Impact of the Curing Temperature on the Manufacturing Process of Multi-Nanoparticle-Reinforced Epoxy Matrix Composites

This study aims to analyze the effect of the curing temperature of nano-reinforcements during the manufacturing process on the mechanical properties of composites involving graphene (GNP), carbon nanofibers (CNFs), and a hybrid mixture of these two nanoparticles. In this context, the type of nanoparticles, their content, their type of resin, and their hybridization were considered. The results showed that both nanoparticles increased the viscosity of the resin suspension, with an increase of between 16.3% and 38.2% for GNP nanoparticles and 45.4% and 74% for CNFs depending on the type of resin. Shrinkage was also affected by the addition of nanoparticles, as the highest results were obtained with GNP nanoparticles, with a 91% increase compared with the neat resin, and the lowest results were obtained with CNFs, with a decrease of 77% compared with the neat resin. A curing temperature of 5 °C promoted the best bending and hardness performance for all composites regardless of the type of resin and reinforcement used, with improvements of up to 24.8% for GNP nanoparticles and 13.52% for CNFs compared with the neat resin at 20 °C. Hybridization led to further improvements in bending properties and hardness compared with single-reinforcement composites due to a synergistic effect. However, the effectiveness of hybridization depends on the type of resin.

On the origin of the electrical response of vapor grown carbon nanofiber + epoxy composites

The origin of the electrical response of vapor grown carbon nanofiber (VGCNF) + epoxy composites is investigated by studying the electrical behavior of VGCNF with resin, VGCNF with hardener and cured composites, separately. It is demonstrated that the onset of the conductivity is associated to the emergence of a weak disorder regime. It is also shown that the weak disorder regime is related to a hopping depending on the physical properties of the polymer matrix.

251 EVALUATION OF mRNA POLYADENYLATION STATUS OF CELL CYCLE-RELATED GENES IN BOVINE OOCYTES DURING MATURATION: PARTIAL RESULTS

During oocyte growth, transcription activity results in the production of RNA and proteins, which are immediately used or stored. At this time, gene expression is, in part, controlled at the post-transcriptional level through deadenylation and polyadenylation processes. After fertilization, early embryonic cell cycles are mainly supported by maternal mRNA and proteins until the maternal embryonic transition. The extent of the poly A tail of mRNA is known as an important element to determine their stability and can be considered a key marker in embryonic development. Because cell cycle-related genes are implicated in the maturation process and early embryonic cell cycle, study of the poly A tail in oocytes during maturation and early embryonic development may be an useful marker of differential developmental competence. Thus, the aim of the present work was to determine the polyadenylation status of the cell cycle-related genes cdc2, CDK2, CDK4, and Cyclin A, B, D, and E during bovine oocyte in vitro maturation (IVM). A PCR-based technique previously developed by Salles and Strickland (1995 PCR Meth. Appl. 4, 317–321) was used, with some modifications. Cumulus–oocyte complexes obtained from 2- to 8-mm follicles were immediately frozen in liquid nitrogen or IVM for 24 h in TCM-199 supplemented with fetal bovine serum and hormones (LH, FSH, and estradiol). In both cases, cumulus cells were removed by pipetting after a 10-min 0.2% hyaluronidase incubation. The RNA was extracted from pools of 10 immature or IVM oocytes and incubated with phosphorylated oligo-dT and DNA ligase. Thereafter, an anchor adapter [poly(dT) anchor] was targeted to the 5 end of the oligo-dT and incubated with Superscript II (Invitrogen) for reverse transcription. Specific primers were designed at the end of a full known sequence of the genes described above, and PCR was conducted for each gene using a specific primer and the anchor primer. The PCR products were digested with restriction enzymes to verify their specificity and were submitted to polyacrylamide gel electrophoresis. All sequences were amplified in immature and matured oocytes from 2 replicates by using a very small sample. After the restriction enzyme treatment, the amplified products were digested as expected. Although differences in amplicon sizes could be observed between the immature and matured oocytes, these are preliminary results and a higher number of replicates are necessary to determine the changes in the polyadenylation status of these cell cycle-related genes and their biological function. In conclusion, the polyadenylation status of the cell cycle-related genes cdc2, CDK2, CDK4, and Cyclin A, B, D, and E could be effectively performed in small samples, and this may be a powerful tool for studying the differential developmental competence of bovine oocytes and early cleavage embryos. FAPESP.

