5, 2.0, 2.5, and 3.0 Gz on a human-powered short-arm centrifuge, the space cycle. Foot forces during each squat were monitored using insole force sensors, and normalized to foot forces measured at 1 Gz (relative foot forces). RESULTS: Illusory motion was minimized using a visual focal point, and did not affect the ability of subjects to perform squats. The mean standing relative foot forces at 3.0 Gz were 2.3 and 2.4 for the male and female subjects, respectively. The work rate required to power the space cycle was a linear function of Gz, and is well within the aerobic scope of untrained individuals. DISCUSSION: The findings of this study demonstrate that hypergravity can be used as an effective modality for loading skeletal muscle and that subjects can perform squat resistance exercise without developing motion sickness or illusory motion.

Adaptation, Physiological↗
PubMedDate not supplied

Cryptosporidium merozoite isolation and purification using differential centrifugation techniques.

Simple modifications to a recently published merozoite purification procedure (Bjorneby et al., J. Immunol. 145:298, 1990) increased yields 3- to 5-fold. Calves were infected with 2.5 x 10(8) Cryptosporidium parvum oocysts and sacrificed 65 h post-infection. The ilium and caecum were removed. The tissue was sieved through a large strainer (2 mm2) to produce a homogeneous suspension. Red blood cells were removed by differential centrifugation (600 g); merozoites remained in the supernatant. The merozoites were pelleted (2,100 g) and washed in modified Hank's balanced salt solution deficient in Mg+2 and Ca+2. Percoll purification (density 1.070 g/ml and centrifugation speed of 22,000 g for 30 min) yielded 8 x 10(8) merozoites. Nineteen monoclonal antibodies (MAb) detected by either an enzyme-linked immunosorbent assay or an immunofluorescence assay, have been generated against the merozoite stage. Gels of proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver-stained showed that sporozoites and merozoites have many common lower molecular weight proteins. Western blots of sporozoite and merozoite antigens reacted with anti-sporozoite MAb showed several cross-reacting antigens shared by these life-cycle stages.

Animals↗
PubMed1991

[Comparison of positivity between density gradient centrifugal method and whole blood method in lymphocyte surface marker analysis with flow-cytometry].

The lymphocyte surface marker analysis with flow-cytometry is usually performed using a density gradient centrifugal method or a whole blood method. We have compared these two methods using several monoclonal antibodies and have found the significant difference in positivity all monoclonal antibodies except TCR-1 (anti alpha/beta receptor on T-lymphocyte). We found the significantly higher positivity of Leu12 and HLA-DR as well as lower of the other monoclonal antibodies by using whole blood method than by density gradient centrifugal method. We conclude that it is necessary to make a distinct description of the method used in the surface marker analysis.

Adult↗
PubMed1990

A centrifugal pump for graft replacement of the descending thoracic or thoraco-abdominal aorta.

Between January 1987, and December 1988, 14 cases of descending thoracic or thoraco-abdominal aortic aneurysm underwent operation using a prosthetic graft replacement. In order to avoid hypoperfusion to distal organs and proximal hypertension during aortic cross-clamping, two different adjuncts were used and the effectiveness of those methods were compared according to the results of surgery. Seven patients were treated with a temporary shunt of heparin-bonded tube from the left axillary artery to left femoral artery, or else Dacron vascular prosthesis from right axillary artery to right femoral artery (Group I). In Group II (seven patients), left heart bypass was performed, using a centrifugal pump from the left atrium to the left femoral artery with minimal heparinization. In Group I, there were two hospital deaths, due to respiratory and hepatic failure respectively, and paraplegia has occurred in one case. In Group II, there was no death during a post-operative observation period of 5-15 months, and there was no case of paraplegia. We think that temporary left heart bypass with a centrifugal pump seems to be the most useful method today for graft replacement of the descending thoracic or thoraco-abdominal aorta.

Adult↗
PubMed1979

Distribution of cholesterol and apolipoprotein A-I and A-II in human high density lipoprotein subfractions separated by CsCl equilibrium gradient centrifugation: evidence for HDL subpopulations with differing A-I/A-II molar ratios.

