Polyvinyl Alcohol Group Research Articles

Dissipative Particle Dynamics Simulations on Mesoscopic Structures of Nafion and PVA/Nafion Blend Membranes

Dissipative particle dynamics simulations were performed to study the mesoscopic structures of both humidified Nafion and polyvinyl alcohol(PVA)/Nafion blend membranes.Simulation results show that a phase-segregated microstructure is formed in both humidified Nafion and PVA/Nafion blend membranes.In humidified Nafion membrane,water molecules and sulfonate groups form tubular shaped water clusters.As the water content is increased,the size of water cluster is enlarged and water clusters percolate to form a continuous water channel.In the PVA/Nafion blend membrane,PVA,water molecules, and sulfonate groups together form hydrophilic domains.The mesoscopic structure of the PVA/Nafion blend membrane is affected by both the PVA/Nafion blend ratio and the water content in the membrane. When the PVA mass fraction is relatively low,PVA is predominantly distributed along the sulfonate groups of Nafion and as the PVA mass fraction is increased,PVA alone forms a distinct phase in the membrane. When the water content in the membrane is relatively low,water molecules are predominantly dissolved in PVA and as the water content is increased,spherical water clusters emerge in the membrane.This work provides further guidance for the development of PVA modified Nafion membranes for direct methanol fuel cell applications.

Long-term outcome of angiographic partial splenectomy in patients with decompensated liver cirrhosis and hypersplenism

Background and study aims Hypersplenism is one of the serious complications of splenomegaly complicating liver cirrhosis. Although partial splenic embolization has been proposed in patients with cirrhosis and thrombocytopenia, there are limited data on long-term outcome. The aim of our study was prospective evaluation of the long-term effects of angiographic partial splenectomy (APS) using polyvinyl alcohol (PVA) or gelfoam particles in patients with decompensated liver cirrhosis and hypersplenism. Patients and methods This study was done at Radiology and Tropical Medicine of Tanta University hospitals. Sixty patients were randomly assigned to two equal groups, PVA group, and gelfoam group. Control group included 18 patients, who refused invasive procedures and treated conservatively. Informed consent was obtained from every patient. Results All groups were matched as regards age, sex, Child class, presence of oesophageal varices and complete blood count findings. APS was successfully performed in all 60 patients. Post-embolization syndrome was the most frequent side effect in both test groups while the need for repeated transfusions was significantly higher in the control group. No significant difference in mortality for all groups was detected. Variceal bleeding was significantly more in the control group. The procedure related complications were comparable in both test groups. All blood indices have significantly improved in comparison to the control group ( p < 0.05). In both test groups white blood cells (WBCs), platelets (PLT) and haemoglobin improved significantly in comparison to the pre-procedure values ( p < 0.05). Post-procedure WBCs and PLT were significantly higher in the gelfoam group than those in the PVA group ( p < 0.05). Conclusion APS is effective and has a favourable long-term outcome in the treatment of hypersplenism in Egyptian patients with decompensated post-hepatitis C cirrhosis. APS decreased the need for repeated transfusions. Both types of embolizing particles (PVA and gelfoam) were comparable as regards efficacy and post-procedure complications. APS may decrease the rate of variceal bleeding and future studies are needed to clarify its effects on portal hypertension.

Synthesis and evaluation of a hydrogel that binds glucose and releases ciprofloxacin

This study reports the formation of a hydrogel generated by polymerizing aminophenyl boronic acid in polyvinyl alcohol (PVA). The gel formed as a result of complexation between the –OH groups of PVA, and boronic acid moieties were stable and exhibited high degree of swelling proportional to the concentration of glucose. Extended swelling was attributed to the strong affinity of the gel to glucose and to the subsequent breaking of the bond formed between PVA and boronic acid groups. Interestingly, the gel was found to bind a high amount of glucose. We evaluated the hydrogel in terms of its ability to bind glucose and to release ciprofloxacin. Retention of antibacterial efficacy of the released drug was also demonstrated. Features such as swelling, drug release, and glucose binding reflect the possibility of tuning a new dressing for wounds particularly in diabetic patients.

Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk nanocomposites thin film

Iron oxide (α-phase) nanoparticles with coercivity larger than 300 Oe have been fabricated at a mild temperature by an environmentally benign method. The economic sodium chloride has been found to effectively serve as a solid spacer to disperse the iron precursor and to prevent the nanoparticles from agglomeration. Higher ratios of sodium chloride to iron nitrate result in smaller nanoparticles (19 nm for 20:1 and 14 nm for 50:1). The presence of polyvinyl alcohol (PVA) limits the particle growth (15 nm for 20:1 and 13 nm for 50:1) and favors nanoparticle dispersion in polymer matrices. Obvious physicochemical property changes have been observed with PVA attached to the nanoparticle surface. With PVA attached to the nanoparticle surface, the nanoparticles are found not only to increase the PVA cross-linking with an increase in melting temperature but also to enhance the thermal stability of the PVA. The nanoparticles are observed to be uniformly dispersed in the polymer matrix. Scanning electron microscopy (SEM) microstructure also shows an intermediate phase with a strong interaction between the nanoparticles and the polymer matrices, arising from the hydrogen bonding between the PVA and hydroxyl groups on the nanoparticle surface. The addition of nanoparticles favors the cross-linkage of the bulk PVA matrices, resulting in a higher melting temperature, and an enhanced thermal stability of the polymer matrix.

Preimplantation development and expression of Hsp-70 and Bax genes in bovine blastocysts derived from oocytes matured in alpha-MEM supplemented with growth factors and synthetic macromolecules

In vitro culture conditions affect both the maternal and embryonic expression of genes and is likely to alter both oocyte and embryo developmental competence. The search for better and less variable culture conditions simulating those in vivo has led to the development of defined culture media, with lower impact on the molecular reprogramming of oocytes and embryos. We evaluated embryo development and relative abundance (RA) of Hsp-70 and Bax transcripts in bovine blastocysts produced from oocytes matured in a chemically defined IVM system with synthetic polymers. Immature cumulus oocyte complexes (COCs) were matured for 22–24 h in alpha-MEM supplemented with IGF-1, insulin, 0.1% polyvinyl alcohol (PVA), or 0.1% polyvinylpyrrolidone (PVP), but without FSH or LH. The control group consisted of COCs matured in TCM plus FSH and 10% estrous cow serum. After fertilization, presumptive zygotes were co-cultured with cumulus cells until 224 h post-insemination. Total RNA was isolated from embryo pools, reverse transcribed into cDNA, and subjected to transcript analysis by real-time PCR. Cleavage rate was higher ( P < 0.05) for the control group (68.3%) than for the PVA (54.4%) and PVP-40 (58.3%) groups. Nevertheless, there was no difference among the PVA, PVP-40 and control groups in blastocyst or hatching rates. Similarly, no difference in relative abundance of Hsp-70 and Bax transcripts was detected in comparison to the control group. We inferred that bovine oocytes can be matured in serum- and gonadotrophin-free medium supplemented with PVA or PVP, enriched with IGF-I and insulin, without altering post-cleavage development and relative abundance of some genes associated with stress and apoptosis.

Effect of Catheter-Directed Arterial Embolization and Laparoscopic Endovascular Stapling on Stapled Vessel Integrity in a Porcine Model

Arterial embolization is a frequently performed adjunctive maneuver prior to laparoscopic splenectomy or nephrectomy to facilitate laparoscopic dissection and reduce intraoperative bleeding. However, little is known regarding the effect of laparoscopic stapling across thrombosed vessels with imbedded embolic materials. This study analyzed the stapled line integrity by comparing visceral arteries treated with either platinum coils or polyvinyl alcohol (PVA) particles. Using a porcine model, 30 visceral vessels including splenic and renal arteries were treated with either coil or PVA embolization, which was followed by laparoscopic stapling. Vessel integrity and bursting pressure analysis was performed using an in vitro flow circuitry. The mean bursting pressure of the coil and the PVA group was 158 +/- 56 and 350 +/- 34 mm Hg, respectively (p < .001). The lowest bursting pressure in the coil and the PVA group was 70 and 280 mm Hg, respectively. The highest bursting pressure in the coil and the PVA group was 225 and 420 mm Hg, respectively. The bursting pressure in the splenic artery between the PVA and the coil group was 345 +/- 29 and 150 +/- 54 mm Hg, respectively (p < .001). Significant difference in the bursting pressure in the renal artery was noted in the PVA and the coil group, which was 350 +/- 40 and 160 +/- 40 mm Hg, respectively (p < .001). Our findings showed that preoperative coil embolization followed by laparoscopic vessel stapling sustained a poor busting pressure. Such a practice appears to be unsafe based on our findings and should be performed with caution in a clinical setting.

