A comparison of contiguous two-level anterior cervical discectomy and fusion using a structural allograft versus a Polyetheretherketone (PEEK) cage: the results of a three-year follow-up.

BACKGROUND: Allografts and polyetheretherketone (PEEK) cages are the two most commonly used materials in anterior cervical discectomy and fusion (ACDF). However, their effectiveness in two-level ACDF remains controversial. The primary aim of this retrospective study was to compare the clinical and radiological outcomes of two-level ACDF with plate fixation using either a structural allograft or a PEEK cage. METHODS: From 2010 to 2015, 88 consecutive patients underwent two-level ACDF, of whom 53 received an allograft and 35 patients received a PEEK cage. All PEEK cages were filled with local autografts. All clinical outcomes were prospectively collected before and six months and two years after surgery. Clinical efficacy was evaluated using a visual analogue scale for neck pain and limb pain, the Neck Pain and Disability Score, the Neck Disability Index, the Neurogenic Symptom Score, and the Japanese Orthopedic Association score. Radiological outcomes were assessed preoperatively, immediately after surgery, and at the final follow-up. RESULTS: A preoperative comparison revealed no difference between the two patient groups in terms of age, sex, body mass index, smoking status, preoperative symptoms, operation level, or follow-up (mean = 42.8 months). No differences in the improvements in clinical outcomes were observed between the two groups. Both groups showed significant improvement in mean disc height, segmental height, and segmental lordosis postoperatively. The fusion rate for the PEEK cage was 100% at both levels, while the fusion rate for the allograft group was 98.1% at the cephalad level and 94.2% at the caudad level (p > 0.05). Subsidence at the cephalad level occurred in 22.9% (8/35) of segments in the PEEK group and 7.7% (4/52) of segments in the allograft group (p = 0.057). At the caudal level, a higher incidence of cage subsidence was noted in the PEEK group than in the allograft group [37.1% (13/35) versus 15.4% (8/52)] (p = 0.02). Overall, subsidence was noted in 30% (21/70) of the PEEK group and in 11% (12/104) of the allograft group (p <  0.05). CONCLUSION: The use of PEEK cages resulted in a higher rate of subsidence in two-level ACDF than the use of allografts. Two-level ACDF using either allografts or PEEK cages resulted in similar clinical outcomes, radiological improvements in alignment and fusion rates.

The risk of bacteria in foam sclerotherapy: does the condition of the air in outpatient vs. operating rooms make a difference?

BACKGROUND: Foam sclerotherapy has been one of the most frequently applied therapeutic methods for the treatment of varicose veins and venous malformation. Few studies have investigated the sterile condition of the air used for foam creation. OBJECTIVES: To evaluate the bacterial conditions in foam created from the air in outpatient and operating rooms used for sclerotherapy treatment, in order to provide the basis for clinical applications in foam sclerotherapy. MATERIALS AND METHODS: In this study, we measured the amount of airborne microorganisms in the air in the operating room, and in the outpatient room, the polidocanol (POL) foam created using the air in the respective rooms, and the microorganisms present in the liquid POL. We used the settle plate method for air sampling. We used the Tessari method to generate foam. The experiment was repeated three times. RESULTS: Typical bacterial colonies were formed on nutrient agar plates in both the outpatient room and operating room air groups. No colonies were cultivated in the liquid POL. Although the use of sterile or nonsterile air in sclerotherapy produces significantly different results in the counts of colony-forming units, there was no difference in the foam created using sterile or nonsterile air (i.e. no colonies were cultivated on either foam). CONCLUSIONS: There is no increased risk of infection when using foam sclerotherapy in outpatient rooms compared with using foam created under sterile operating-room conditions.

Polyetheretherketone interbody cages versus autogenous iliac crest bone grafts with anterior fixation for cervical disc disease.

