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PubMed1980

Endemic syphilis: transfer of resistance to Treponema pallidum strain Bosnia A in hamsters with a cell suspension enriched in thymus-derived cells.

Direct evidence for involvement of thymus-derived (T) cells in host defense against syphilitic infection is presented. Irradiated, bone marrow-reconstituted hamsters receiving cells from hamsters immune to infection with Treponema pallidum strain Bosnia A had significantly lower weights and fewer treponemes per lymph node than animals that had received normal lymphoid cells or only normal bone marrow cells. Cell suspensions enriched in T cells from immune hamsters were obtained by sequential filtration of pooled spleen and lymph node cells through glass- and nylon-wool columns. The fractionated suspensions of cells responded poorly to stimulation by phytohemagglutinin, Escherichia coli lipopolysaccharide, and dextran sulfate, but responded relatively strongly to the T-cell mitogen, convanavalin A. After fractionation the proportion of cells susceptible to antithymocyte serum and complement increased significantly. These immune cell suspensions depleted of bone marrow-derived cells closely resembled unfractionated suspensions in their ability to confer resistance to challenge with T. pallidium.

Animals↗
PubMed1998

Propofol preserves the viability of isolated rat hepatocyte suspensions under an oxidant stress.

UNLABELLED: The purpose of this study was to investigate whether propofol protects rat hepatocyte suspensions against an oxidant attack by a free radical generator 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH). Rat hepatocyte suspensions (2 x 10(6) cells/mL) were prepared using Seglen's collagenase perfusion technique. Suspensions were treated with AAPH (50 mM) alone, propofol (28 microM) plus AAPH, or, in a separate experiment, with either AAPH alone or 10% intralipid (0.5 microL/mL) plus AAPH. Each experiment had untreated control suspensions. Cell viability was measured at 1, 2, and 3 h using the trypan blue exclusion test and expressed as a percentage of the initial number of viable cells. Cells taken from control at time 0 h and each experimental group at 1 h from five separate hepatocyte preparations were examined by electron microscopy. Control cell viability decreased with time. The addition of AAPH significantly reduced viability compared with control (P < 0.0001); pretreatment with propofol significantly attenuated this effect at 1 h (P = 0.0008), but 10% intralipid had no effect. Electron microscopy revealed structural changes in cell membranes that could have accounted for the inability to exclude trypan blue. In conclusion, a 28-microM concentration of propofol protects rat hepatocytes from an oxidant stress sufficient to cause cell death at 1 h. IMPLICATIONS: Oxidants contribute to tissue injury in a variety of situations. We have shown that the anesthetic propofol improves survival of liver cells exposed to oxidant injury at blood concentrations achieved in anesthetized patients. These effects may be relevant during transplantation and critical illness.

Anesthetics, Intravenous↗
PubMed2002

Medial tarsal suspension: a method of elevating the medial lower eyelid.

PURPOSE: When attempting to elevate the lower eyelid for any reason, medial elevation is the most difficult to attain. Medial canthal tendon tightening creates mostly horizontal tension and contributes little vertical vector. We present a technique for applying a lifting force to the medial end of the eyelid: medial tarsal suspension. METHODS: The technique to suspend the medial lower eyelid tarsal plate to the superior orbital rim periosteum is described. The procedure, medial tarsal suspension (MTS), was performed on 38 lower lids of 24 patients. Adjunctive procedures, most commonly lateral canthal sling, were performed on 66% of the lids at the time of the initial medial tarsal suspension. The patients ranged in age from 29 years to 84 years. All had medial lower eyelid retraction, with facial nerve palsy, Graves eye disease, involutional lower eyelid retraction, and forms of muscular dystrophy the commonest etiologies. RESULTS: Thirty-one (82%) of the 38 MTS procedures were successful. There was no unifying factor among the seven failed procedures in five lids of five patients. Three of the five patients, including two who were operated on twice, ultimately had a successful MTS. This procedure was not repeated on the other two failed patients. Range of follow-up was 9 months to 5.6 years, with a mean of 3.7 years. The mean elevation of the central lower eyelid was 1.6 mm in the successful cases. CONCLUSIONS: Medial tarsal suspension is an effective way to elevate the medial end of the lower eyelid.

Adult↗
PubMedDate not supplied

Near wall concentration profiles of 1.0 and 2.5 microns beads during flow of blood suspensions.