Partial splenic embolization using polyvinyl alcohol particles for hypersplenism in cirrhosis: A prospective randomized study

Purpose To prospectively evaluate the efficacy and safety of partial splenic embolization (PSE) using polyvinyl alcohol (PVA) particles for hypersplenism in cirrhosis, as compared to PSE using gelfoam particles. Materials and methods PSE was performed in 60 consecutive patients with hypersplenism caused by cirrhosis. The patients were randomly assigned into 2 groups: gelfoam group, 32 patients received PSE using gelfoam particles as the embolic material; PVA group, 28 patients received PSE using PVA particles. The follow-up contents included peripheral blood cell counts (leukocyte, platelet and red blood cell) and complications associated with PSE. Results Prior to PSE, there was no significant difference between the two groups in sex, age, Child-Pugh grade, the extent of embolization and peripheral blood cell counts. After PSE, no matter in which group, leukocyte and platelet counts kept significantly higher than pre-PSE during the 3-year follow-up period ( P < .0001), but the post-PSE improvement of leukocyte and platelet counts was significantly better in PVA group than in gelfoam group ( P < .05). Red blood cell counts showed no remarkable changes after PSE ( P > .05). Severe complications occurred in 8 patients (25.0%) in gelfoam group and 6 patients (21.4%) in PVA group ( P > .05), but the degree of abdominal pain was higher in the latter than in the former ( P < .05). Among 17 patients who received more than 70% embolization of spleen, 10 (58.8%) developed severe complications, while among 43 patients who received 70% or less embolization of spleen, only four (9.3%) had severe complications. This difference was statistically significant ( P < .05). Conclusion PVA particles could be used as the embolic material in PSE; in comparison with PSE using gelfoam particles, PSE using PVA particles can achieve even better efficacy in alleviating hypersplenism, but the extent of embolization should be strictly limited to not more than 70% of splenic volume.

83 DEVELOPMENT OF BOVINE IN VITRO-PRODUCED BLASTOCYSTS AFTER CRYOPRESERVATION IN CHEMICALLY DEFINED SOLUTIONS AND ONE-STEP DILUTION