OBJECTIVE: The aim of this study was to compare the fusion rate, operation time, recovery of disc space height, clinical duration and improvement, return to activities of daily living, and complication rate associated with anterior cervical discectomy with interbody fusion by using polyetheretherketone cages or autogenous iliac crest bone grafts as disc replacement in a series of 60 patients. MATERIALS AND METHODS: Between November 2006 and February 2010 a retrospective analytical observational cohort study was carried out in 60 consecutive patients surgically treated with anterior cervical discectomy with interbody fusion for degenerative disc desease at the Neurosurgical Department of the Hospital Italiano de Buenos Aires. The patients were divided into 2 groups for the assessment of clinical characteristics, demographics, fusion rates, duration of surgical procedure, neurological and functional outcomes, imaging results, and complications. Group A included patients treated with autogenous iliac crest bone grafts, and group B included patients treated with polyetheretherketone cages. RESULTS: The mean age of the patients was 50.8 years. Female patients comprised the majority in both groups (63.3%). Cervicobrachialgia was the most common presentation. Clinical improvement, fusion rates, and recovery of disc space height were similar in both groups. The operation time was significantly shorter in the polyetheretherketone group (P<0.001). Twenty percent (n=6) of the patients in group A suffered complications, >80% of which were associated with iliac crest bone graft harvesting. Patients in group B had no complications (P<0.05). CONCLUSIONS: Although outcomes were very successful in both groups in terms of fixation stability, recovery of disc space, return to activities of daily living and work, and remission of symptoms, operation time was considerably shorter for patients in the polyetheretherketone group, who had none of the complications associated with iliac crest bone graft harvesting, both differences being statistically significant.

Absence of concentration congruity in six compounded polidocanol samples obtained for leg sclerotherapy.

BACKGROUND: In the arena of venous sclerotherapy, sodium tetradecyl sulfate (STS), hypertonic saline, and polidocanol (POL) are the most widely used agents in the world for treating endothelial vein wall destruction. Pharmaceutical-grade STS and hypertonic saline are available from manufacturers. Until 2010, POL was only available in the United States through compounding pharmacies. OBJECTIVE: To identify whether a risk exists when using freely available compounded POL samples for venous sclerotherapy. MATERIALS AND METHODS: Six samples of 1% POL solutions obtained from four compounding pharmacies were evaluated using gas chromatography mass spectrometry (GC/MS) assays for POL concentration and identification of material impurities. RESULTS: Disparities in POL concentrations between six samples ranged from 1.0% to 3.1%. The GC/MS analysis showed impurities in all six compounded POL samples. CONCLUSIONS: In this study, compounded POL solutions did not deliver the claimed concentration five out of six times. This inconsistency poses risks to the patient and the treating physician during venous sclerotherapy with pharmacy-compounded POL. Merz Aesthetics provided funding for this study.

Bioavailability study of berberine and the enhancing effects of TPGS on intestinal absorption in rats.

Berberine chloride (BBR) is a natural isoquinoline alkaloid extracted from medicinal herbs. It has been reported that the intestinal absorption of BBR is very low. In this study, the absolute bioavailability of BBR was studied, and the enhancing effects of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) on intestinal absorption were investigated in rats. BBR injection was administrated via the femoral vein at a dose of 1.0 mg kg(-1) in intravenous group, and BBR oral formulations were administrated by oral gavage at a dose of 100 mg kg(-1) in BBR control (control) group and BBR-TPGS (test) group, respectively. The result showed that BBR had a very low absolute bioavailability of 0.68%, and TPGS could enhance intestinal absorption of BBR significantly. TPGS at a concentration of 2.5% could improve peak concentration (C(max)) and area under the curve (AUC(0-36)) of BBR by 2.9 and 1.9 times, respectively. The absorption enhancing ability of TPGS may be due to its ability to affect the biological activity of P-glycoprotein and thereby reduce the excretion of absorbed BBR into the intestinal lumen. This study indicated that absolute bioavailability of BBR was 0.68% in rats, and TPGS was a good absorption enhancer capable of enhancing intestinal absorption of BBR significantly.

Load Sharing and Endplate Pressure Distribution in Anterior Interbody Fusion Influenced by Graft Choice.

BACKGROUND: Cage subsidence is a known complication of spinal fusion. Various aspects of cage design have been investigated for their influence on cage subsidence, whereas the potential contribution of graft material to load sharing is often overlooked. We aimed to determine whether graft in the aperture affects endplate pressure distribution. METHODS: The pressure distributions of a polyetheretherketone interbody cage with 3 different aperture graft conditions were evaluated: empty, demineralized bone matrix, and supercritical CO2-treated allograft bone crunch (SCCO2). RESULTS: Graft materials contributed as much as half the load transmission for SCCO2, whereas demineralized bone matrix contributed one third. Endplate areas in contact with the cage demonstrated decreased areas within the highest-pressure spectrum with SCCO2 graft materials compared with empty cages. CONCLUSIONS: Graft choice plays a role in reducing peak endplate pressures. This finding is relevant to implant subsidence, as well as graft loading and remodeling.

