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PubMedDate not supplied

Polyvinyl alcohol particle size and suspension characteristics.

PURPOSE: To evaluate the size and shape of commercially available polyvinyl alcohol (PVA) particles and to determine whether they change in size when suspended in nonionic contrast and in a solution of nonionic contrast and absolute alcohol. METHODS: The two-dimensional area and the long and short axis of PVA particles from several different vendors were measured using a light microscope attached to a video system and an image-processing software program. Particles were measured as packaged (dry or suspended in saline), suspended in ioversol, and suspended in ioversol containing 30% alcohol. RESULTS: All brands of dry particles had similar microscopic appearances. The saline-suspended particles had fewer and finer perforations. After suspension in contrast, all sizes and brands of dry particles significantly increased in size. The particles packaged in saline did not expand. The addition of alcohol to the contrast did not consistently change particle size. Particle aggregation was similar in both contrast suspensions for all groups of particles. Particles less than 50 microns in size were rarely observed in any PVA preparation after suspension. CONCLUSIONS: The three dry PVA preparations seem to be similar. All increase significantly in size when suspended in nonionic contrast or contrast-alcohol solutions. The saline-packaged PVA particles were different from the dry variety and did not enlarge in contrast or contrast-alcohol solutions. Alcohol did not change the size or suspension characteristics of PVA particles. Particles less than 50 microns in size were rarely identified.

Contrast Media↗
PubMed1995

[A new biomaterial in surgery of ptosis with frontalis suspension: wide pore PTFE].

BACKGROUND: In brow suspension, there is agreement that fresh tissue (autogenous fascia lata or temporalis fascia) provides the best results in terms of low complications and duration of the effect. Yet, the morbidity of fresh tissue harvesting is not negligible. Many alternative materials have disadvantages in terms of duration of the procedure and side effects. METHODS: We have used a new material: wide porous expanded polytetrafluoroethylene (eP.T.F.E.). This material is an inert vitreous teflon alloplast with a high biocompatibility. It is close to Gore-Tex, but differs from it by a higher porosity (over 90%) and wider diameter of its pores (over 50 mus). We performed a series of 60 brow suspension from February 1992 to March 1994, using this new material. RESULTS: We did not encounter any significant complications due to the material and in circumstance, we did not deplore any migration, infection or extrusion of the ePTFE. The biocompatibility seems to be increased, as it has been demonstrated by light and electron microscopy of the implanted material who revealed that fibrovascular ingrowth was significantly achieve two months after surgery. CONCLUSION: The first results of this series are very encouraging. They can favourably be compared with the results of other series using different types of materials available in brow suspension. Though our longest follow-up is 30 months, further study is necessary to evaluate the long term results and eventual long term side effects of ePTFE, which avoid harvesting fresh tissues, thus reducing the brow suspension procedure's morbidity.

Adolescent↗
PubMed1994

Suspension-mediated induction of Hepa 1c1c7 Cyp1a-1 expression is dependent on the Ah receptor signal transduction pathway.

We have recently demonstrated that release of normal human epithelial cells from cell-substratum and/or cell-cell adhesion generates cellular signals that induce the expression of CYP1A1 in the absence of xenobiotic polycyclic aromatic hydrocarbons (Sadek, C. M., and Allen-Hoffmann, B. L. (1994) J. Biol. Chem. 169, 16067-16074). To directly test the involvement of the Ah receptor signal transduction pathway in CYP1A1 induction following suspension of epithelial cells, we analyzed wild-type Hepa 1c1c7 cells, a subclone of the Hepa-1c1 mouse hepatoma line, and two mutant Hepa 1c1c7 lines, Class I and Class II. Suspension of wild-type Hepa 1c1c7 cells for 4 h led to an induction of steady state levels of CYP1A1 mRNA, similar to that obtained following treatment of adherent cells with 10(-9) M 2,3,7,8-tetrachlorodibenzo-p-dioxin. Mutants of the Hepa 1c1c7 cells defective in different aspects of the Ah receptor signal transduction pathway exhibited negligible (Class I) or no (Class II) suspension-mediated induction of CYP1A1 mRNA. Gel mobility shift analysis of nuclear extracts from suspended or 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated wild-type cells showed that both treatments produced identical shifts in the mobility of an XRE-containing probe. Antibody supershift experiments confirmed that the Ah receptor was a component of the DNA-protein complex from suspended wild-type Hepa 1c1c7 cells. These data directly demonstrate that suspension of wild-type Hepa 1c1c7 cells leads to nuclear localization and activation of the Ah receptor to a DNA-binding form.