A freeze-capture method was used to determine the concentration profiles of latex beads in the flow of blood suspensions at a wall shear rate of 400 s-1 in hollow fibers of 200 microns i.d. Bead diameters of 1.0 and 2.5 microns and suspension hematocrits from 15 to 80% were used. All profiles exhibited an excess of beads in the 20 microns closest to the wall and a uniform central concentration. Near-wall excesses greater than 2.5 times the central concentration occurred with suspensions having 2.5 microns beads when the hematocrit was 15-40%. Although large near-wall excesses sometimes occurred for the small beads and higher hematocrits, the usual event was a small near-wall excess. A Mann-Whitney-Wilcoxan test showed that the group of data for 2.5 microns beads in suspensions with hematocrits ranging from 15 to 40% was significantly different from all other data (p less than 0.0002). As the 2.5 microns beads approximate the average platelet, these data suggest that blood flows with physiologic hematocrits are associated with larger near-wall excesses of platelets than blood flows with elevated hematocrits.

Blood Physiological Phenomena↗
PubMed2001

Complications of static facial suspensions with expanded polytetrafluoroethylene (ePTFE).

BACKGROUND: Expanded polytetrafluoroethylene (ePTFE) is a synthetic porous material that has been used for static suspension in facial paralysis. It is manufactured in thin (1-mm or 2-mm) sheets that can be cut into strips and implanted through keyhole facial incisions. Regional deformities are addressed by multiple suspensions that provide cosmetic and functional therapy. The use of ePTFE eliminates donor site morbidity associated with the traditional harvest of fascia from either the temporal area or fascia lata. However, properties unique to this alloplast contribute to the complications that have occurred after its use in facial reanimation. OBJECTIVE: To describe complications with the use of ePTFE for facial suspension. SETTING: Academic medical center. METHOD: Retrospective chart review and review of literature. RESULTS: Six patients with facial paralysis who were treated with the ePTFE sling procedure had complications. Five slings failed because of stretch despite prestretching at implantation. One patient developed a late wound infection requiring removal of the sling. CONCLUSION: An ePTFE facial sling is an option for static facial suspension that can be therapeutic for patients with seventh nerve damage. There is a high rate of complications leading to revision surgery. Future studies are needed to evaluate alloplastic alternatives to ePTFE.

Adolescent↗
PubMed2003

Suspension laryngoscopy for endotracheal stenting.

OBJECTIVES/HYPOTHESIS: Airway stents have recently been used to establish and maintain patent airways in patients with malignant central airway obstruction, but insertion modalities remain controversial to date. The study seeks to determine the role of suspension laryngoscopy in interdisciplinary airway stenting. STUDY DESIGN: Retrospective, single-institution analysis of a case series treated by a multidisciplinary airway team. METHODS: Ninety-three consecutive patients with malignant obstruction of the trachea and/or tracheobronchial bifurcation underwent endotracheal stenting through a suspension laryngoscopy approach for the relief of impending respiratory distress. Feasibility, mortality, survival, and complications were analyzed as main outcome measures. RESULTS: Stenting through a suspension laryngoscopy approach was feasible 91 of 93 patients (97.8%). Fifteen patients needed repeated stenting, and in all, 121 stents were implanted during the observation period. This approach allowed for the repeated insertion of rigid bronchoscopes of graded sizes to establish an airway and for precise stent positioning. Optical instruments and stent introducer systems could easily be used while adequate ventilation was continuously maintained. Silicone stents of maximal size were inserted without injury of the vocal cords during intubation. Median survival for all patients was 8 months. No intraoperative airway complications were observed, and no patient died secondary to stenting. CONCLUSIONS: Suspension laryngoscopy and jet ventilation provide an ideal setting for the precise placement of tracheal and bifurcation airway stents. Laryngologists should actively participate in interdisciplinary airway stenting programs.

Airway Obstruction↗
PubMed1990

Needle suspension procedures for urinary stress incontinence: a review and historical perspective.

Armand J. Pereyra introduced a new approach in the treatment of female urinary stress incontinence which did not require abdominal retropubic dissection. This operation and subsequent modifications by Pereyra serve as the foundation for various needle suspension procedures. The reported cure rates for the Modified Pereyra Procedure and its variations have exceeded 85 per cent in several studies. There has been some suggestion of an increased late failure rate in the Modified Pereyra Procedure compared to abdominal retroubic urethropexy. Additional long-term studies are needed to answer this important question utilizing preoperative and postoperative urodynamic evaluation. Karram and Bhatia in their review of transvaginal needle bladder neck suspension procedures cited three studies which accomplished this in a total of 60 patients. It seems the popularity of needle suspension procedures continues to grow. Increasingly, needle suspension procedures have been used in the outpatient treatment of urinary stress incontinence. A continuing tribute to the operative contributions of Armand J. Pereyra in the treatment of urinary stress incontinence.