Efficient embryo cryopreservartion using a protein-free defined solution would be beneficial for hygienic commercial embryo transport. In addition, one-step rehydration of frozen–thawed embryos could allow direct transfer of cryopreserved embryos after thawing. The objective of this study was to assess the viability in vitro of bovine in vitro-produced (IVP) embryos after freezing and thawing in a base cryoprotective solution [modified synthetic oviduct fluid (mSOF) medium containing 1.8 m ethylene glycol and 0.05 m trehalose] supplemented with various concentrations of polyvinyl alcohol (PVA). The methods used for in vitro embryo production and embryo cryopreservation were modified from those described previously (Murakami et al. 1998 Cryobiology 36, 206–212). Briefly, oocytes collected from cow ovaries were matured, fertilized in vitro for 5 h, and cultured in mSOF containing 0.4% bovine serum albumin (BSA) at 38.5�C in a humidified atmosphere of 5% CO2, 5% O2, and 90% N2 (reduced-O2 atmosphere; Day 0). On Day 3, only cleaved embryos were co-cultured with bovine cumulus cells in mSOF containing 5% fetal bovine serum (FBS) in a humidified atmosphere of 5% CO2 in air. On Day 7, embryos that reached the blastocyst stage were selected and immersed directly into the base cryoprotective solution supplemented with 0.4% BSA (0.4BSA group, the protein-containing control group) or 1.5, 3.0, or 6.0% PVA (1.5PVA, 3PVA, and 6PVA groups, respectively) at room temperature. After exposure to solution, embryo–cryoprotectant solutions were loaded into 0.25-mL plastic straws and cryopreserved by the standard slow freezing method (about 60 to 100 embryos in each group). The frozen straws were placed in air for 10 s, and plunged into a 38.5�C water bath for 10 s; the contents were expelled into a plastic dish. The embryos were then transferred directly to pre-incubated minimum essential medium alpha medium containing 5% FBS and MEM nonessential amino acids solution (mαMEM) for one-step rehydration. These frozen.thawed embryos were washed well and cultured in fresh mαMEM in a reduced-O2 atmosphere for 3 days to examine the developmental potential in vitro. Data were analyzed by ANOVA. The percentage of re-expanded embryos after freezing and thawing was significantly higher (P &lt; 0.05) in 0.4BSA and 1.5PVA groups than in the 3PVA and 6PVA groups (95.4% in 0.4BSA and 90.9% in 1.5PVA v. 73.4% in 3PVA and 57.7% in 6PVA). In addition, there was no significant difference between 0.4BSA and 1.5PVA groups in the percentage of embryos developed into hatched blastocysts (82.0 v. 80.2%), but the percentage decreased with increasing PVA concentration (51.1% in 3PVA and 29.3% in 6PVA, respectively). These results suggest that the biological product BSA added in our standard cryoprotective solution can be replaced with 1.5% PVA to support similar viability of frozen.thawed bovine IVP embryos after one-step dilution. Further studies, including direct transfer of these frozen embryos after thawing, are needed to substantiate these results.

Vascular Endothelial Growth Factor Has Beneficial Effect Independent of Serum Components throughout Oocyte Maturation and Early Embryonic Development in Cattle

In our previous studies, we demonstrated that Vascular Endothelial Growth Factor (VEGF) enhances bovine oocyte maturation and early embryonic development in serum supplemented media. In this experiment, to determine the synergistic effect of VEGF with serum components on early embryonic development in vitro in cattle, 1 mg/ml polyvinyl-alcohol (PVA) was replaced with foetal bovine serum (FBS) in maturation and culture media. Bovine oocytes were matured in Synthetic Oviduct Fluid (SOF) supplemented with PVA, PVA+5 ng/ml of VEGF, FBS, or FBS+VEGF. Fertilized oocytes were cultured in the same conditions for 8 days. The development of embryos was examined at 48 h post- insemination and on days 6, 7 and 8. The results were analyzed using repeated measures two- factor ANOVA, in which the effects of VEGF and serum were assigned as two factors. The development rate to 4- to 8-cell embryos at 48 h was significantly higher in the PVA+VEGF group than in the PVA group (44.7% and 31.5%, respectively). However, the highest development rate to 4- to 8-cell embryos was obtained from the FBS+VEGF group (58.8%). On day 8, the blastocyst rates were higher in the PVA+VEGF (22.8%), FBS (32.1%, p<0.05) and FBS+VEGF (42.1%, p<0.05) groups than in the PVA group (17.1%). Two- factor ANOVA of the development rates indicates that VEGF had a significant effect, but had no synergistic effect with serum components on early embryonic development. The results of the present study demonstrate that VEGF improves the in vitro developmental competence of bovine oocytes and/or embryos independent of the effect of serum components. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 4 : 495-499)

Hepatic Arterial Chemoembolization for Hepatocellular Carcinoma: Comparison of Survival Rates with Different Embolic Agents