Animals↗
PubMed1994

Use of Gore-Tex sling in brow suspension procedure.

A variety of materials have been employed for brow suspension surgery for ptosis. Gore-Tex (expanded polytetrafluoroethylene ePTFE) has been used as vascular prosthesis. We have used cylinder Gore-Tex in brow suspension surgery for 15 ptotic eyelids (11 patients), including 10 eyes (8 patients) of congenital ptosis, 1 eye of traumatic ptosis in a young male, and 4 eyes (2 patients) of myogenic ptosis in elderly patients. All of the eyelids had minimal or absent levator muscle function, and drooped to cover the visual axes. The surgical technique for the 10 congenital ptotic eyelids was a modified Fox's method. The remaining 5 adult eyelids were operated by a modified Crawford's method, with interlocking of the two suspension bands at the lower apex of each triangle and direct suturing of the bands to the tarsal plate. The use of Gore-Tex in brow suspension makes it easy to adjust the height and contour of the operated eyelids. Patients were followed-up from 2 to 16 months (average 9.1 months) postoperatively. The only complication was granuloma formation at the most upper knot area in 5 patients (6 eyelids), one of which also had granuloma at the ipsilateral fornix with the Gore-Tex band cutting through the conjunctiva. One eyelid drooped due to knot granuloma and infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Clonal analysis of rat tibia growth plate chondrocytes in suspension culture--differential effects of growth hormone and insulin-like growth factor I.

The number of growth hormone (GH) receptors in cultured rat epiphyseal chondrocytes are increased with numbers of cell divisions in monolayer. We wanted to study if increased number of cell divisions in monolayer influence GH or insulin-like growth factor I (IGF-I) response in a subsequent suspension culture. Primary isolated chondrocytes from rat tibia growth plates were cultured in monolayer at different seeding densities (4000, 8000 and 24,000 cells/cm2). After a culture period of 7 days, cells were trypsinized, counted and subcultured at 50,000 cells per dish in suspension stabilized with 0.5% agarose. 14 days later the agarose cultures were dried, stained and the number of clones with a diameter exceeding 50 microns was counted. Individual clones were classified as undifferentiated or differentiated according to the following criteria: cell clusters with a diameter of 50 microns and without matrix staining were classified as undifferentiated; cell clusters with a diameter over 50 microns consisting of 4 cells or more and with matrix stained by Alcian Blue were classified as differentiated clones. Human growth hormone (hGH) added to the suspension culture medium increased the number of undifferentiated clones if cells had been precultured at 4000 and 8000 cells/cm2 but hGH had no stimulatory effect on either clone type at 24,000 cells/cm2. IGF-I significantly increased the number of differentiated clones at all seeding densities while no effect was demonstrated on the number of undifferentiated clones. The results from the present study suggest that an increased number of cell divisions during primary monolayer culture increases GH responsiveness in a subsequent suspension culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Do changes in cell shape affect suspension conductivity?

The conductivity of a suspension containing uniformly oriented asymmetric cells depends on the shape of the cells. Whether the shape of cells with random spatial orientation also affects the conductivity of a suspension is not clear. A highly sensitive apparatus was used to register the dynamic changes in conductivity of erythrocyte suspension, upon induced morphological transformation discocytes<-->spherocytes). The results obtained with a sensitivity of up to 0.06% show that the drastic change of cell shape itself did not affect the suspension conductivity.

Electric Conductivity↗
PubMed1996

The gasless laparoscopic Burch bladder neck suspension: early experience.

PURPOSE: We evaluated the gasless extraperitoneal laparoscopic Burch bladder neck suspension. MATERIALS AND METHODS: This retrospective study included 47 patients with type II stress urinary incontinence treated sequentially with this technique between September 1994 and September 1995. Balloon dissection was used to develop the extraperitoneal space. A mechanical retraction system was used with conventional laparotomy instruments to perform laparoscopic Burch bladder neck suspension. RESULTS: Of the 47 patients who underwent this procedure 3 (6%) required conversion to an open operation. Obesity and previous pelvic surgery were not contraindications to this technique. The only major complication involved blood loss necessitating conversion to an open operation. Average operative time was 96.4 minutes and average hospital stay was 3.5 days. Followup at 2 to 15 months (mean 8.2) indicated successful results (that is no pads were required) in 44 patients (90%). CONCLUSIONS: Gasless laparoscopic bladder neck suspension has a lower open surgery rate, and may be performed more rapidly than conventional carbon dioxide laparoscopic Burch bladder neck suspension. Previous multiple operations and obesity are not contraindications to the technique.

