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At least 1,261 records · Page 70Linked to original sources
PubMed1993

Pharmacological studies of centrifugation-induced analgesia.

Subjecting rats to a brief period of centrifugal rotation produces a brief analgesia (1-2 min) that is similar to that produced by pretreatment with morphine. The effect of the morphine is blocked by naloxone, while that of the centrifugal rotation is only partially blocked by the same dose of naloxone. Cholinergic blocking agents such as scopolamine are also capable of partially blocking the rotational-induced analgesia. The combination of pretreatment with scopolamine plus naloxone is capable of completely blocking the rotational-induced analgesia, suggesting the involvement of both central cholinergic and endogenous opioid components.

Analgesia↗
PubMed1990

The efficiency of production, centrifugation, microinjection and transfer of one- and two-cell bovine ova in a gene transfer program.

Forty crossbred beef heifers were superovulated with 2000 IU pregnant mare serum gonadotropin (PMSG) and mated twice by natural service during estrus. Ovulations were counted and ova were recovered during mid-ventral laparotomy between 44 and 54 h after the onset of estrus. The overall donor ovulation rate (M+/-SEM) was 15.2+/-1.3. There was a positive association between ovulation rate and the number of ova recovered (P<0.001), and between ovulation rate and the incidence of ova advanced beyond the two-cell stage of development (P<0.05). When grouped on the basis of superovulation response, the numbers (M+/-SEM) of recovered one-cell, two-cell and more advanced ova were 3.7+/-0.7, 1.0+/-0.3 and 0.5+/-0.3, respectively, for donors with up to 15 ovulations. The corresponding numbers for donors with more than 15 ovulations were 7.2+/-1.8, 6.0+/-1.3 and 2.8+/-1.2, respectively. Following centrifugation, pronuclei were visible in 68% of one-cell ova, and nuclei were visible in 80% of two-cell ova. Approximately 20% of ova were destroyed during DNA microinjection. A total of 66 centrifuged and DNA-injected ova were transferred to the oviducts of 26 crossbred beef heifers, each receiving two, three or four ova. Echography at Day 55 confirmed that 14 (54%) heifers were pregnant with 26 (39%) fetuses. Eleven heifers were held to calve and produced 21 calves.

Journal Article↗
PubMed1981

Centrifugal assessment of cell adhesion.

The design of a chamber for determining the centrifugal force necessary to detach cells from various substrates is presented. Cells from an SV40-transformed murine peritoneal macrophage line and human erythrocytes were used to assess the feasibility of using the chamber for studies of cell adhesion. This work was confirmed the usefulness of the chamber and provided data concerning the force necessary to detach the cells. These data indicated that the percentage of cells detached from a glass substrate was not a function of force alone. The number of cells detaching increased with the impulse applied to the cells when they were exposed to a constant force. Similarly, when the impulse applied to the IC21 cells was maintained at a constant level, the percentage of cells detached by a centrifugal force increased with the magnitude of the force.

Animals↗
PubMed1992

Comparison of MRC-5 and continuous cell lines for detection of cytomegalovirus in centrifugation cultures.

Continuous cell lines were assessed for use for rapid human cytomegalovirus (HCMV) detection procedures combining tissue culture, centrifugation, and immediate early antigen (IEA) immunostaining. Human cells (MRC-5 embryonic fibroblasts, U-373MG astrocytoma cells, differentiated teratocarcinoma (Tera-2) cells), murine cells (BALB/c-3T3 and Y-1 cells), BHK21 hamster cells, and mink lung (ML) cells were first inoculated with HCMV laboratory strain. IEA synthesizing cells were detected by immunoperoxidase assay using a monoclonal antibody. ML cells and differentiated Tera-2 cells exhibited more positive cells than MRC-5 cells. BHK21, and MRC-5 cells were equivalent in sensitivity whereas U-373MG, BALB/c-3T3, and Y-1 cells had only reduced IEA positive cells. When 63 urine specimens were inoculated onto MRC-5, ML and differentiated Tera-2 cells, 20 (31.7%) were positive in MRC-5 cells versus 18 (28.5%) in ML or Tera-2 cells. Moreover, greater numbers of infected cells were detected in MRC-5 cells than in these two cell lines. MRC-5 cells were superior for detection of HCMV in clinical samples by centrifugation cultures.