The optimal embolic agent for transhepatic arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) has not been identified. This study reports outcomes of TACE for HCC with Gelfoam powder and polyvinyl alcohol (PVA). Eighty-one patients underwent 152 TACE sessions with Gelfoam powder (n = 41) or polyvinyl alcohol (PVA) and Ethiodol (n = 40) as the embolic agent. Chemotherapeutic drugs were the same for all patients (50 mg cisplatin, 20 mg doxorubicin, 10 mg mitomycin-c). The groups were compared based on number of TACE sessions, maximum tumor size, bilirubin level, aspartate and alanine aminotransferase levels, Child-Pugh score, Model for End-stage Liver Disease score, and hepatitis B or C virus positivity. The number of cases of each Child class in each group was also evaluated. Survival starting from the first TACE session was calculated according to Kaplan-Meier analysis. Forty-eight patients died during the study period, 19 received transplants, and 14 were alive at the end of the study period. The groups were statistically similar in all categories regarding liver function, Child-Pugh score, tumor size, hepatitis status, and percentage of patients with Child class A, B, and C disease. The number of TACE sessions was significantly greater for the Gelfoam powder group (mean, 2.2) versus the PVA group (mean, 1.6; P = .01). Overall survival was similar between groups whether patients who received transplants were included in the analysis (mean, 659 days +/- 83 with Gelfoam powder vs 565 days +/- 71 with PVA; P = .42) or were excluded (mean, 519 days +/- 80 with Gelfoam powder vs 511 days +/- 75 with PVA; P = .93). In similar patient groups, survival after treatment of HCC with TACE with Gelfoam powder or PVA and Ethiodol was similar.

Comparison of particle penetration with non-spherical polyvinyl alcohol versus trisacryl gelatin microspheres in women undergoing premyomectomy uterine artery embolization

The purpose of this study was to compare the depth of vascular penetration of non-spherical polyvinyl alcohol (PVA) versus trisacryl gelatin microspheres (MS) in women undergoing uterine artery embolization (UAE) immediately before transabdominal myomectomy. A total of 17 patients who had been referred for embolization before myomectomy underwent bilateral uterine artery embolization using either 355-500 microm PVA (group A) or 700-900 microm MS (group B). The depth of penetration of the particles was assessed by identifying their presence and location in the resected specimen. Of the 17 women enrolled in this study, 10 were in group A and 6 in group B. One woman underwent embolization using both types of particle and was excluded from the analysis. Embolic particles were significantly (p = 0.048) more frequently located within the fibroid (4/6, 67%) in Group B than Group A (1/10, 10%). Particles were also identified in the perifibroid tissues in 4/6 (67%) in Group B and 4/10 (40%) in Group A, with no statistical difference. There were no procedural complications. MS particles (700-900 microm) penetrate significantly deeper into leiomyomata compared with non-spherical PVA (355-500 microm). MS may therefore confer advantages in UAE, as they may more specifically target the fibroid, allowing an earlier end-point to embolization and minimizing ischaemic damage to normal myometrium and ovaries.

PVA hydrogel sheet macroencapsulation for the bioartificial pancreas

We newly developed a sheet-type macroencapsulation device entrapping rat islets from 3% polyvinyl alcohol (PVA) dissolved in Euro-Collins solution containing 10% fetal bovine serum and 5% dimethyl sulfoxide (PVA+EC) using a freezing/thawing technique. The same encapsulation technique but with 3% PVA dissolved only in double-distilled water (PVA) and a culture of free islets were served as controls. After 14-day culture in the CMRL-1066 medium, the islet recovery rate, morphological changes, insulin content, and insulin secretion were evaluated in vitro to prove the feasibility of this method of encapsulation. We also xenotransplanted the device into the peritoneal cavity of diabetic C57BL/6 mice to check its function in vivo. After 1-day culture, the islet recovery rate and insulin content in the PVA group were significantly lower than that in the PVA+EC and free islet groups. After 14-day culture, only the islets in the PVA+EC group maintained a normal morphology and effective insulin secretory response to high glucose while the response was not observed in the PVA group after 1-day culture and no longer observed in the free islets after 7-day culture. After transplantation of rat islets encapsulated in the PVA+EC device to diabetic C57BL/6 mice, nonfasting blood glucose levels showed a rapid decrease from high glucose levels of pre-transplantation, maintaining significantly lower glucose levels during the whole course of study in comparison with the sham-operated group. Our results indicated that this freezing/thawing macroencapsulation technique using 3% PVA+EC was effective for xenotransplantation of islet cells.