Outcomes of interbody fusion cages used in 1 and 2-levels anterior cervical discectomy and fusion: titanium cages versus polyetheretherketone (PEEK) cages.

STUDY DESIGN: A prospective study was performed in case with cervical spondylosis who underwent anterior cervical discectomy and fusion (ACDF) with titanium or polyetheretherketone (PEEK) cages. OBJECTIVE: To find out which fusion cage yielded better clinical and radiographic results. SUMMARY OF BACKGROUND DATA: Although use of autogenous iliac-bone grafts in ACDF for cervical disc diseases remain standard surgical procedure, donor site morbidity and graft collapse or breakage are concerns. Cage technology was developed to prevent these complications. However, there is no comparison regarding the efficacy between titanium and PEEK cage. METHODS: January 2005 to January 2006, 53 patients who had 1 and 2-levels ACDF with titanium or PEEK cages were evaluated. We measured the rate and amount of interspace collapse, segmental sagittal angulations, and the radiographic fusion success rate. Odom criteria were used to assess the clinical results. RESULTS: The fusion rate was higher in the PEEK group (100% vs. 86.5%, P=0.0335). There was no significant difference between both groups in loss of cervical lordosis (3.2 + or - 2.4 vs. 2.8 + or - 3.4, P=0.166). The mean anterior interspace collapse (1.6 + or - 1.0 mm) in the titanium group was significantly higher than the collapse of the PEEK group (0.5 + or - 0.6 mm) (P<0.0001). The mean posterior interspace collapse was also higher in the titanium group (1.6 + or - 0.9 mm vs. 0.5 + or - 0.5 mm, P<0.0001). An interspace collapse of 3 mm or greater was observed in 16.2% of the patients in the titanium group, compared with zero patients in the PEEK group (P<0.0001). The PEEK group achieved an 80% rate of successful clinical outcomes, compared with 75% in the titanium group (P=0.6642). CONCLUSIONS: The PEEK cage is superior to the titanium cage in maintaining cervical interspace height and radiographic fusion after 1 and 2-levels anterior cervical decompression procedures.

Surgical preference regarding different materials for custom-made allograft cranioplasty in patients with calvarial defects: Results from an internal audit covering the last 20 years.

BACKGROUND: Secondary cranioplasty (CP) plays a key role in restoring cranial vault anatomy and normal brain function following decompressive craniectomy (DC). The scientific literature provides only fragmentary information regarding the best timing and material for CP, making a direct comparison of different materials difficult. OBJECT: To identify and report according to STROBE guidelines local trends in choice of materials for CP, complications rate and surgical outcomes. METHODS: We conducted an audit on secondary CP covering the last 20 years of surgical practice at our Institution. Custom-made CP used over the years were made of: porous hydroxyapatite (PHA), polymetylmethacrylate (PMMA), polyetheretherketone (PEEK), acrylic and titanium. The primary endpoint of this study was the incidence of postoperative complications, such as: implant infection, fracture and dislocation. Secondary endpoints were the followings: patients satisfaction with cosmetic result, rate of implant integration, and long-term neurological outcome. RESULTS: A total of 218 patients were included, given the predominance of PHA (Group A) or PMMA (Group B) CP, a direct comparison was made only between those two groups. Overall reoperation rate was 6.5% versus 28%; implants' osseointegration rate was of 69% versus 24%; satisfaction rate was 66% versus 44%, in Group A and B respectively. CONCLUSIONS: This single-centre study provides Level 3 evidence that PHA yields better outcomes than PMMA CP. Designing a management algorithm for planning and executing CP is difficult for clinical and organizational reasons; till a widespread consensus is reached, neurosurgeons with subspecialty interest in neurotrauma should favor pragmatism and patient safety over costs.

Use of a Predictive Regression Model for Estimating Hold-Up Volume for Biologic Drug Product Presentations.

