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PubMed2005

Fluorescent labeling of plant chromosomes in suspension by FISH.

By optimizing the concentration and time of treatment with hydroxyurea (HU), a DNA synthesis inhibitor, and trifluralin, a microtubule inhibitor, a highly effective (over 60%) cell cycle synchronization method for rye and barley meristem cells was developed. Chromosome suspensions containing highly purified and morphologically intact rye and barley chromosomes were prepared from the meristems of their root tips by homogenization. Digoxigenin-labeled 5S rDNA was used as a probe in FISH for the rye chromosomes in the suspension, and biotin-labeled 17S rDNA and centromeric DNA were used in FISH for the rye and barley chromosome suspensions, respectively. Bright signals were detected at the specific regions of interest on the chromosomes. The results indicate that the method developed in this study is useful for selection and sorting of chromosomes that are not distinguishable by other means, using specific fluorescent labeling by FISH of the chromosomes in suspension.

Chromosomes, Plant↗
PubMed1991

Absorption and multiple scattering by suspensions of aligned red blood cells.

The analytical theory of multiple scattering [J. Opt. Soc. Am. 60, 1084 (1970)] permits predictions of scattering patterns by homogeneous suspensions of aligned and randomly oriented particles. Predictions for randomly oriented particles have been tested previously. Using an optical system involving a He-Ne laser and suspensions of red blood cells, we tested the theory's predictions for scattering by suspensions in two distinct alignments. The qualitative effects of cell alignment on light scattering are consistent with those predicted, although measured differences in scattering between the two alignments exceed those predicted. We conclude that the theory may provide an optical means of distinguishing particle orientation in multiple scattering suspensions.

Absorption↗
PubMed1975

Effect of temperature during preparation of rat adrenal quarters and isolated cell suspension of their ACTH responsiveness.

The effect of temperature during preparation of rat adrenal quarters or isolated adrenal cell suspension on their response to ACTH was examined through a comparison of amounts of corticosterone produced after their incubation. The response to ACTH added in vitro was considerably higher when adrenal quarters and isolated adrenal cell suspension were prepared at room temperature (25 degree C) than when prepared at ice-cold. Endogenous steroidogenesis was not affected by the temperature. It seemed unlikely that this higher response to ACTH of adrenal quarters or isolated adrenal cell suspension prepared at room temperature was due to an activation of the cells. A possibility was discussed that cooling adrenal quarters or isolated adrenal cell suspension during the preparation may create an unphysiological state in some place to related the cell membrane.

Adrenal Glands↗
PubMed1988

Enzymes of adenosine metabolism in mouse sperm suspensions.

The enzymes of adenosine metabolism were investigated in suspensions of epididymal mouse spermatozoa incubated under conditions which support capacitation in vitro. High levels of adenosine deaminase activity were found in sperm suspensions, but the enzyme was located in the surrounding medium and was not intrinsic to spermatozoa. 5'-Nucleotidase was also present in the surrounding medium while in sperm cells it existed as an ecto-enzyme. Adenosine was not metabolized by washed spermatozoa under conditions used for the assay of adenosine deaminase or adenosine kinase, but it was metabolized rapidly by unwashed sperm suspensions. Incubation of sperm suspensions in conditions which modulate fertilizing ability resulted in small alterations in intrinsic 5'-nucleotidase activity of spermatozoa. In contrast, the activity of adenosine deaminase was not consistently modulated by such manipulations. Adenosine deaminase and 5'-nucleotidase exhibited similar kinetic parameters to enzymes from other sources and their activities were inhibited by coformycin and alpha, beta-methylene adenosine 5'-diphosphate, respectively. These studies highlight the low adenosine-metabolizing ability of spermatozoa coupled with the extensive metabolism in the medium which surrounds them. Extracellular adenosine metabolism can therefore occur and may modulate capacitation in vitro.

5'-Nucleotidase↗
PubMed2000

Effects of methylene blue, indigo carmine solution and autologous erythrocyte suspension on formation of adhesions after injection into rats.