Female↗
PubMed1982

Breath suspension during the transcendental meditation technique.

We observed, over four independent experiments, 565 criterion-meeting episodes of breath suspension in 40 subjects practicing the Transcendental Mediation technique (TM), a simple mental technique involving no breath control procedures. The frequency and length of these breath suspension episodes were substantially and significantly greater for TM subjects than for control subjects relaxing with eyes closed. Voluntary control of respiration was most probably eliminated as an explanation of ths phenomenon by the experimental design and by the use of a variety of nonintrusive respiration transducers, including a two-channel magnetometer, an indirect but accurate means of monitoring respiration. Many TM subjects report experience of a completely quiescent mental state characterized by maintained awareness in the absence of thought. Eleven TM subjects were instructed to press an event mark button after each episode of this pure consciousness experience. The temporal distribution of button presses was significantly related (p less than 10(-10) to the distribution of breath suspension episodes, indicating that breath suspension is a physiological correlate of some, but not all, episodes of the pure consciousness experience. In an extensive study of a single advanced mediator, pure consciousness experiences were also associated with reduced heart rate; high basal skin resistance; stable phasic skin resistance; markedly reduced mean respiration rate, mean minute ventilation and mean metabolic rate; and statistically consistent changes in EEG power and EEG coherence (an indicator of long-range spatial order in the nervous system).

Adult↗
PubMed1998

Hypoglossal nerve injury caused by halo-suspension traction. A case report.

STUDY DESIGN: A case report of injury to the hypoglossal nerve (CN XII) resulting from the use of halogravity traction in a child with severe cervicothoracic kyphosis after an anterior and posterior spinal release. OBJECTIVE: To describe one of the potential dangers of halo-suspension (gravity) traction, which has not been reported previously in the orthopedic literature. SUMMARY OF BACKGROUND DATA: Cranial nerve injuries resulting from halo-skeletal traction are a recognized complication of such treatment, especially in patients with myelomeningocele. Halo-suspension traction using the patient's body weight as counter-traction has been recommended to provide a less rigid force and to reduce complications. METHODS: The authors report on the mechanism of injury and clinical course in a 12-year-old boy with myelomeningocele and a bilateral CN XII injury caused by halo-suspension traction from onset to resolution. RESULTS: This patient had dysphagia and difficulty swallowing 5 days after surgery. His wheelchair traction at this point was approximately 40% of his body weight. The traction was reduced, and a corticosteroid was administered. The patient's symptoms began to abate 5 days later. At 6 weeks after injury, his cranial nerve function was normal. CONCLUSIONS: Although halo-suspension traction or halo-wheelchair traction may be less rigid, injury to the hypoglossal nerve can be produced with traction exceeding 40% of body weight. In the patient in the current report, resolution of this injury was complete within 5 weeks, an outcome that is consistent with those of other reported cases of CN XII injury.

Adrenal Cortex Hormones↗
PubMed2005

Oropharyngeal complications of suspension laryngoscopy: a prospective study.

OBJECTIVE: This study was designed to evaluate the oropharyngeal complications of suspension laryngoscopy (SL). METHODS: We prospectively analyzed 56 consecutive SLs for intervention-related complications. Oropharyngeal symptoms and physical examination abnormalities were recorded before and after SL. SL-related problems were graded in severity and followed over time (weekly) until resolution was achieved. All patients had SL with either a gallows suspension or a manual technique and not a rotation-oriented (fulcrum) laryngoscope holding device. RESULTS: Oropharyngeal minor complications after SL occurred at a rate of 37.5%, and all these were temporary. No dental injuries occurred in the study cohort. There were no major complications after SL. Minor alterations related to taste occurred in 18% of the patients, 16% of patients had subjective swallowing complaints, and 12.5% had partial tongue numbness. Average duration of the post-SL complaints was 11 (6-34) days. A correlation between duration of suspension, size of laryngoscope, and risk of developing a minor oropharyngeal complication was present. CONCLUSION: SL carries a higher risk for lingual and glossopharyngeal nerve injuries than previously recognized. All of these complications were temporary. On the basis of comparison with historic data, SL by gallows suspension technique may pose a lower risk of dental injuries. This information should be used to improve preoperative SL patient education and informed consent.