Formation of carbon nanotubes from polyvinyl alcohol using arc-discharge method

The aim of this study is to investigate the possibility of using a polymer material, polyvinyl alcohol (PVA), as an additional carbon source to fabricate carbon nanotubes using arc-discharge method. Experiments were carried out using a graphite anode filled with a mixture of PVA and iron group catalysts. The results indicated that PVA material not only can be used for the formation of carbon nanotubes but also for the formation of some novel carbonaceous structures such as spherical nanoparticles, beaded and sheet-like carbon nanostructures. Furthermore, we found that the catalyst content in the PVA filling mixture should be lower than 50 wt%. In addition, novel catalyst precursors, such as Fe 2(SO 4) 3 · nH 2O or Fe(NO 3) 3 · 9H 2O, were employed to grow carbon nanotubes. The results showed that these catalyst precursors can be used to form carbon nanotubes if their filling content does not exceed 50 wt%.

Separation of IPA/water mixtures by pervaporation: sorption and pervaporation results

Homogeneous membranes were prepared by blending polyvinyl alcohol (PVA) with polyacrylic acid (PAA) and furthermore the blend membrane is cross-linked covalently through an ester linkage formation between a hydroxyl group of PVA and carboxyl group of PAA. These membranes were evaluated for separation of azeotropic isopropyl alcohol (IPA)/water mixtures by pervaporation, that is, a vacuum applying membrane process. The overall and preferential sorption of IPA/water mixtures in cross-linked membranes were determined to investigate the influence of PVA/PAA ratio and of liquid mixture composition. Pervaporation characteristics were also determined as a function of PVA/PAA ratio and of the feed mixture composition. With increasing PAA content in the membranes, solubilities and fluxes decreased and selectivities increased. Because of polarity, water permeated preferentially through the membranes. Sorption results showed the same tendency as pervaporation results.

Viability of inner cell mass of frozen-thawed IVM/IVF bovine embryos using various cryoprotectants

The purpose of this study was to assess the viability of ovine embryos after replacing fetal calf serum (FCS) with polyvinyl alcohol (PVA) in vitrification and warming solutions. Ovine embryos were obtained from superovulated Sardinian breed ewes at 4, 5, 6, and 7 days after insemination. All vitrification and warming solutions were prepared using buffered saline solution with 20% FCS (group a) or 0.1% PVA (group b). Embryos were vitrified in 20 μl of glycerol 3.4 M + ethylene glycol 4.6 M and loaded into the centre of 0.25 ml straws between two columns of sucrose solution (0.5 M), and plunged immediately into liquid nitrogen. After being warmed in a water bath at 35°C for 10 s, the vitrified embryos were moved to 0.25 M sucrose solution for 3 min. Embryos were cultured in TCM-199 after washing with 10% FCS and sheep oviductal epithelial cells up to hatching or re-expansion of the blastocoelic cavity. No significant difference in the viability rates was observed between embryos vitrified/warmed in PVA or FCS solutions. In both groups, the rate of in vitro viability was (P < 0.01) lower at the precompacted and compacted morula stages than at the expanded, hatching or hatched blastocyst stage. In both groups, early blastocysts were less viable than expanded (P < 0.01), hatching or hatched blastocyst (P < 0.05). There was no significant difference in survival rates at days 14 (79 and 76%) and 45 (63 and 59%) after transfer into synchronised recipients between vitrified expanded blastocysts of groups a and b, respectively. These results suggest that it is possible replace serum with PVA in vitrification and warming solutions without reducing in vivo and in vitro viability.