The aim of this study was to determine whether autologous erythrocyte suspension can be used as a dye for evaluation of tubal patency and whether it has any advantages over methylene blue or indigo carmine solutions. Reproductively healthy female nulliparous Wistar Albino rats (n = 30), aged 6 months, mass 165-195 g, were assigned randomly to three groups. Rats received a 1 ml i.p. injection of 5% (w/v) methylene blue solution (methylene blue group: n = 10), 5% (w/v) indigo carmine solution (indigo carmine group: n = 10) or 5% (v/v) fresh autologous erythrocyte suspension (autologous erythrocyte group: n = 10). At 4 weeks after injection, a small sterile opening was made in the peritoneal cavity of each rat. The cavity was rinsed once with TCM-199 to collect macrophages. The rinsed peritoneal contents were cultured overnight to evaluate macrophage activation. The peritoneal opening was expanded for evaluation of adhesion formation. Only one rat from the autologous erythrocyte group had intra-peritoneal adhesions (score 2), whereas all rats in the methylene blue group (score 1: n = 1; score 2: n = 4; score 3: n = 4; and score 4: n = 1) and seven rats in the indigo carmine group (score 1: n = 1; score 2: n = 2; score 3: n = 3; and score 4: n = 1) had intra-abdominal adhesions. Macrophage activity was observed in the cultured peritoneal contents collected from the methylene blue and indigo carmine groups but not from the autologous erythrocyte group. Adhesion formation could be due to macrophage activation caused by methylene blue and indigo carmine solutions. These results indicate that tubal patency can be observed by laparoscopy using autologous erythrocyte suspension. The results of this study are believed to be the first to indicate that a patient's own erythrocyte suspension could be used during observation of tubal patency by laparoscopy. However, further studies are required.

Animals↗
PubMed1999

Atovaquone suspension in HIV-infected volunteers: pharmacokinetics, pharmacodynamics, and TMP-SMX interaction study.

STUDY OBJECTIVE: To evaluate the pharmacokinetics and safety of atovaquone suspension in volunteers infected with the human immunodeficiency virus ((HIV). DESIGN: Open-label, nonrandomized study. SETTING: Two clinical research centers. PATIENTS: Twenty-two HIV-infected volunteers with a median CD4 cell count of 37 cells/mm3. INTERVENTIONS: Patients received atovaquone suspension fasting or fed for 2-week periods with crossover at dosages of 500 mg/day, and randomization to fasting or fed at dosages of 750 and 1000 mg/day. A subset of patients also received 750 mg twice/day with food, and a subset of those who received 1000 mg/day fasting also received 1000 mg with food. During a long-term dosing phase, a subset of subjects were evaluated for an interaction between atovaquone and trimethoprim-sulfamethoxazole (TMP-SMX). MEASUREMENTS AND MAIN RESULTS: Average steady-state atovaquone concentrations at 500 mg were 6.7 +/- 3.2 microg/ml fasted and 11.3 +/- 5.0 microg/ml with food; at 750 mg, 9.9 +/- 7.1 microg/ml fasted and 12.5 +/- 5.9 microg/ml with food; at 1000 mg, 9.7 +/- 4.3 microg/ml fasted and 13.6 +/- 5.0 microg/ml with food; and at 1500 mg, 21.1 +/- 5.0 microg/ml with food. Thus, plasma concentrations were not proportional to dose. Concomitant food ingestion resulted in a 1.3- to 1.7-fold increase in values. Average steady-state concentrations were less than 10 microg/ml in 21% and more than 15 microg/ml in 36% of patients at 1000 mg/day with food; at 750 mg twice/day, all five patients had levels above 15 microg/ml. Atovaquone suspension was well tolerated; diarrhea, nausea, fatigue, and rash were the most common adverse events. Concomitant administration of TMP-SMX did not change atovaquone concentrations and resulted in small decreases in concentrations of TMP (16%) and SMX (10%). CONCLUSION: Plasma concentrations are significantly higher when atovaquone suspension is administered with food compared with fasting. Total doses of 1500 mg/day are likely to achieve concentrations effective for prophylaxis of Pneumocystis carinii pneumonia.