Animals↗
PubMed1994

Is nitric oxide a transmitter of the centrifugal projection to the avian retina?

The chicken retina contains a population of prominent elements in the inner nuclear layer, which stain for NADPH-diaphorase. In distribution and morphology, these elements resemble the terminals of the centrifugal projection from the isthmo-optic nucleus. This identification was confirmed by showing that the NADPH-diaphorase-positive elements in the retina degenerated after destruction of the isthmo-optic nucleus or tract. These results indicate that the centrifugal projection to the retina in birds uses nitric oxide as a messenger or transmitter, in addition to a more conventional but as yet unidentified transmitter.

Animals↗
PubMed1985

Removal of large lipid droplets from cytochalasin B-treated chondrocytes by high speed centrifugation.

Chondrocytes isolated from auricular cartilage of 10-week-old rabbits were exposed to cytochalasin B and centrifuged in Percoll solution at 50.000 g for 1 h. This treatment removed the large fat droplets present in the majority of chondrocytes without impairing their viability. It appears that after destruction of actin filaments by cytochalasin, large fat droplets are extruded from the cells during high speed centrifugation due to the difference in the specific weight of fat and chondrocyte cytoplasm. Conceivably, on the same principle other materials could also be eliminated from the cells.

Animals↗
PubMed1988

Detection of cytomegalovirus in clinical specimens using shell vial centrifugation and conventional cell culture.

Shell vial centrifugation and conventional cell culture methods for detecting cytomegalovirus (CMV) were compared in clinical specimens. Our data confirm that the shell vial centrifugation method is more sensitive and rapid than conventional cell culture; however, due to the shell vial method's problems with toxicity to the fibroblast monolayer, both methods must be performed if all specimens positive for CMV are to be detected.

Cytomegalovirus↗
PubMed2004

A closed perfusion system with heparin coating and centrifugal pump improves cardiopulmonary bypass biocompatibility in elderly patients.

BACKGROUND: Cardiopulmonary bypass induces a systemic inflammatory and hemostatic activation, which may contribute to postoperative complications. Our aim was to compare the inflammatory response, coagulation, and fibrinolytic activation between two different perfusion systems: one theoretically more biocompatible with a closed-circuit, complete heparin coating, and a centrifugal pump, and one conventional system with uncoated circuit, roller pump, and a hard-shell venous reservoir. METHODS: Forty-one elderly patients (mean age, 73 +/- 1 years, 66% men) undergoing coronary artery bypass grafting or aortic valve replacement were included in a prospective, randomized study. Plasma concentrations of complement factors (C3a, C4d, Bb, and sC5b-9), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-8), granulocyte degradation products (polymorphonuclear elastase), and markers of coagulation (thrombin-antithrombin) and fibrinolysis (D-dimer, tissue plasminogen activator antigen and tissue plasminogen activator-plasminogen activator inhibitor-1 complex) were measured preoperatively, at bypass during rewarming (35 degrees C), 60 minutes after bypass, and on day 1 after surgery. RESULTS: The mean concentrations of C3a (-39%; p = 0.008), Bb (-38%; p < 0.001), sC5b-9 (-70%; p < 0.001), interleukin-8 (-60%; p = 0.009), polymorphonuclear-elastase (-55%; p < 0.003), and tissue plasminogen activator antigen (-51%; p = 0.012) were all significantly lower in the biocompatible group during rewarming. Sixty minutes after bypass, the mean concentrations of sC5b-9 (-39%; p = 0.006) and polymorphonuclear-elastase (-55%; p < 0.001) were lower in the biocompatible group. CONCLUSIONS: The results suggest that a closed perfusion system with a heparin-coated circuit and a centrifugal pump may improve cardiopulmonary bypass biocompatibility in elderly cardiac surgery patients in comparison with a conventional system.