The Use of Sodium Hyaluronate in Freezing Media for Bovine and Murine Embryos

Four experiments were designed to determine whether sodium hyaluronate (SH) may be used to replace newborn calf serum (NCS) in murine and bovine embryo freezing media. A total of 780 mouse and 178 cattle embryos were frozen. Freezing media were prepared in Dulbecco's phosphate-buffered saline supplemented with 20% NCS and 10% glycerol (v/v) (medium A). In experintents I and II, NCS was replaced by 0.1% SH (w/v) in medium B and by 0.1% polyvinyl alcohol (PVA) (w/v) in medium C. In experiments III and IV, NCS was replaced in mouse embryo freezing medium by three different molecular weights of SH as follows: 0.1 or 0.2% (SH-1; <3 × 105 Da) in medium B. by 0.1 or 0.05% (SH-2; 5-7.5 × 105 Da) in medium C, and by 0.1 or 0.025% (SH-3; >1.2 × 106 Da) in medium D. Embryos were frozen and thawed using standard procedures. Glycerol was diluted from embryos after thawing in a single step with 1.0 M sucrose. After 48 h in culture (Ham's F-10 medium for cattle embryos and BWW medium for mouse embryos), embryos were evaluated for development to expanded or hatched blastocysts. Survival rates were compared by X2 analysis. In experiment I, there were no significant differences in mouse embryo survival or development between NCS, SH, and PVA groups (84.1, 79.2, and 83.3%, respectively). In experiment II, there were no significant differences in bovine embryo survival between NCS and SH groups (67.2 and 67.7%), but both had significantly higher survival than the PVA group (37.9%: P < 0.05). In experiment III, there was a significantly lower (P < 0.05) embryo survival rate in the low-molecular-weight SH-1 group (18.6%) than in medium (SH-2)- or high (SH-3)-molecular-weight groups (78.6 and 92.5%, respectively). Although doubling the concentration of SH-1 in experiment IV resulted in improved embryo survival (63.4%), survival rates were significantly higher (P < 0.05) in the medium-molecular-weight (SH-2; 82.3%) and high-molecular-weight (SH-3; 86.0%) groups despite reduced concentrations of these compounds in the freezing medium. Results suggest that SH can be used to replace biological sera in embryo freezing media.

Bovine oviduct cell monolayers for supporting the blastocyst formation of bovine embryos

The purpose of this study was to assess the viability of ovine embryos after replacing fetal calf serum (FCS) with polyvinyl alcohol (PVA) in vitrification and warming solutions. Ovine embryos were obtained from superovulated Sardinian breed ewes at 4, 5, 6, and 7 days after insemination. All vitrification and warming solutions were prepared using buffered saline solution with 20% FCS (group a) or 0.1% PVA (group b). Embryos were vitrified in 20 μl of glycerol 3.4 M + ethylene glycol 4.6 M and loaded into the centre of 0.25 ml straws between two columns of sucrose solution (0.5 M), and plunged immediately into liquid nitrogen. After being warmed in a water bath at 35°C for 10 s, the vitrified embryos were moved to 0.25 M sucrose solution for 3 min. Embryos were cultured in TCM-199 after washing with 10% FCS and sheep oviductal epithelial cells up to hatching or re-expansion of the blastocoelic cavity. No significant difference in the viability rates was observed between embryos vitrified/warmed in PVA or FCS solutions. In both groups, the rate of in vitro viability was (P < 0.01) lower at the precompacted and compacted morula stages than at the expanded, hatching or hatched blastocyst stage. In both groups, early blastocysts were less viable than expanded (P < 0.01), hatching or hatched blastocyst (P < 0.05). There was no significant difference in survival rates at days 14 (79 and 76%) and 45 (63 and 59%) after transfer into synchronised recipients between vitrified expanded blastocysts of groups a and b, respectively. These results suggest that it is possible replace serum with PVA in vitrification and warming solutions without reducing in vivo and in vitro viability.

Use of experimental aneurysms to evaluate wrapping materials

Experimental venous pouch aneurysms in rats were wrapped with muscle, bovine collagen, muslin, cotton, or polyvinyl alcohol. The rats were killed 6 or 12 weeks later, and the aneurysms were compared with control aneurysms. Bovine collagen and muscle were reabsorbed and the aneurysms were similar to the control group. Cotton, muslin, and polyvinyl alcohol caused fibrosis around the aneurysm. However, giant aneurysms were found in the muslin and polyvinyl alcohol group. Cotton appears to be the most suitable material for wrapping aneurysms. The experimental venous pouch aneurysm model in rats can be used to evaluate wrapping materials.