The purpose of this experiment was to characterize the high density lipoproteins (HDL) as a function of hydrated density. HDL was subfractionated on the basis of hydrated density by CsCl density gradient centrifugation of whole serum or the d 1.063-1.25 g/ml HDL fraction isolated from three men and three women. Apolipoprotein A-I and A-II quantitation by radial immunodiffusion showed that the A-I/A-II ratio varied with the lipoprotein hydrated density. The A-I/A-II molar ratio of HDL lipoproteins banding between d 1.106 and 1.150 g/ml was nearly constant at 2.2 +/- 0.2. In the density range 1.151-1.25 g/ml the A-I/A-II ratio increased as the density increased. On the other hand, in the density range between 1.077 and 1.105 the A-I/A-II ratio increased as the density decreased, ranging from 2.8 +/- 0.5 for the d 1.093-1.105 g/ml fraction to 5.6 +/- 1.3 for the d 1.077-1.082 g/ml fraction. The d 1.063-1.076 g/ml fraction and the d 1.077-1.082 g/ml fractions had comparable A-I/A-II ratios. Serum and the d 1.063-1.25 g/ml HDL fraction exhibited similar trends. The cholesterol/(A-I + A-II) ratio decreased as the density increased in all 12 samples (six serum and six HDL) examined. Gradient gel electrophoresis of the density gradient fractions showed that as the density increased from 1.063 to 1.200 g/ml the apparent molecular weight decreased from 3.9 x 10(5) to 1.1 x 10(5). HDL subfractions with the same hydrated densities had comparable molecular weights and A-I/A-II and cholesterol/(A-I + A-II) ratios when isolated from men or women. HDL contains subpopulations that differ in the A-I/A-II molar ratio.-Cheung, M. C., and J. J. Albers. Distribution of cholesterol and apolipoprotein A-I and A-II in human high density lipoprotein subfractions separated by CsCl equilibrium gradient centrifugation: evidence for HDL subpopulations with differing A-I/A-II molar ratios.

Apolipoproteins↗
PubMed1990

[Comparison of the therapeutic effectiveness of membrane and centrifugation plasmapheresis].

The authors compared 10 pairs of membrane plasmaphereses on an apparatus A 2008 PF and filter Plasmaflux P 2 with 10 centrifugation plasmaphereses on an apparatus Fenwal CS 3000. They evaluated the effectiveness by changes of plasma concentrations of total protein, albumin, beta 2 microglobulin, IgG, IgA, C3 complement, IgM, circulating immune complexes, urea, creatinine, uric acid, cholesterol, triacylglycerols and the clearance of these substances. Changes of plasma concentrations caused by plasmapheresis with the methods used did not differ in any of the investigated substances. The clearance of membrane plasmapheresis was for all substances higher than when the centrifugation method was used. Among values from which the clearance is determined no difference was proved between the two methods in the volume of exchanged plasma, the concentration of the substance in the removed plasma and its mid plasma concentration during the operation. The higher clearance of membrane plasmapheresis was due to the more rapid plasma exchange.

Centrifugation↗
PubMed1990

[1989 clinical experience with biomedicus centrifugal pump in the operation of the thoracoabdominal and thoracic aneurysm--assessment from the point of renal function].

It is generally accepted that operative procedures of thoracic aneurysm requires the use of some type of temporary vascular bypass when cross clamp is necessary. Past 10 years, we have used three types of temporary bypass. From 1979 to 1989, 78 patients with thoracic aneurysm were treated. In these patients, 25 patients with descending thoracic and thoracoabdominal aneurysm were divided into three groups on the basis of the type of bypass and evaluated from the point of postoperative renal function. Temporary vascular bypass using artificial graft was applied to 9 patients. Gott's shunt tube in stead of graft was used in 5 patients. Left ventricular bypass with Bio-Medics centrifugal pump was used in 11 patient. Among three groups, differences in age, diameter of the aneurysm, preoperative renal function and aortic clamp time were statistically not significant. Mean arterial pressure gradient between upper and lower extremities were 42 +/- 14 mm Hg in artificial graft group, 31 +/- 7 mm Hg in Gott group and 9 +/- 10 mm Hg in Bio-Pump group. Urine volumes during temporary bypass were 98 +/- 43 ml in artificial graft group, 120 +/- 54 ml in Gott group, 255 +/- 269 ml in Bio-Pump group. Left ventricular bypass with Bio-Medics centrifugal pump is an extremely useful method to protect renal function in thoracic aneurysm surgery.