Female↗
PubMedDate not supplied

The hammock suspension technique for hip spica cast application in children.

The hammock suspension technique for hip spica cast application in children utilizes a classic suspension system to support infants during application of the hip spica cast. The suspension system is simple and safe, and requires only readily available materials. The suspension system is exceptionally well-tolerated by infants. This technique was used in nine infants with femur fractures. All fractures healed. This technique requires a minimum of skilled assistance and proved useful in children under 2 years of age. This technique is suggested as an extremely practical method of performing this common orthopaedic procedure.

Casts, Surgical↗
PubMed1998

In situ detection of bacteria in continuous-flow cultures of seawater sediment suspensions with fluorescently labelled rRNA-directed oligonucleotide probes.

rRNA-targeted and fluorescently labelled oligonucleotide probes were used to study the composition of natural bacterial populations in continuous-flow cultures of seawater sediment suspensions. The cultures were run as enrichment cultures with increasing dilution rates, and hexadecane as the sole carbon source. Total cell numbers were analysed by counting DAPI (4',6-diamidino-2-phenylindole)-stained cells. To differentiate the population composition, oligonucleotide probes for eubacteria, for Cytophaga/Flavobacteria, and for four subclasses of the Proteobacteria (alpha, beta, gamma and delta) were used. About 40-80% of the DAPI-stained cells could be detected with the EUB338 probe. Moreover, it was possible to detect a shift in the composition of the natural bacterial population with increasing dilution rate of the continuous culture, from large amounts of Cytophaga/Flavobacteria to large numbers of members of the gamma-Proteobacteria. The cell recovery rate for bacteria labelled with specific oligonucleotide probes was analysed with defined cell numbers of Rhodospirillum rubrum, Comamonas testosteroni and Desulfovibrio vulgaris subsp. vulgaris introduced into the seawater sediment suspension, and was determined to be 13.9-33.5%. The standard deviation determined for this method applied to sediment suspensions was +/- 8.3%. The results suggest that the application of the in situ hybridization technique allows a good insight into the structure of populations growing in sediment suspensions.

Alkanes↗
PubMed2002

Stress fluctuations in sheared Stokesian suspensions.

We report an analysis, using the tools of nonlinear dynamics and chaos theory, of the fluctuations in the stress determined from simulations of shear flow of Stokesian suspensions. The simulations are for shear between plane parallel walls of a suspension of rigid identical spheres in a Newtonian fluid, over a range of particle concentration. By analyzing the time series of the stress, we find that the dynamics underlying these fluctuations is deterministic, low-dimensional, and chaotic. We use the dynamic and metric invariants of the underlying dynamics as a means of characterizing suspension behavior. The dimension of the chaotic attractor increases with particle concentration, indicating the increasing influence of multiple-body interactions on the rheology of the suspension with rise in particle concentration. We use our analysis to make accurate predictions of the short-term evolution of a stress component from its preceding time series, and predict the evolution of one component of the stress using the time series of another. We comment on the physical origin of the chaotic stress fluctuations, and on the implications of our results on the relation between the microstructure and the stress.

Journal Article↗
PubMed2003

Effect of particle inertia on turbulence in a suspension.

We propose a one-fluid analytical model for a turbulently flowing dilute suspension, based on a modified Navier-Stokes equation with a k-dependent effective density of suspension rho(eff)(k) and an additional damping term proportional, variant gamma(p)(k), representing the fluid-particle friction (described by Stokes law). The statistical description of turbulence within the model is simplified by a modification of the usual closure procedure based on the Richardson-Kolmogorov picture of turbulence with a differential approximation for the energy transfer term. The resulting ordinary differential equation for the energy budget is solved analytically for various important limiting cases and numerically in the general case. In the inertial interval of scales, we describe analytically two competing effects: the energy suppression due to the fluid-particle friction and the energy enhancement during the cascade process due to decrease of the effective density of the small-scale motions. An additional suppression or enhancement of the energy density may occur in the viscous subrange, caused by the variation of the extent of the inertial interval due to the combined effect of the fluid-particle friction and the decrease of the kinematic viscosity of the suspensions. The analytical description of the complicated interplay of these effects supported by numerical calculations is presented. Our findings allow one to rationalize the qualitative picture of the isotropic homogeneous turbulence of dilute suspensions as observed in direct numerical simulations.