AIDS-Related Opportunistic Infections↗
PubMed1979

Filtrability and flow characteristics of leukemic and non-leukemic tumor cell suspension through polycarbonate filters in relation to hematogenous spread of cancer.

Tumor cell suspension was filtered through Nuclepore filters of various pore diameters (5.4, 7.9 and 9.3 micron) with positive pressure from 5 to 60 cmH2O at 37 degrees C. The mean diameters of tumor cells of 6 strains ranged from 10.6 to 13.6 micron. Cell suspension of each tumor strain was filtered with characteristically different time. No significant difference was observed among tumor strains in the percentage of cells filtered. The cell viability was almost unchanged by filtration. The filtration time was considered to indicate the passing ability of tumor cells through capillary pores. Leukemic cells such as DBLA 1, DBLA 6 and L 1210 were relatively small in diameter and possessed a high passing ability compared with other non-leukemic tumor cells such as Yoshida sacroma, AH 109A and AH 100B. The relationship between pressure and flow rate of the cell-free solution was linear, while the pressure-flow rate curves of the tumor cell suspension were convexed to the pressure-axis at low pressure and became linear over the pressure of the yield point. Rheologically, the yield point and the reciprocal of the slope indicate structural viscosity and apparent viscosity of the cell suspension, respectively, they are considered to reflect the rheological properties of tumor cells. Comparing these parameters of the curves in filters of different pore diameters, the viscosity of leukemic cells appeared to be the lowest and the structural viscosity of AH 100B cells was the highest among the tumor strains examined. The distribution and frequency of metastases following intravenous transplantation of these tumor cells suggested that the passing ability of tumor cells plays an important role in organ preference of hematogenous metastasis and leukemic state in leukemia.

Animals↗
PubMed2004

Differentiation of human embryonic stem cells to dopaminergic neurons in serum-free suspension culture.

The use of human embryonic stem cells (hESCs) as a source of dopaminergic neurons for Parkinson's disease cell therapy will require the development of simple and reliable cell differentiation protocols. The use of cell cocultures, added extracellular signaling factors, or transgenic approaches to drive hESC differentiation could lead to additional regulatory as well as cell production delays for these therapies. Because the neuronal cell lineage seems to require limited or no signaling for its formation, we tested the ability of hESCs to differentiate to form dopamine-producing neurons in a simple serum-free suspension culture system. BG01 and BG03 hESCs were differentiated as suspension aggregates, and neural progenitors and neurons were detectable after 2-4 weeks. Plated neurons responded appropriately to electrophysiological cues. This differentiation was inhibited by early exposure to bone morphogenic protein (BMP)-4, but a pulse of BMP-4 from days 5 to 9 caused induction of peripheral neuronal differentiation. Real-time polymerase chain reaction and whole-mount immunocytochemistry demonstrated the expression of multiple markers of the midbrain dopaminergic phenotype in serum-free differentiations. Neurons expressing tyrosine hydroxylase (TH) were killed by 6-hydroxydopamine (6-OHDA), a neurotoxic catecholamine. Upon plating, these cells released dopamine and other catecholamines in response to K+ depolarization. Surviving TH+ neurons, derived from the cells differentiated in serum-free suspension cultures, were detected 8 weeks after transplantation into 6-OHDA-lesioned rat brains. This work suggests that hESCs can differentiate in simple serum-free suspension cultures to produce the large number of cells required for transplantation studies.

Animals↗
PubMed1996

Pharmacokinetic evaluation of omeprazole suspension following oral administration in rats: effect of neutralization of gastric acid.