Adult↗
PubMedDate not supplied

[Kinetics of lipid peroxidation induced by Fe2+ ions in a suspension of mitochondrial and nuclear membranes].

Kinetics of TBARS accumulation, Fe2+ oxidation, and chemiluminescence were measured in nuclear and mitochondrial membrane suspensions during Fe(2+)-induced lipid peroxidation development. Above certain critical Fe2+ concentrations ([Fe2+].) the latent period (t) of lipid peroxidation development were observed. By using the dependence of t on [Fe2+] the [Fe2+]. values were measured in nuclear and mitochondrial membrane suspensions. At the same concentrations of nuclear and mitochondrial membranes (1 mg/ml) the [Fe2+] value changed from 10 to 30 mu kM. In the case of nuclear membrane suspension the [Fe2+] value changed from 20 to 30 mu kM with the change of membrane concentrations from 0.5 to 1.5 mg/ml. For mitochondrial membrane suspension [Fe2+]. value increased from 10 to 40 mu kM with increasing membrane concentrations from 1 to 4 mg/ml. Apparently, [Fe2+]. value is the main parameter determining the kinetics of Fe(2+)-induced lipid peroxidation in native membrane preparations; the [Fe2+]. value in different membrane systems, in turn, is dependent on the ability of the membrane to bind Fe2+ ions.

Animals↗
PubMed1996

Endovascular embolization with self-made silk segment suspension in a rabbit model.

OBJECTIVE: To evaluate the efficacy and the histologic changes caused by self-made silk segment suspension as an agent for endovascular embolization of the external carotid artery of rabbit. METHODS: Three different silk suspension were used to perform selective endovascular embolization of the external carotid artery in 21 rabbits. Postembolization changes were investigated by angiography, light and electron microscopy, and behavioral and functional examination made in various groups of rabbits. RESULTS: The vascular changes in the group of simple silk segment were limited. The intima became thinner, while the media and adventitia were intact. However, in groups of ethanol-or estrogen-soaked silk segments, there was evident destruction of all layers of the vascular wall, including the intima, the media and the adventitia. CONCLUSIONS: Estrogen- or ethanol-soaked silk suspension is ideal and reliable for endovascular embolization, with the former being more effective than the latter. The obliteration caused by the suspension of simple silk segment was due to mechanical packing and compression plus incomplete thrombosis, which is likely to result in recurrence through compensatory collateral circulation.

Animals↗
PubMed1995

Anterior vaginal suspension for vaginal vault prolapse.

Vaginal prolapse may occur following hysterectomy or may evolve with the uterus in place. Current treatment options for vaginal prolapse have a limited success rate or are associated with significant morbidity. In this retrospective review, we present our experience with a new procedure for repair of vaginal prolapse. This technique relies on anterior suspension of the vaginal vault to the anterior rectus sheath in a fashion similar to bladder neck suspension. Forty patients have undergone this procedure. All patients had vaginal prolapse, cystocele, and urinary incontinence. In addition, 34 patients had enterocele, six had uterine prolapse, 33 had rectocele, and two had urethral diverticula. All patients had anterior vaginal suspension (AVS), with cystocele repair and bladder neck suspension. Six patients had vaginal hysterectomy, 34 had enterocele repair, 33 had rectocele repair, and two had urethral diverticulectomy. The mean hospital stay was 2.5 days (range, 1-7 days), and their mean follow-up was 30 months (range, 12-54 months). Thirty-six (90%) patients have excellent support of the vagina with no evidence of recurrent cystocele, enterocele, or rectocele. Four (10%) patients have recurrent enterocele. Thirty-three (82.5%) patients are dry or have rare episodes of urinary incontinence (less than one episode/month), whereas four (10%) patients have recurrent stress incontinence and three (7.5%) have urge incontinence. Constipation and fecal incontinence were resolved in all patients. All patients who were sexually active preoperatively remained so postoperatively, and none reported dyspareunea. Vaginogram in 10 patients demonstrated that posterior angulation of the vaginal axis was retained in all patients. AVS is associated with an excellent success rate in terms of resolution of symptoms and correction of prolapse. Morbidity is minimal, and hospital stay is short. The technique is simple and relies on anatomy that is familiar to all urologists. In addition, the vaginal approach allows for simultaneous correction of all components of vaginal prolapse and any associated vaginal pathology.

Adult↗
PubMed1997

Stress urinary incontinence. Laparoscopically assisted transvaginal needle suspension.