A drug delivery system is designed to administer a therapeutic dose according to its label claim. Upon delivery of a parenteral drug product, the volume remaining inside the container that cannot be extracted at the end of drug administration is called the hold-up volume (HUV) and is primarily considered product wastage. To meet the label claim, every drug product container is filled with a slight excess volume. For early-stage products in clinical phase, for which material availability is often a limitation, excess volume in drug product containers has to be determined experimentally using several grams of product. In such scenarios, established models that can predict HUV in primary drug product containers would be valuable for product development. The objective of this study was to determine HUV with 95% confidence intervals across various container closures and drug delivery systems by using aqueous PEG 400 solution mimicking the viscosity of biologic drug products. ISO 2R, 6R, and 10R vials and single-use hypodermic syringes attached to a Luer lock needle (25 gauge, 1½ in.) were used to mimic parenteral drug product container and delivery systems for determination of HUV. Glass prefilled syringes in 1 mL and 2.25 mL configurations were also used to determine HUV with 95% confidence intervals. A linear regression model was developed for determination of HUV as a function of viscosity and as a function of container closure and a needle-based delivery system. This model predicting HUV was confirmed by using monoclonal antibodies of varying formulations and viscosities for container closure and delivery systems tested in this study. The model provided here can be used to determine HUV for a particular container closure for a drug solution with known viscosity that can subsequently be used to evaluate fill volume specifications and label claim for a dosage form.

[Observation of stand-alone MC+polyether-ether-ketone (PEEK) Cage in anterior cervical double-level fusion for more than 2 years follow-up].

OBJECTIVE: To investigate the effectiveness of stand-alone MC+polyether-ether-ketone (PEEK) Cage (single blade type) in anterior cervical double-level fusion for more than 2 years follow-up. METHODS: A clinical data of 30 patients who were treated with anterior cervical fusion surgery with stand-alone MC+PEEK Cage (single blade type) between January 2013 and December 2016 and followed up for more than 2 years, was retrospectively analyzed. There were 16 males and 14 females, aged from 34 to 72 years with an average of 52.2 years. There were 16 cases of cervical spondylotic myelopathy, 8 cases of cervical spondylotic myelopathy, and 6 cases of traumatic cervical disc herniation. The continuous double segments were C 4, 5, C 5, 6 in 12 cases and C 5, 6, C 6, 7 in 18 cases; and the disease duration ranged from3 days to 24 months (mean, 12 months). Postoperative neck hematoma and wound healing were observed; dysphagia was assessed by Bazaz system; and bone fusion was assessed by Suk method. Before operation, at 1 week after operation, and at last follow-up, the Japanese Orthopaedic Association (JOA) score was used to evaluate the neurological recovery; the cervical X-ray film was performed to record the cervical curvature (C 2-C 7 Cobb angle), the height of the intervertebral space of the fusion segment, and to judge the occurrence of the fusion Cage subsidence. RESULTS: No complication such as neck hematoma, incision infection, or esophageal fistula was found, primary healing of incisions was obtained in all cases. All patients were followed up 24-72 months (mean, 46 months). Neurological symptoms such as limb numbness and pain gradually disappeared after operation; during the follow-up period, the cervical curvature could be effectively maintained; dysphagia and internal fixation related complications such as displacement of Cages were not found. All patients obtained bony fusion from 3 to 8 months with an average time of 4.3 months. Compared with preoperative ones, the JOA score, intervertebral space height, and Cobb angle of cervical spine were significantly improved at 1 week after operation and at last follow-up ( P<0.05), but there was no significant difference between 1 week after operation and last follow-up ( P>0.05). CONCLUSION: The application of stand-alone MC+PEEK Cage (single card type) in anterior cervical fusion can provide early cervical stability, effectively maintain the physiological curvature of cervical spine and the height of fusion intervertebral space.

Certification and uncertainty evaluation of the certified reference materials of poly(ethylene glycol) for molecular mass fractions by using supercritical fluid chromatography.

Poly(ethylene glycol) (PEG) is a useful water-soluble polymer that has attracted considerable interest in medical and biological science applications as well as in polymer physics. Through the use of a well-calibrated evaporative light-scattering detector coupled with high performance supercritical fluid chromatography, we are able to determine exactly not only the average mass but also all of the molecular mass fractions of PEG samples needed for certified reference materials issued by the National Metrology Institute of Japan. In addition, experimental uncertainty was determined in accordance with the Guide to the expression of uncertainty in measurement (GUM). This reference material can be used to calibrate measuring instruments, to control measurement precision, and to confirm the validity of measurement methods when determining molecular mass distributions and average molecular masses. Especially, it is suitable for calibration against both masses and intensities for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Development of a Flow-Through USP-4 Apparatus Drug Release Assay to Evaluate Doxorubicin Liposomes.