Journal Article↗
PubMed2004

Microstructure in a settling suspension of hard spheres.

We report direct observations of the structure factor in a settling suspension, using numerical simulations based on a lattice-Boltzmann model of the fluid. We find that the horizontal density fluctuations in bounded suspensions are strongly suppressed by the settling process, vanishing as k(2) at long wavelengths. Our measurements of the structure factor confirm the qualitative predictions of one of several competing theories, although this theory does not yet explain why container walls are so important. Our results contradict the idea that a settling suspension is inevitably stratified by hydrodynamic dispersion at the suspension-supernatent interface.

Journal Article↗
PubMed2005

Thermal vitrification in suspensions of soft colloids: molecular dynamics simulations and comparison with experiments.

Dense suspensions of multiarm star polymers are known to develop liquidlike microstructure, which has been attributed to the similarities between high functionality stars and colloidal particles interacting via soft, long ranged potentials. Recent experimental studies reported a counterintuitive solidification of suspensions with f=128 , upon increase of the temperature in marginal solvents. We present our results from molecular dynamics simulations of dense suspensions of multiarm star polymers. Star polymers are modeled as "soft spheres" interacting via a theoretically developed potential of mean field. Our results show a transition towards a "glassy" state at a temperature very close to the one reported experimentally. The features of the transition are consistent with those of ideal glass transitions, as described by ideal mode coupling theory. Furthermore, our findings illustrate the road to vitrification for these soft-colloidal suspensions. Higher temperatures result in arm expansion that causes jamming and more than compensates for faster short time, temperature induced kinetics.

Journal Article↗
PubMed1988

Acid and alkaline invertases in suspension cultures of sugar beet cells.

Alkaline invertase was induced during the initiation of suspension cultures of single cells from leaf explants of sugar beets in Murashige-Skoog liquid medium which contained benzyladenine. This activity was barely detectable in the leaves themselves. In suspension cultures, the presence of both acid and alkaline invertases was detected; alkaline invertase was only present in the cytoplasm of the cultured cells, whereas acid invertase was present in the cytoplasm and cell walls, and was also detected in the culture medium. The cell wall contained at least three types of acid invertase; two of these activities were solubilized by saline (saline-released) and EDTA (EDTA-released), respectively, and the third remained tightly associated with the cell wall. Saline-released and EDTA-released invertases from the cell wall showed the significant differences in their properties: the saline-released enzyme had the highest affinity for sucrose among the invertases tested, and was easily bound to cell walls, to DNA, and to a cation exchanger, unlike the EDTA-released enzyme. Sucrose is the source of carbon for plant cells in suspension culture and is probably degraded in the cell wall by the saline-released invertase, which had the highest activity and the highest affinity for sucrose. Hexose products of this degradation would be transported to cytoplasm. Soluble invertase, EDTA-released invertase from the cell wall, and one of two extracellular invertases behaved similarly upon chromatography on DEAE-cellulose. They had similar activity profiles with changing pH, and similar K(m) values for sucrose. Thus it appears that they are identical. Two extracellular invertases found in the growth medium of the suspension cultures were probably identical with those in the soluble fraction of callus and seedlings of sugar beets, because they showed similar behaviors during chromatography on DEAE-cellulose, and had similar activity profiles with changing pH and K(m) values for sucrose.

Journal Article↗
PubMed1989

Effects of Singlet Oxygen Quenchers and pH on the Bacterially Induced Hypersensitive Reaction in Tobacco Suspension Cell Cultures.

Suspension cell cultures of Nicotiana tabacum L. inoculated with the incompatible pathogen Pseudomonas syringae pv pisi undergo a hypersensitive reaction. Addition of the singlet oxygen quencher bixin to cell suspensions had no effect on hypersensitive cell death. Addition of the singlet oxygen quencher 1,4-diazabicyclo octane (DABCO) increased the medium pH and delayed the onset of cell death. This delay was eliminated when cell suspensions were buffered, and could also be induced by increasing medium pH with KOH. Bixin and DABCO also did not suppress the hypersensitive reaction in tobacco leaves. These data do not support a role for singlet oxygen in the hypersensitive reaction. Medium pH, however, appears to be a critical factor in cell suspension cultures.

Journal Article↗