OBJECTIVE: To characterize laparoscopically assisted transvaginal needle suspension for stress urinary incontinence and describe the authors' initial experience with this approach. STUDY DESIGN: A retrospective analysis was performed on 19 cases of stress urinary incontinence treated with this technique. All patients were evaluated at least one year postoperatively. RESULTS: Laparoscopically assisted transvaginal needle suspension was successfully completed in all 19 cases. No procedure required conversion to laparotomy. No intraoperative morbidity attributable to prevesical dissection was noted. Average operating time for needle suspension was 25 minutes, and average blood loss was 50 mL. No postoperative infectious or hemorrhagic morbidity was noted. All patients were subjectively cured of incontinence one year postoperatively, although two patients experienced transient urinary retention, and one experienced transient detrusor instability within the first three postoperative months. CONCLUSION: This approach allows accurate, visually guided placement of suspension sutures and may induce extraperitoneal scarring similar to retropublic colposuspension. These factors may result in long-term cure rates comparable to those of retropublic colposuspension without the need for endoscopic suturing.

Female↗
PubMedDate not supplied

[Dependence of microwave produced heating of cell suspensions on their concentration].

The kinetics of microwave (7 GHz) heating of yeast and bacterial cell suspensions of different concentrations was investigated in the conditions of various thermoisolation of irradiated samples. It was established that independently of type of microorganisms, microwaves produced a more intensive heating of cell suspension in comparison with suspension fluid. The degree of heating was shown to increase with cell concentration. This effect was more expressed under conditions of thermoisolation. At the same irradiation doses and cell concentrations the yeast suspension was heated more vigorously than bacterial one. These differences disappeared when the rise in sample temperature was related to the total cell volume.

Escherichia coli↗
PubMed2002

Proteomic analysis of rat soleus muscle undergoing hindlimb suspension-induced atrophy and reweighting hypertrophy.

A proteomic analysis was performed comparing normal rat soleus muscle to soleus muscle that had undergone either 0.5, 1, 2, 4, 7, 10 and 14 days of hindlimb suspension-induced atrophy or hindlimb suspension-induced atrophied soleus muscle that had undergone 1 hour, 8 hour, 1 day, 2 day, 4 day and 7 days of reweighting-induced hypertrophy. Muscle mass measurements demonstrated continual loss of soleus mass occurred throughout the 21 days of hindlimb suspension; following reweighting, atrophied soleus muscle mass increased dramatically between 8 hours and 1 day post reweighting. Proteomic analysis of normal and atrophied soleus muscle demonstrated statistically significant changes in the relative levels of 29 soleus proteins. Reweighting following atrophy demonstrated statistically significant changes in the relative levels of 15 soleus proteins. Protein identification using mass spectrometry was attempted for all differentially regulated proteins from both atrophied and hypertrophied soleus muscle. Five differentially regulated proteins from the hindlimb suspended atrophied soleus muscle were identified while five proteins were identified in the reweighting-induced hypertrophied soleus muscles. The identified proteins could be generally grouped together as metabolic proteins, chaperone proteins and contractile apparatus proteins. Together these data demonstrate that coordinated temporally regulated changes in the skeletal muscle proteome occur during disuse-induced soleus muscle atrophy and reweighting hypertrophy.

Amino Acid Sequence↗
PubMed2005

Study of interaction between ibuprofen and nicotinamide using differential scanning calorimetry, spectroscopy, and microscopy and formulation of a fast-acting and possibly better ibuprofen suspension for osteoarthritis patients.

Solid-state interaction between ibuprofen and nicotinamide was studied using thermal, spectroscopic, and microscopic techniques. Solubility enhancement was calculated by high-performance liquid chromatography and suspension was found to be the suitable choice of formulation. Ibuprofen-nicotinamide binary mixtures were prepared by solvent evaporation method. Differential scanning calorimetry was used to investigate the stoichiometry and thermal properties of the complex between ibuprofen and nicotinamide. A sharp, single endotherm was observed between the melting endotherms of the individual components at a composition of 60% ibuprofen and 40% nicotinamide (w/w). Several spectroscopic techniques such as ultraviolet-visible, Fourier transform infrared, nuclear magnetic resonance, and powder X-ray diffraction were used to investigate the type of interaction between the two components. Optical microscopy was performed to observe changes with regard to particle size and crystal habit. It was concluded that the interaction that occurred was Pi donor-Pi acceptor in nature and too weak to sustain the integrity of the complex in the liquid state. The solubility of ibuprofen was enhanced by 62 times in the suspension when the concentration of nicotinamide was 13.3 mg/mL. The suspension prepared in this study has potential of being a better medication for pain relief in patients with osteoarthritis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Factors affecting shear thickening behavior of a concentrated injectable suspension of levodopa.