Doxil® is a complex parenteral doxorubicin (DOX) liposome formulation approved by the FDA. For generic doxorubicin liposomes, analyzing the release profile of DOX is important for quality control and comparability studies. However, there is no robust standard drug release assay available for doxorubicin liposomes. In this study, we describe a USP-4 apparatus assay capable of discriminating DOX liposomal formulations based on release profile. Establishment of the assay was hindered by limited DOX release from liposomes in physiological conditions at 37°C. The addition of NH4HCO3 to the release media facilitated DOX release proportionally to the salt concentration added but caused precipitation of released drug in USP-4 apparatus. Precipitation of DOX was avoided by adding hydroxypropyl-cyclodextrin (HP-CD) to the release medium. We optimized conditions for DOX release by varying a number of parameters such as: concentration of HP-CD, testing temperature, and concentration of tested samples. The optimized release medium contained: 100 mM NH4HCO3, 75 mM 2-(N-morpholino) ethanesulfonic acid (MES) and 5% w/v HP-CD, 5% w/v sucrose, 0.02% w/v NaN3 (pH 6). The drug release assay was performed at 45°C. The optimized release assay can discriminate between DOX liposomal formulations of different compositions, physicochemical properties, and prepared by different manufacturing methods. This indicates that the assay could be used to compare DOX release from generic DOX formulations to the innovator product Doxil®.

Comparison of allograft and polyetheretherketone (PEEK) cage subsidence rates in anterior cervical discectomy and fusion (ACDF).

Structural allografts and PEEK cages are commonly used interbody fusion devices in ACDF. The subsidence rates of these two spacers have not yet been directly compared. The primary aim of this study was to compare the subsidence rate of allograft and PEEK cage in ACDF. The secondary aim was to determine if the presence of subsidence affects the clinical outcome. We reviewed 67 cases (117 levels) of ACDF with either structural allograft or PEEK cages. There were 85 levels (48 cases) with PEEK and 32 levels (19 cases) with allograft spacers. Anterior and posterior disc heights at each operative level were measured at immediate and 6months post-op. Subsidence was defined as a decrease in anterior or posterior disc heights >2mm. NDI of the subsidence (SG) and non-subsidence group (NSG) were recorded. Chi-square test was used to analyze subsidence rates. T-test was used to analyze clinical outcomes (α=0.05). There was no statistically significant difference between subsidence rates of the PEEK (29%; 25/85) and allograft group (28%; 9/32) (p=0.69). Overall mean subsidence was 2.3±1.7mm anteriorly and 2.6±1.2mm posteriorly. Mean NDI improvement was 11.7 (from 47.1 to 35.4; average follow-up: 12mos) for the SG and 14.0 (from 45.8 to 31.8; average follow-up: 13mos) for the NSG (p=0.74). Subsidence rate does not seem to be affected by the use of either PEEK or allograft as spacers in ACDF. Furthermore, subsidence alone does not seem to be predictive of clinical outcomes of ACDF.

Pharmacometric Modeling of Naloxegol Efficacy and Safety: Impact on Dose and Label.

Naloxegol is a peripherally acting µ-opioid receptor antagonist that was developed for the treatment of opioid-induced constipation. Modeling and simulation of naloxegol efficacy and tolerability informed selection of doses for phase III studies and provided comprehensive dosage recommendations for the naloxegol US package insert.

Cross-linked hydrogels for middle ear packing.

OBJECTIVE: To develop an ideal supportive packing material for ossiculoplasty, tympanoplasty, or other otologic procedures. MATERIALS AND METHODS: Several materials, namely, Carbylan-SX (P-C; Sentrx Surgical, Inc., Salt Lake City, UT), Gelfoam (P-GF; Pharmacia & Upjohn, Kalamazoo, MI), and Merogel (P-MG; Medtronics, Inc., Minneapolis, MN), were prepared and then placed into a Hartley guinea pig's (Elm Hill, Chelmsford, MA) middle ear cavities through a large myringotomy incision. The contralateral ear underwent a large myringotomy without packing material being placed. Preoperative and posteroperative auditory brainstem response studies were performed using Intelligent Hearing system software. The animals were examined weekly. Two weeks after packing placement, the animals were killed, and the temporal bones were harvested. Whole temporal bone sectioning was performed to analyze the presence of implant, surrounding inflammation, presence of osteoneogenesis and fibrosis, or adhesions. RESULTS: All the materials, except the P-MG, were easy to place into the middle ear cavity. The P-MG contains woven strands that are difficult to trim into the small sizes needed for placement. The P-MG group had a smaller average amount of implant present compared with the other groups at 2 weeks. The degree of osteoneogenesis was similar among the P-GF, P-C, and P-MG groups. The P-MG and P-C groups contained the lowest amount of fibrosis between the implant and surrounding middle ear structures. CONCLUSION: This study demonstrates promising results with P-C as a potential supportive packing material for otologic procedures. P-C compares favorably with P-MG and P-GF in a guinea pig model with respect to ease of placement and amount of fibrosis.