In order to evaluate a clinical use of omeprazole suspension, we examined the pharmacokinetics of omeprazole after oral administration in rats. Although the administration of omeprazole suspension buffered by NaHCO3 solution did not produce a significant increase in the area under the concentration-time curve (AUC) value compared with non-buffered group, the administration of NaHCO3 buffer immediately after dosing of omeprazole suspension buffered by NaHCO3 caused a significant increase in the AUC value. These results suggest that the NaHCO3 treatment following the administration of omeprazole buffered suspension effectively decreased the degradation of the compound by gastric acid. Therefore, the successive administration of NaHCO3 solution after the omeprazole dosing seems to be a simple and useful method for the administration to patients who cannot receive tablets.

Administration, Oral↗
PubMed2004

Multichannel apparatus for parallel monitoring of light scattering in Dictyostelium discoideum cell suspensions.

Suspensions of Dictyostelium discoideum amoebae display free-running light scattering oscillations at the onset of development. We describe a device to monitor these oscillations in several samples in parallel. The apparatus consists of a thermostated cuvette holder where up to eight cuvettes containing cell suspension are inserted. Cells are aerated and kept in suspension via an airlift. Infrared light emitted from a five-diode array passes through the suspension and is detected by an array of five light detecting diodes. The resulting signal is digitized and recorded with a sampling rate of two measuring points/second. The parallel analysis approach allows determination of the effects of adding of agents or of variations in the external conditions in the same batch of amoebae at the same developmental time point. This represents an advantage over the conventional single cuvette approach, as oscillation characteristics themselves are developmentally regulated. Moreover, as the new experimental setup enables simultaneous analyses of up to eight samples, the behavior of wild-type and several mutant strains can be compared under identical experimental conditions.

Animals↗
PubMed1991

Effect of suspension hypokinesia/hypodynamia on tissue protein turnover in rats.

The effect of suspension hypokinesia/hypodynamia on the protein metabolism in skeletal muscles (gastrocnemius and soleus) and visceral organs (liver and small intestine) was investigated in the rat. Suspension for 10 days resulted in atrophy of the visceral organs as well as the skeletal muscles, which was associated with decreases in the amounts of visceral and muscle protein. There was marked breakdown of muscle protein, which was reflected by increases in the urinary excretion of N7-methylhistidine and cathepsin D activity. Measurement of protein synthesis by the L-[4-3H]phenylalanine method revealed that the synthesis in the gastrocnemius, but not in the soleus, muscle was suppressed on suspension for 10 days. Thus, both the increased catabolism and decreased synthesis of protein in the muscles may be causally related to the muscle atrophy occurring in suspension. In the visceral organs, on the other hand, the protein synthesis was found to increase in hypokinetic rats. Moreover, the concentration of visceral protein was also increased, despite the decreased amount of muscle protein. These changes in protein metabolism in the liver and small intestine may explain, at least partly, the slightly positive nitrogen balance which was observed after long-term weightlessness.

Animals↗
PubMed1987

Magnetite albumin suspension: a superparamagnetic oral MR contrast agent.

Suspensions of magnetite albumin microspheres (MAM), a new biodegradable particulate iron superparamagnetic MR contrast material, were evaluated in vitro and in vivo as an oral contrast agent. MAM is stable over a broad range of pH and tolerates proteolytic enzyme exposure over 24 hr in vitro. MAM possesses a much larger magnetic moment than do paramagnetic contrast agents. The transverse relaxation rate (R2) of MAM can be as much as 40 times the longitudinal relaxation rate (R1). In vitro spectroscopy studies confirm the potency of MAM in promoting T2 relaxation at concentrations of 10-1000 mg/l. Preliminary studies in rabbits and dogs show that in contrast to oral gadolinium-DTPA, which causes increased signal in bowel, MAM causes marked signal loss in the stomach and small bowel on both T1- and T2-weighted pulse sequences. Radionuclide labeling studies of MAM suspension with 99mTc show no evidence of absorption of MAM suspension from the gastrointestinal tract in small animals. Superparamagnetic suspensions such as MAM that reduce bowel signal on T1- and T2-weighted pulse sequences offer the unique benefit of reducing motion artifacts throughout the gastrointestinal tract, which should allow for improved evaluation of intra- and retroperitoneal diseases, particularly with high-field strength and gradient-echo "fast-scan techniques." Unlike paramagnetic material, MAM appears effective as a small-bowel contrast material.