Aged↗
PubMed2005

GnRH-immunoreactive centrifugal visual fibers in the Nile crocodile (Crocodylus niloticus).

Thin varicose centrifugal visual fibers, between 30-45 in number and displaying cGnRH-I immunoreactivity, were identified in Crocodylus niloticus. Approximately 80% of these fibers were also FMRF-amide-like immunoreactive. The cGnRH-I fibers extended from the preoptic region to the retina where they appeared to terminate in the external portion of the inner plexiform layer. The location of their neurons of origin could not be determined precisely following the intraocular injection of the retrograde axonal tracer RITC. Nevertheless, the presence of cGnRH-I-immunoreactive neurons exclusively within the complex comprising the terminal nerve and the septo-preoptic region, and of several retinopetal fibers labelled retrogradely with the axonal tracer at the septo-preoptic junction, indicates that the cGnRH-immunoreactive centrifugal visual system originates from within this complex.

Alligators and Crocodiles↗
PubMed2005

Partial support with a centrifugal left ventricular assist device reduces myocardial oxygen consumption in chronic, ischemic heart failure.

BACKGROUND: Left ventricular assist devices (LVAD) are increasingly used for heart failure (CHF); however, the level of optimal support has not been elucidated. We hypothesize that partial LVAD support in an ovine model of microinfarction-induced CHF significantly reduces left ventricular myocardial oxygen consumption (LVVO2). METHODS AND RESULTS: Microembolization of the circumflex coronary artery was used to induce CHF in 5 sheep (ejection fraction 28 +/- 2%). Four months later, animals underwent implantation of a centrifugal LVAD. LVAD flow was incrementally increased from 0% (baseline) to 25%, 50%, and 75% support of the LV. LVVO2 and stroke work (SW) were calculated at each increment. At baseline, LVVO2 (microL/100 g LV/beat) measured 43.2 +/- 3.4. LVVO2 decreased to 26.5 +/- 8.2,* 20.3 +/- 8.9,* and 12.6 +/- 6.3* at 25%, 50%, and 75% support (*P < .05). SW (mm Hg/mL) measured 1933.0 +/- 275.7 at baseline and decreased to 1588.0 +/- 204.1, 1181.0 +/- 157.2,* and 764.5 +/- 171.7* at 25%, 50%, and 75% support. Cardiac output, heart rate, and left main coronary artery blood flow were unaffected with partial support. CONCLUSION: Complete support with a centrifugal LVAD is not necessary for achieving significant reductions in LVVO2 . Partial support of as little as 25% significantly reduces LVVO2 in CHF through comparatively minor reductions in cardiac work. This is the first study to examine partial LVAD support in a CHF model.

Animals↗
PubMed2004

Preparative isolation and purification of celastrol from Celastrus orbiculatus Thunb. by a new counter-current chromatography method with an upright coil planet centrifuge.

A new counter-current chromatography (CCC) method with an upright coil planet centrifuge, which holds four identical multilayer coil columns in the symmetrical positions around the centrifuge axis, was applied to the isolation and purification of celastrol from the roots of Celastrus orbiculatus Thunb. The crude celastrol was obtained by elution with light petroleum from ethanol extracts using 15 cm x 5 cm i.d. silica gel flash chromatography. Preparative CCC with a two-phase system composed of light petroleum (bp 60-90 degrees C)-ethyl acetate-tetrachloromethane-methanol-water (1:1:8:6:1, v/v) was successfully performed, yielding 798 mg celastrol at 99.5% purity from 1020 mg of the crude sample in one step separation.

Celastrus↗
PubMed2005

Learning-induced modulation of oscillatory activities in the mammalian olfactory system: the role of the centrifugal fibres.