Tamper-proof tablets for distinction between counterfeit and originator drugs through PEG coding.

Counterfeit drugs are a major threat to public health. Current efforts focus on serialization of the secondary packaging which do not allow to trace the individual unit. As a proof of concept, we intended to mark each tablet for its unambiguous recognition. Spiking monodisperse PEGs into tablet coating solutions at concentrations as low as 3 ppm was instrumental to "write" a code into each tablet film which was readily read upon isolation and LC-MS/MS analysis. Different qualities and amounts of monodisperse polyethylene glycols can be used for coding solid drug products. The approach is limited to cases in which PEGs are not present for formulation purposes as excipients, as coding against this background was unfeasible.

High resolution particle characterization to expedite development and regulatory acceptance of nanomedicines.

The pharmaceutical industry as well as European and US governing agencies have indicated the need for more accurate, high resolution, characterization of complex drug materials, nanomedicines, to facilitate their development and eventual approval. In particular, accurately measuring the size, zeta-potential, and concentration of nanomedicines is desired. Herein we demonstrate the comprehensive and high resolution analysis capabilities of tunable resistive pulse sensing (TRPS) on the most widely approved nanomedicines to-date, liposomal particles. The number-based size distribution, concentration and volume fraction of liposomes formed by extrusion through a 100 nm or 200 nm Nucleopore filter membrane are shown as well as how freeze-thaw aggregation changes individual liposomes and the overall size distribution. In addition, the simultaneous size and zeta-potential analysis capabilities of TRPS is used to characterize the homogeneity and difference between liposomes made with and without the addition of PEGylated phospholipids.

Influence of filler parameters on the mechanical coherence of dental restorative resin composites.

Next to the presence of (chemical) coupling between filler and resin, filler particle size is important for the mechanical coherence of dental resin composites which are used for posterior restorations. In the range of the current composites a smaller particle size is desirable. The better mechanical coherence for composites with smaller particles found in an in vitro erosive wear test is probably related to the size of food fibres, which are part of the erosive medium. It appears that there is a critical value of the filler particle size (1.3-1.5 microns), under which the food fibres are not able to penetrate in the interparticle space, so the erosive capability of the erosive medium will be reduced.

Usefulness of polyethylene glycol for cryopreservation by vitrification of in vitro-derived bovine blastocysts.

A series of five experiments measured the high survival of bovine blastocysts produced in vitro after cryopreservation by vitrification. The vitrification solution (designated VS) contained 40% (v/v) ethylene glycol, 6% (w/v) polyethylene glycol and 0.5 M sucrose in phosphate-buffered saline. Embryos developed in vitro at Days 7 and 8 (Day 0 = insemination day) were exposed in one step to VS for 1 min or two steps with 10% ethylene glycol for 5 min and then VS for 1 min. In both cases, the embryos were finally cryopreserved in liquid nitrogen. After the embryos were warmed rapidly and the VS solution diluted, the survival rates were assessed by monitoring hatching rate in vitro. They were 13.0% for the one-step and 72.7% for the two-step procedures (P < 0.001). When embryos were exposed to individual solutions containing 6% (w/v) of each of 4 macromolecules (polyethylene glycol, BSA, polyvinylpyrrolidone or Ficoll) in the two-step protocol and then cryopreserved, the survival rates were 79.3, 34.8, 41.4 and 57.1%, respectively. After embryos had been exposed to the VS in two steps and then cryopreserved, there were no significant differences in survival rates when the solutions were diluted with or without sucrose. These results indicated that a vitrification solution containing polyethylene glycol can be used for cryopreservation of bovine blastocysts produced in vitro, and that a two-step addition of VS improved the in vitro survival of post-warming embryos. It was also shown to be possible to dilute post-warming embryos directly without the use of sucrose solution.

In vitro investigations of a new hydrogel dressing.

The aim of this study was to investigate in vitro the fluid-handling properties of a new hydrogel dressing (Aquaform) and to compare these with the fluid-handling properties of a commonly used hydrogel dressing (Intrasite Gel). The results of laboratory tests indicate that the new hydrogel can absorb substantial amounts of fluid from simulated wet wounds and donate substantial amounts of fluid to simulated dry or necrotic wounds. The amount of fluid exchanged in both wound types for the new hydrogel was similar to that for Intrasite Gel.