Previous clinical studies on a subcutaneous injectable suspension of levodopa showed poor injectability into human tissue. When this formulation was rheologically characterised, a clinical shear thickening interval was observed at increased shear rates. The formulation parameters that contributed to this rheological behavior were systematically evaluated with the aim of removing this flow limitation while maintaining the concentration of 60% levodopa to retain the clinical applicability. The three suspension parameters examined were: levodopa volume fraction, concentration of the HPMC suspending vehicle, and particle size distribution. Shear thickening increased with the drug concentration and the critical shear rate was inversely dependent on the drug concentration. Increasing the vehicle concentration retarded the shear thickening but increased the overall suspension viscosity. There was an increase in shear thickening with increased average particle diameter. Combinations of micronized and non-micronized particles were used to prepare bimodal particle size distributions. The rheology of these bimodal distributions resulted in removal of shear thickening. This allowed the preparation of 60% levodopa formulations that showed a range of flow characteristics spanning near Newtonian flow or shear thinning at initial injectable viscosities of about 0.6 Pa.s and final viscosities in the range of 0.1 Pa.s, alleviating the shear thickening limitation of these levodopa formulations.

Chemistry, Pharmaceutical↗
PubMed2005

Spectroscopic analysis of highly concentrated suspensions of bovine somatotropin in sesame oil.

Spectroscopy was employed to analyze the structural and thermal stability of highly concentrated oil suspensions of bovine somatotropin (bST). These methods were then compared with more dilute aqueous solutions (1 and 10 mg/mL). All oil suspensions were opaque, viscous, and highly concentrated in bST (>300 mg/mL) and thus provided unique analytical challenges. Using front surface fluorescence and ATR-FTIR spectroscopy, protein structure and stability could be directly monitored in this environment. Differences were detected in structure between concentrated oil and dilute aqueous formulations. Fluorescence spectroscopy found that bST was highly thermally stabile within oil suspensions, since minimal changes in emission peak maxima and emission intensity were observed with increasing temperature when compared to dilute solutions. It was also observed that the amount of aggregate in a sample had some effect on the fluorescence spectra. As the amount of aggregated protein increased, the emission peak maximum and emission intensity changed. Employing ATR-FTIR, the secondary structure was examined with increasing temperature. The secondary structure of bST was also found to be very thermally stabile since no change in relative amount of helix/random structure is observed up to 70 degrees C while significant losses are observed in aqueous solution. This study demonstrates that conformational stability can be directly analyzed within highly concentrated, opaque environments using slight modifications of conventional methods.

Animals↗
PubMed1975

Apparent absorption kinetics of micronized griseofulvin after its oral administration on single- and multiple-dose regimens to rats as a corn oil-in-water emulsion and aqueous suspension.

This investigation was designed to quantitate and compare in the rat the oral absorption characteristics of micronized griseofulvin from a corn oil-in-water emulsion dosage form containing suspended drug and a control aqueous suspension after single-dose (50 mg/kg) and multiple-dose (50 mg/kg every 12 hr for five doses) administrations. The time course of intact drug in the plasma of all animals was best described by a one-compartment open model with apparent zero-order absorption. In contrast to that observed with the aqueous suspension, the onset of drug absorption after single-dose administration of the corn oil emulsion was significantly delayed. This difference disappeared upon multiple dosing of the two dosage forms, with the mean onset being quite rapid in both cases. Administration of a single dose of the antibiotic as the corn oil emulsion resulted in considerable increases in the maximum plasma levels of griseofulvin and in the duration, relative extent, and uniformity of drug absorption compared to those observed after administration of the control aqueous suspension. The potentiating effects of the lipid on drug absorption persisted on multiple dosing but at a somewhat reduced level.

Administration, Oral↗
PubMed1976

Filtration rates of pharmaceutical suspension systems.

This study was undertaken to find it a correlation exists between the filtration rate and the Hu/Ho ratio. For this purpose, flocculated and coagulated structures of sulfamerazine were used. Suspension settling profiles and filtration rates, using additives and additive-free sulfamerazine suspensions, were studied. A straight-line correlation was found. Effects of filter bed parameters on refiltration rates were studied, and a relationship was found by the use of the Kozeny-Carman equation. A straight-line relationship existed between the H1/Ho ratio and the filtration rate exhibited by the different suspension aggregates.

Aluminum↗