In the mammalian olfactory system, oscillations related to odour representation have been described in field potential activities. Previous results showed that in olfactory bulb (OB) of awake rats engaged in an olfactory learning, odour presentation produced a decrease of oscillations in gamma frequency range (60-90 Hz) associated with a power increase in beta frequency range (15-40 Hz). This response pattern was strongly amplified in trained animals. The aim of this work was twofold: whether learning also induces similar changes in OB target structures and whether such OB response depends on its centrifugal inputs. Local field potentials (LFPs) were recorded through chronically implanted electrodes in the OB, piriform and enthorhinal cortices of freely moving rats performing an olfactory discrimination. Oscillatory activities characteristics (amplitude, frequency and time-course) were extracted in beta and gamma range by a wavelet analysis. First, we found that odour induced beta oscillatory activity was present not only in the OB, but also in the other olfactory structures. In each recording site, characteristics of the beta oscillatory responses were dependent of odour, structure and learning level. Unilateral section of the olfactory peduncle was made before training, and LFPs were symmetrically recorded in the two bulbs all along the acquisition of the learning task. Data showed that deprivation of centrifugal feedback led to an increase of spontaneous gamma activity. Moreover, under this condition olfactory learning was no longer associated with the typical large beta band. As a whole, learning modulation of the beta oscillatory response in olfactory structures may reflect activity of a distributed functional network involved in odour representation.

Action Potentials↗
PubMed1999

Acute and temporary ventricular support with BioMedicus centrifugal pump.

BACKGROUND: Short-term ventricular and pulmonary support can be provided by the Medtronic BioMedicus (Eden Prairie, MN) centrifugal pump, which is available in most cardiovascular surgery centers. This versatile pump can provide support during cardiopulmonary resuscitation, cardiopulmonary bypass, extracorporeal membrane oxygenation, and ventricular assistance. A common use of the pump is to provide ventricular assistance for patients after cardiotomy or cardiogenic shock. METHODS: From January 1986 to September 1995, 141 patients at The Methodist Hospital in Houston, Texas were placed on the BioMedicus centrifugal pump after postcardiotomy cardiac failure. Patient treatment and postimplant complications are discussed. RESULTS: Fifty-four percent of the patients were weaned; however, only 22% survived to discharge. There was a very high mortality rate in the early stage after support was discontinued, after weaning, and after device removal. CONCLUSIONS: A high incidence of complications and death is likely related to the period of attempted weaning from cardiopulmonary bypass before the initiation of ventricular support. When weaning a patient from the pump during cardiopulmonary bypass or during ventricular assistance, it is important to optimize preload, after-load, ventricular function, and cardiac rhythm. In patients who have had postcardiotomy support, avoiding fluid overload, low colloid oncotic pressure, hypoperfusion, and use of excessive inotropic and vasoactive medications improve results.

Adolescent↗
PubMed2000

Quantitative immunogold evidence that glutamate is a neurotransmitter in afferent synaptic terminals within the isthmo-optic nucleus of the pigeon centrifugal visual system.

A quantitative electron microscopic analysis of glutamate (GLU) immunoreactivity using the post-embedding immunogold technique was carried out within the isthmo-optic nucleus (ION) of the pigeon centrifugal visual system (CVS). Measurements were performed in each of eight different categories of axon terminals, including those that were GABA-immunoreactive (-ir), considered representing control profiles and identified using a single or double-label immunocytochemical procedure. The results demonstrated that the glutamate immunogold particle densities for both mitochondrial and vesicular pools and for total surface area of bouton profiles were significantly higher in P1a, P1b and P2b terminals and not significantly different in P4 and P5 terminals compared to those recorded in control GABA-ir terminals (P2a, P2c, P3). Moreover, the values measured in GLU-ir positive profiles were all significantly higher than in either P4 or P5 terminals. The results suggest that tectal neurons, which provide the main input to the ION cells, are either inhibitory GABA-ir possibly associated with P2c and/or P3 terminals or excitatory GLU-ir via P1a, P1b and P2b terminals. Such differential effects of tectal afferents may be the basis for the modulation of centrifugal activity and consequently of end target retinal ganglion cell responses. The data are relevant to hypotheses implicating the avian CVS in mechanisms of selective enhancement of visual attention to either novel or meaningful stimuli within the visual field.