Aged↗
PubMed1990

[A case of right ventricular failure after CABG successfully supported by right heart bypass with a centrifugal pump].

A 67-year-old woman underwent CABG because of severe triple vessel disease. She could not wean from CPB in spite of full inotropic drugs and IABP support due to right ventricular failure probably caused by the perioperative right ventricular infarction. Right heart bypass (RHB) with a centrifugal pump was used. Finally she could wean from CPB and took an uneventful postoperative course except mediastinitis. During 5 days of RHB operation ACT was maintained between 180s and 200s by systemic heparinization. RHB with a centrifugal pump is a reliable method to assist a failing right ventricle.

Aged↗
PubMed1990

Enhancing aircrew centrifuge high-G training using on-line videotape documentation.

Many air forces are training fighter aircrew to improve their tolerance to the high-G environment by using human centrifuges. It is important to enhance and upgrade the methods and techniques employed in this aircrew training. At the Naval Air Development Center (NADC) we have developed several techniques to consolidate as much of the information as possible on the videotape recording of the centrifuge training. This includes a continuous electrocardiographic display, anti-G suit pressure tracing, heart rate parameters, +Gz parameter, and, if +Gz. induced loss of consciousness (G-LOC) occurs, the duration of incapacitation resulting from G-LOC. The techniques and information provided have been well received by Navy and Marine aviators participating in high-G training at NADC.

Aviation↗
PubMed1990

Allogeneic bone marrow transplantation for leukemia with marrow grafts depleted of lymphocytes by counterflow centrifugation.

Eighty consecutive patients were transplanted with human leukocyte antigen (HLA)-identical sibling marrow for acute myelogenous leukemia (AML, N = 29), acute lymphoid leukemia (ALL, N = 23), or chronic myelogenous leukemia (CML, N = 28). Donor marrow was depleted of lymphocytes using counterflow centrifugation. Median age of the recipients was 31 years. Pretransplant conditioning consisted of cyclophosphamide and fractionated total body irradiation (TBI) with a low (4.1 +/- 0.3 cGy/min) or high (13.1 +/- 1.6 cGy/min) midline average dose rate. In 43 patients, cytosine-arabinoside or anthracyclines were added to the conditioning regimen. Immunoprophylaxis posttransplant consisted of methotrexate (MTX) alone, cyclosporine A (CsA) in combination with MTX, or CsA alone; two patients received no immunoprophylaxis at all. Graft failure occurred in 4 of 77 evaluable patients (5%). The probability of acute graft-versus-host disease (GVHD) greater than or equal to grade 2 at day 100 after transplantation was 15%. The projected 3-year estimate of extensive chronic GVHD was 12%. Only three patients died of cytomegalovirus-interstitial pneumonitis. The projected 3-year probability of relapse was 30% (95% confidence interval [CI], range 8% to 53%) in transplants for AML in first complete remission (CR1), 35% (95% CI, 1% to 69%) after transplantation for ALL in CR1, and 38% (95% CI, 2% to 74%) after transplantation for CML in first chronic phase (CP1). The projected 3-year probability of leukemia-free survival (LFS) was 56% (95% CI, 35% to 77%) after transplantation for AML-CR1, 42% (95% CI, 16% to 69%) in patients transplanted for ALL-CR1, and 49% (95% CI, 18% to 80%) after transplantation for CML-CP1. After transplantation for AML-CR1, ALL-CR1, or CML-CP1, the median follow-up time for leukemia-free survivors was 31+, 30+, and 21+ months, respectively. Probabilities of relapse, survival, and LFS in AML-CR1 and ALL-CR1 transplants were comparable with those reported in recipients of untreated grafts. In patients transplanted for CML-CP1, probability of relapse was higher and probability of LFS was lower than in recipients of untreated grafts. In transplants for leukemia in CR1 and CP1, preparative regimen and immunoprophylaxis posttransplant were not associated significantly with the probability of acute GVHD greater than or equal to grade 2, extensive chronic GVHD, relapse, survival, or LFS. In bone marrow transplantation for leukemia, counterflow centrifugation is a useful technique for the prevention of GVHD.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1990

Recognizing +Gz-induced loss of consciousness and subject recovery from unconsciousness on a human centrifuge.