Administration, Oral↗
PubMed2004

Passive flow through an unstalked intertidal ascidian: orientation and morphology enhance suspension feeding in Pyura stolonifera.

Passive flow is believed to increase the gains and reduce the costs of active suspension feeding. We used a mixture of field and laboratory experiments to evaluate whether the unstalked intertidal ascidian Pyura stolonifera exploits passive flow. We predicted that its orientation to prevailing currents and the arrangement of its siphons would induce passive flow due to dynamic pressure at the inhalant siphon, as well as by the Bernoulli effect or viscous entrainment associated with different fluid velocities at each siphon, or by both mechanisms. The orientation of P. stolonifera at several locations along the Sydney-Illawarra coast (Australia) covering a wide range of wave exposures was nonrandom and revealed that the ascidians were consistently oriented with their inhalant siphons directed into the waves or backwash. Flume experiments using wax models demonstrated that the arrangement of the siphons could induce passive flow and that passive flow was greatest when the inhalant siphon was oriented into the flow. Field experiments using transplanted animals confirmed that such an orientation resulted in ascidians gaining food at greater rates, as measured by fecal production, than when oriented perpendicular to the wave direction. We conclude that P. stolonifera enhances suspension feeding by inducing passive flow and is, therefore, a facultatively active suspension feeder. Furthermore, we argue that it is likely that many other active suspension feeders utilize passive flow and, therefore, measurements of their clearance rates should be made under appropriate conditions of flow to gain ecologically relevant results.

Analysis of Variance↗
PubMed1985

The effects of vaginal repair on anterior bladder suspension defects. A radiological and clinical evaluation.

In 22 patients with anterior bladder suspension defect as judged by colpocysto-urethrography (CCU) a vaginal repair was undertaken. In 14 patients urinary stress or urge and stress incontinence was the indication for operation, and in 8, genital prolapse. At follow-up more than 6 months postoperatively the CCU was repeated and a clinical evaluation undertaken. A normalization of the CCU was obtained in only 6 patients and 10 showed a less severe suspension defect. Nine of 14 patients were cured of incontinence. Only 3 of these had a normal follow-up CCU. Improvement of bladder suspension defect was not the sole responsible factor for postoperative continence. Urinary incontinence developed postoperatively in 2 of 8 patients operated on solely because of symptomatic genital prolapse. Very high cure rates for urinary incontinence have been reported following a colposuspension operation. A vaginal repair is not recommended as first-choice operation in incontinent females with anterior bladder suspension defects, if a CCU may be undertaken and the colposuspension technique is mastered.

Adult↗
PubMed1993

A modified Raz bladder neck suspension operation. Results of a one to three years follow-up investigation.

OBJECTIVE: Long term follow-up study of stress incontinence operations shows a declining success rate in time, especially for the needle suspension technique. We evaluated the long term results of a modified bladder neck suspension operation. METHODS: From 01-12-87 till 01-12-89 a total of 42 modified Raz bladder neck suspensions for stress incontinence were performed. Early evaluation at three months had shown a cure rate of 93%. Long term (mean 27 months) results were evaluated using a questionnaire. RESULTS: Follow-up of 41 patients showed that ten patients (24%) were cured. Fourteen (34%) considered their situation improved and acceptable, despite mild incontinence. Seventeen patients (40%) considered their situation still unacceptable, half of them (nine patients, 21%) had another operation for incontinence done within two years. CONCLUSIONS: We conclude that this one to three years follow-up shows that the modified Raz bladder neck suspension, in our hands, has, in spite of a good short term result, a relatively low long term success rate.

Adult↗
PubMed1995

Normal ciliary beat frequency after ciliogenesis in nasal epithelial cells cultured sequentially as monolayer and in suspension.