Animals↗
PubMed2002

Serotonergic innervation of the isthmo-optic nucleus of the pigeon centrifugal visual system. An immunocytochemical electron microscopic study.

The ultrastructural features of serotonergic fibers, terminals and synaptic contacts were studied with the pre-embedding immunocytochemical method in the isthmo-optic nucleus of the pigeon centrifugal visual system. The 5-HT immunoreactive (-ir) profiles were diffusely distributed and their density was low. The labeled axons were thin and unmyelinated (mean diameter=0.21+/-0.03 microm) though a few larger myelinated axons were observed (mean diameter=0.51+/-0.07 microm). The 5-HT-ir terminals or varicosities were small (diameter=0.71+/-0.54 microm) and contained small agranular synaptic vesicles (diameter=28.5+/-6.9 nm) and large granular vesicles (diameter=102.2+/-19.5 nm). The latter only constituted approximately 1% of the total profiles containing synaptic vesicles in the isthmo-optic nucleus. In single thin sections, only 5% of the 5-HT-ir varicosities exhibited an active asymmetrical zone synapsing upon dendritic profiles of centrifugal visual neurons. Calculations indicated that 17% of these 5-HT-ir varicosities were actually engaged in junctional synaptic relationships, whereas the remaining (83%) were nonjunctional. The data suggest that, within the isthmo-optic nucleus, 5-HT acts both at synaptic junctions (wiring transmission) and at a distance via the extracellular space (volume transmission). These 5-HT afferents could thus modulate the activity of the retinopetal neurons and visual information processing.

Animals↗
PubMed1988

Multi-stage mixer-settler planet centrifuge. Preliminary studies on partition of macromolecules with organic-aqueous and aqueous-aqueous two-phase solvent systems.

A rotary-seal-free planetary centrifuge holds a separation column which consists of multiple partition units (ca. 200) connected in series with transfer tubes. In the cavity of each partition unit the transfer tube extends to form a mixer which vibrates to stir the contents under an oscillating force field generated by the planetary motion of the centrifuge. Consequently, solutes locally introduced at the inlet of the column are subjected to an efficient partition process in each partition unit and separated according to their partition coefficients. The mixer tube equipped with a flexible silicone rubber joint was found to produce excellent results for partition with viscous polymer phase systems. The capability of the method was demonstrated on separation of cytochrome c and lysozyme using a PEG-aqueous dibasic potassium phosphate-aqueous two-phase solvent system.

Animals↗
PubMed1999

Retracted: Rapid diagnosis of cryptococcal meningitis by microscopic examination of centrifuged cerebrospinal fluid sediment.

The classic India ink test is positive in only half of cryptococcal meningitis cases, and reliable, rapid cryptococcal antigen (CRAG) testing requires technical expertise and facilities not always available. We therefore examined cerebrospinal fluid (CSF) sediment using May-Giemsa, periodic acid-Schiff, and Gram stains in 16 patients with cryptococcal meningitis. The India ink test was positive in seven patients (44%), while microscopic examination of sediment revealed cryptococci in 13 (81%); in six of these 13 the India ink test was negative. Both methods failed to detect the pathogen in the remaining three patients. CRAG testing in CSF was negative in two patients (one with acquired immunodeficiency syndrome, one with diabetes mellitus) whose India ink test also was negative while cryptococci were identified in their CSF sediment. No false positives occurred with CSF May-Giemsa staining in 27 cases of aseptic meningitis with negative cultures for Cryptococcus. In all, microscopic examination of centrifuged and stained CSF sediment proved more sensitive for rapid diagnosis of cryptococcal meningitis than the India ink method, and in two of our patients cryptococci were seen in centrifuged CSF sediment despite negative CRAG and India ink tests.

Adolescent↗