Human exposure to +Gz-induced loss of consciousness (G-LOC) remains of some concern relative to the well-being of the individuals experiencing the unconscious episodes. Detailed kinetic analysis of over 500 G-LOC episodes on a human centrifuge allowed an evaluation of the time for subjective recognition by observers of the onset of G-LOC and subsequent recovery to normal baseline conditions. The characteristics of early, coincident, and late recognition of the onset of G-LOC were evaluated. Earlier recognition of G-LOC was observed to occur when the rate of onset of the +Gz-stress was gradual (less than 0.6 G/s). Rapid onset rate (greater than 0.6 G/s) exposures were more likely to result in late recognition of G-LOC. The duration of the resulting period of unconsciousness (absolute incapacitation) was very sensitive to the time for recognition of G-LOC and most rapid return to a normal (+1 Gz) environment. The absolute incapacitation increased significantly from early (10.7 s) to coincident (11.4 s) to late (13.2 s) recognition of G-LOC which differed by a total of only 4.6 s. The results allow development of an initial standard of care envelope for apparently safe exposure of human subjects to centrifuge G-LOC since no adverse effects were observed with any of the exposures. The results also demonstrate the extreme sensitivity of the central nervous system to small changes in exposure to +Gz-stress which can be accurately measured.

Acceleration↗
PubMed1990

Separation of equine bronchopulmonary lavage cells by density gradient centrifugation and expression of procoagulant activity in unpurified cells and cell subpopulations.

Bronchopulmonary lavage was performed in 10 healthy horses and in 39 horses with chronic pulmonary disease. The predominant cell types were macrophages in healthy horses and neutrophils in severely diseased horses. Procoagulant activity (PCA) was detected in all 32 cell-free supernatants examined and in all 49 unpurified cell suspensions. Cells were separated by centrifugation on discontinuous gradients prepared either with Percoll or with Metrizamide. Macrophages were enriched in subpopulations of low density. Neutrophils could not be purified by density gradient centrifugation using either gradient medium. PCAs of cell subpopulations were plotted against their respective macrophage, neutrophil, and lymphocyte content. PCA was positively correlated with macrophage content (P less than 0.001) and negatively correlated with neutrophil (P less than 0.02) and lymphocyte (P less than 0.001) content. Therefore, PCA of equine lung cells most likely originates from macrophages as shown in other species. The density shift of lung neutrophils requires further investigation.

Animals↗
PubMed1975

Specific partial depletion of graft-vs-host activity by incubation and centrifugation of mouse spleen cells on allogeneic spleen cell monolayers.

Spleen cells (from BALB/c mice immunized with the C57BL/6 lymphoma EL4, or from non-immune BALB/c) were incubated on monolayers of [C57BL/6 times BALB/cF1 (B6CF1) spleen cells on polylysine-coated polystyrene Petri plate, for 1/2 hr or for 1 hr at 37 degrees C followed by centrifugation of the monolayers for 5 min at 70 times G to 110 times G at 34 to 37 degrees C. Control monolayers were BALB/c spleen cells. As measured by the Simonsen spleen weight assay in neonatal mice, graft-vs-host (GVH) activity was partially depleted in cell populations nonadherent to B6CF1 monolayers. Residual GVH activity of these nonadherent cells was about half that of cells incubated on the control syngeneic monolayers (the mean of eight experiments was 49% +/- 11% S.D.). Two or three consecutive cycles of incubation and centrifugation did not significantly diminish the residual GVH activity, suggesting that spleen cells with GVH activity are heterogeneous with respect to binding to allogeneic target cells under the above conditions. Cell populations nonadherent to third-part [A times AL]F1 monolayers retained full activity, and cell populations partially depleted of GVH activity in B6CF1 neonates had full activity in third-party [BALB/c times AL]F1 neonates.

Animals↗
PubMedDate not supplied

[Nature of the heterogeneity of 30S ribosomal subparticles in vitro. I. Effect of large centrifugal fields during 30S subparticle isolation on their capacity for codon-dependent tRNA binding].