Sequence variation of the alpha-lactalbumin gene in Holstein and Nellore cows

The alpha-lactalbumin is a subunit of lactose-synthase, an enzyme responsible for lactose production, a disaccharide that influences milk production. Sequence variations of bovine alpha -lactalbumin have been associated with differences in milk yield. This study aimed to analyze allelic frequency differences at position - 1689 (g. A > G) and + 15 (g. A > G) of the alpha-lactalbumin gene in Holstein (Bos taurus) and Nellore (Bos indicus) cows. Blood samples were analyzed from 34 Holstein, 104 Nellore, and 99 Dairy Nellore cows using PCR-RFLP. The different RFLP patterns were sequenced and a novel sequence variation on nucleotide - 46 was identified. An adenine at this position was designated as the A allele and a guanine was designated B allele. The frequencies of alleles A - 1689, A - 46, and A + 15 differed between Holstein and both Nellore breeds. The results show that differences in alpha-lactalbumin allelic variants in the 5'-flanking and the 5'-UTR region might be associated with differences in milk production between Holstein cows and cows from Nellore breeds. However, the lack of difference between Nellore and Dairy Nellore suggests that other sequence variantions that regulate milk production might be responsible for the selection of Dairy Nellore cows with superior milk production.

Association of HLA-A, -B, -C genes and TNF microsatellite polymorphism with psoriasis vulgaris: a study of genetic risk in Brazilian patients

This study investigated the genetic association of HLA class I genes and TNF-alpha microsatellites. HLA-A, -B, -C typing was carried out in 92 psoriasis vulgaris patients and 160 healthy individuals using a PCR-SSP method. 70 patients and 71 controls were typed for five microsatellite polymorphisms, TNFa-e. HLA-B*13 Cw*06, HLA-B*57 Cw*06 and HLA-B*39 Cw*12 haplotypes were found to be increased in patients with psoriasis type I when compared to controls, which could determine the susceptibility to development of psoriasis. TNFa4, TNFb1, TNFe1 and TNFa2 b1 c2 d4 e1 haplotypes showed a decreased frequency (p < 0.05) in psoriasis patients when compared to controls. HLA-B*13 allele and HLA-B*13 Cw*06, TNFa11 b4 c1 d3 e3 haplotypes showed increased frequencies (p < 0.05) in patients with type II psoriasis, which suggests susceptibility to the onset of psoriasis. Our results detected polymorphisms of the HLA class I and microsatellite TNF locus which could be markers of genetic predisposition to the disease.

50 INVESTIGATION OF THE EFFECT OF BUTYROLACTONE I AND CYCLOHEXIMIDE TREATMENT DURING IN VITRO MATURATION OF SWINE OOCYTES

Butyrolactone I and cycloheximide specifically inhibit MPF activation and prevent the resumption of meiosis. The aim of this study was to investigate the kinetics of in vitro maturation of butyrolactone I- and cycloheximide-treated swine oocytes in an attempt to produce cytoplasts for nuclear transfer. Oocytes from slaughterhouse ovaries were randomly allotted to one of 3 treatments; group 1 (n = 102 – control – 22 hours of in vitro maturation in TCM199 supplemented with 3.05 mM glucose, 0.91 mM sodium pyruvate, 10% follicular fluid, 0.57 mM cysteine, 10 ng/mL EGF, 10 IU/mL eCG and 10 IU/mL of hCG and 22 hours of culture); Group 2 (n = 191 – blocking for 10 hours in 12.5 M butyrolactone I and in vitro maturation for 44 hours); and Group 3 (n = 175 – blocking for 10 hours in 5 M cyclohexemide and in vitro maturation for 44 hours). After in vitro maturation, oocytes were fixed and stained for evaluation of meiotic division. The percentage of oocytes at metaphase II (MII) in Groups 1 and 3 (75.49% and 70.29%, respectively) were higher (P < 0.05) than Group 2 (63.35%). Based on these results and in order to increase enucleation rates, we also investigated the proximity of the first polar body (PB) with the metaphase plate (MP) in Groups 1 and 3. After in vitro maturation (36, 40, and 44 hours), oocytes were gently decumulated and incubated in microdroplets (50-μL) of bisbenzimide solution (5 g/mL) to analyze the MP and PB positions. Group 1 (control) at 44 hours of maturation (47.05% – 48/102) and Group 3 at 40, and 44 hours (60.20% – 59/98 and 55.46% – 61/110, respectively) showed similar rates, that were higher (P < 0.05) than Group 1 at 36 hours and 40 hours (4% – 4/100 and 36% – 36/100, respectively) and Group 3 at 36 hours (34.58% – 37/107). In conclusion, Group 1 at 44 hours and Group 3 at 40 or 44 hours provide the best oocytes for enucleation because they showed a high number of matured oocytes with the first polar body and the metaphase plate located proximally. This work was supported by FAPESP 02/10747-1.