Ciliary beat frequency (CBF) was measured at room temperature in nasal epithelial cells from 10 control individuals at multiple time points during sequential monolayer-suspension culture. CBF was 8.4 +/- 1.6 Hz in the biopsy and decreased in monolayer culture to approximately 6 Hz. During monolayer culture the interindividual variability was increased (3.0 Hz), but not the intercellular and intracellular variability. Immediately after ciliogenesis in suspension culture, CBF was approximately 8 Hz, with a low interindividual variability. After 3 weeks in suspension culture CBF was 8.6 +/- 0.9 Hz. There was no difference in intercellular and intracellular variability of CBF in the different culture conditions. Ciliogenesis in the sequential monolayer-suspension culture results in quantitative normal ciliary activity, with low variability. The most important parameter of ciliary activity that changes during ciliary deterioration and ciliogenesis is the CBF itself.

Cell Membrane↗
PubMed1988

Stereotaxic implantation of dispersed cell suspensions into brain. A systematic appraisal of cell placement and survival.

The application of several recent advances in cell biology, brain implantation, and cell-mediated tumor immunotherapy requires successful and reproducible placement of viable cell suspensions into brain. Stereotaxic implantation is being used to inject cytotoxic lymphocytes into gliomas and to replace dopaminergic cells in parkinsonian models. Systematic assessment of the factors that influence success in implantation of cell suspensions into solid tissues is needed. A model was developed for investigation of stereotaxic implantation using radiolabeled rat lymphokine-activated killer (LAK) cells. Anesthetized rats received microliter injections of cell suspension into the right caudate nucleus. The injection volume, cell concentration, infusion rate, and needle size were varied systematically. The animals were sacrificed 1 hour after injection; the brain was removed and sectioned, and the radioactivity was counted. Three aliquots of the suspension were injected into counting tubes for control analysis. Recovery of radioactivity was expressed as the percent of mean counts per minute (cpm) in the right frontal lobe/mean cpm in the three control tubes. To assess the viability of implanted cells, the right frontal region was mechanically dissociated in media and centrifuged, and the pellet and supernatant were counted. By using small needles and slow infusion of volumes of 10 microliters or less, 85% to 90% of the radioactivity was recovered in the caudate nucleus. At least half of the implanted cells were viable. Consistent, accurate implantation of dispersed cells into brain over a range of volumes, cell concentrations, infusion rates, and needle sizes was achieved.

Animals↗
PubMed1983

Action of hydroxyethyl starch on the flow properties of human erythrocyte suspensions.

Hydroxyethyl starch (HES) has often been used as a plasma expander, but questions still remain concerning the mechanisms by which it produces changes in the rheological properties of blood and erythrocyte (RBC) suspensions under various flow conditions. The present investigation has shown that the dynamic viscosity of HES (232,000 and 565,000 daltons) solutions rises in a nonlinear fashion with increasing HES concentration, and for a given concentration of HES exhibits Newtonian behavior at shear rates between 0.15 to 124 sec-1. At low (less than 0.9 sec-1) shear rates the apparent viscosity of a 40% RBC suspension increases with lower concentrations of HES because of RBC aggregation. At higher concentrations of HES, increases in suspension viscosity are due to an increase in the viscosity of the continuous phase since the RBC are largely disaggregated. At high (greater than 36 sec-1) shear rates the relative viscosity (eta/eta O) of RBC suspensions slowly decreases with increasing HES concentration. At low shear rates eta/eta O increases and then decreases with increasing HES concentration. Evidence of the concentration-dependent effects of HES on RBC aggregation is provided not only by the viscometric analysis but also from measurements of erythrocyte sedimentation rate (ESR) and the zeta sedimentation ratio (ZSR). HES is a more potent aggregating agent in phosphate buffered saline (PBS) than it is in plasma. Polymer size has only a slight effect on the extent of RBC aggregation produced, but does have a significant effect on the concentration of polymer at which maximum aggregation occurs. The viscosity-corrected electrophoretic mobility of RBC in HES rises monotonically with the concentration of HES in the suspending medium. Decreases in the extent of RBC aggregation with increasing polymer concentrations probably result from an increase in the electrostatic repulsive forces between the cells.

Blood Sedimentation↗