Measurements of association constants (Ka) of specific [14C]Phe-tRNAPhe with a 30S..poly(U) complex revealed that values of these constants vary from 0.5.10(7) up to 1.5.10(8) M--1 when different 30S subunit preparations were used at the same medium conditions (20 mM Mg2+, 200 mM NH4, 0 degrees C). Analysis of these data showed that the higher the rotor speeds were used during separation of 70S ribosomes into subunits, the less Ka values were measured. In special experiments on sedimentation of pure 30S subunits at different rotor speeds it was found that the decrease of Ka values was caused due to the additional reversible dissocation of ribosomal proteins from 30S subunits at high (the order of 100 000.g) centrifugal fields. As a possible mechanism of such dissociation we suggest the influence of high hydrostatic pressure on the association constants of S-proteins with 30S subunits. Data presented in this paper demonstrate that at least one of the reasons for the physical and functional heterogeneity of 30S subunits in vitro derives from the application of high centrifugal fields during isolation of ribosomal subunits.

Cell Fractionation↗
PubMed1989

Subcellular fractionation of epithelial cells from toad urinary bladder. 1. Assay of marker enzymes and differential centrifugation.

We have undertaken the analytical fractionation of epithelial cells from toad urinary bladder, a tissue extensively used to study epithelial transport of ions and water. In an attempt to establish markers for the main subcellular organelles, a number of enzymes were assayed in cell homogenates. The nearly ubiquitous plasma membrane marker 5'-nucleotidase, and the transferases that donate N-acetylglucosaminyl, galactosyl, and sialyl residues to glycoproteins and glycolipids in the Golgi complex were not detectable. Glucose-6-phosphatase activity was low in relation to that of nonspecific phosphatases and, therefore, not suitable for identifying the endoplasmic reticulum. Like the cytosolic enzyme lactate, dehydrogenase, catalase was essentially found in the high-speed supernatant, with a noteworthy part of aminopeptidase (substrate, leucyl-beta-naphthylamide) and NAD glycohydrolase. Other enzymes, including cytochrome c oxidase, acid phosphatase, acid N-acetyl-beta-glucosaminidase, alkaline phosphatase, alkaline phosphodiesterase I, nucleoside diphosphatase (substrate ADP), oligomycin-resistant Mg++-ATPase, and mannosyltransferase (acceptor, dolichylphosphate) were fairly active and largely sedimentable. After differential centrifugation, cytochrome oxidase, acid phosphatase, and acid N-acetyl-beta-glucosaminidase were typically associated with the large granule fraction, whereas the other sedimentable enzymes exhibited a broad distribution profile overlapping the nuclear, large granule, and microsome fractions. Their behavior in density equilibrium centrifugation is examined in a companion paper.

Animals↗
PubMed1989

[Use of the centrifugation-culture technique for the rapid diagnosis of cytomegalovirus].

Cell culture is the reference method for the detection of cytomegalovirus (CMV) in clinical samples. However, owing to the slow development of cytopathic effect (CPE), the cultures should be observed for at least four weeks before being discarded as negative. We have used a monoclonal antibody for the immunofluorescent detection of the early CMV antigen 48 hours after the inoculation of the samples, by means of centrifugation on embryonic human lung fibroblasts. Fifty-nine out of the 566 investigated urine samples were positive for early antigen in culture and 57 in conventional culture on the same cellular type (mean time of development of CPE 11.8 days). A modification facilitating sample processing and a considerable saving of reactive is described. The technique for the detection of early CMV antigen in culture after centrifugation can be used for the diagnosis of CMV infection owing to its high sensitivity and the rapidity of the results.

Adult↗
PubMed1989

Enhancement of in vitro infectivity of simian malaria sporozoites to hepatocytes by centrifugation.

Sporozoites of Plasmodium cynomolgi, Plasmodium knowlesi, and Plasmodium coatneyi were deposited onto monolayers of hepatocytes from rhesus monkeys (Macaca mulatta). When sporozoites were centrifuged (1,600 g for 5 min), 4-13-fold more schizonts were observed than were found in noncentrifuged control cultures. Centrifugation of hepatocyte monolayers before adding sporozoites did not modify the number of parasites.

Animals↗