82 EVALUATION OF CELL DEATH IN CRYOPRESERVED MOUSE EMBRYOS

Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnology. Recent evidence indicates that apoptosis may be important in determining the viability of cryopreserved embryos. Our goal was to detect apoptosis and characterize and quantify the embryonic cell death caused by cryopreservation. Mouse morulae were collected, selected, and separated into three groups: fresh, slow-freezing, and vitrification. In the slow-freezing procedure, embryos were exposed to 10% ethylene glycol (EG) for 10 min. After loading, the straws were placed into methanol at −7°C for 5 min, seeded and after 5 min cooled at 0.5°C/minute. After 10 minutes at −31°C, straws were plunged into and stored in liquid nitrogen. Slow-frozen straws were thawed in air for 10 s, and then immersed in a 25°C water bath for 20 s. Embryos were vitrified by exposing them to 10% and 20% EG for 5 min followed by 40% EG + 18% Ficoll + 10% sucrose (EFS) for 30 s and the 0.25-mL straws then plunged into and stored in liquid nitrogen. The vitrified straws were warmed by immersing them in 25°C water for 20 s. Cell membrane integrity was assessed by Hoechst and propidium iodide double staining (H/PI). Fresh and thawed embryos were scored (following IETS recommendations) and then fixed after 30 min in PBS + 10% FCS. Morphology and apoptosis were assessed with Haematoxylin-Eosin staining (HE) and by electron microscopy (MET). The number of Grade I embryos recovered after thawing was higher for slow-frozen embryos (61.5%) than vitrified embryos (29.5%). H/PI detected more membrane permeability in the vitrified embryos (69.7%), than in the slow-frozen (48.4%) or non-frozen (13.8%) groups (P < 0,05, Wilcoxon's test). Nuclear evaluation by HE revealed that vitrification and slow-freezing induced pyknosis and chromatin condensation. Mitotic pattern was observed in the fresh and slow-frozen group, but not in vitrification group suggesting that the embryos were either not randomly allocated to the groups or not-treated and fixed at the same age, or that vitrification changed the nuclear status of the embryos. HE staining revealed weakly staining cytoplasm and degenerated cells in the vitrification group (indicating oncosis), while in the slow-frozen group the presence of cytoplasmic condensation and eosinophilic structures indicated apoptosis. The ultrastructure examination confirmed the HE observations. In conclusion, the results demonstrated that staining with HE allows detection of oncosis and apoptosis in cryopreserved embryos. According to these data, vitrification caused more cellular injuries than slow-freezing, and oncosis was the predominant injury. It is important to point that specific molecular apoptosis tests must be performed to confirm these results. This work was supported by FAPESP 04/01252-4.

Geometric reconstruction in left ventricular aneurysm. Surgical aspects and early results

The early results of 79 patients who underwent left ventricular aneurysmectomy with geometric and circular reconstruction in a seven-year experience are analyzed. The most common indication for operation was congestive heart failure (78.4%), either isolated (25.3%) or with angina (53.1%). Sixty patients (76%) were in NYHA class III and 10 (12.6%) in NYHA class IV at the time of surgery. Fifty-eight (73.4%) underwent coronary artery by-pass graft surgery. Hospital mortality was 5.1%, in patients older than 60 (12%), in NYHA class IV (20%), with poor left ventricular function (EF < 0.30-20% and LVED > 25) (14%), and with extensive coronary artery disease (10%) were under increased risk. Low cardiac output and use of intra-aortic balloon pump were also associated risk factors. Other risk factors mentioned in the literature are discussed. There were no deaths from isolated left ventricular aneurysmectomy. The early results of this study and the early and late results of others using the same technique are better than the results obtained in previous studies of different types of correction, suggesting that this is the procedure of choice for treating left ventricular aneurysm.