Group A1 B1 Research Articles

Effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting technology

To investigate the effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting (SLM) technology. A total of 63 specimens of Co-Cr alloy fabricated by SLM were prepared and randomly divided into nine groups (n=7). Each group was treated with different powder particles (A1=50 µm, A2=100 µm, and A3=150 µm) and pressures (B1=0.2 MPa, B2=0.4 MPa, and B3=0.6 MPa) in sandblasting. One sample was randomly selected from each group for microstructure observation by scanning electron microscope (SEM). Ceramic was fired at the center of the specimens. Metal-ceramic bonding strength was measured with universal testing machine. Results were statistically analyzed with SPSS 17.0 software. The mean bond strengths were as follows: Group A1B1: 27.22 MPa±0.95 MPa, Group A1B2: 27.58 MPa±0.47 MPa, Group A1B3: 26.80 MPa±0.71 MPa, Group A2B1: 27.54 MPa±0.78 MPa, Group A2B2: 30.75 MPa±0.43 MPa, Group A2B3: 26.93 MPa±0.88 MPa, Group A3B1: 28.18 MPa±0.93 MPa, Group A3B2: 29.55 MPa±0.57 MPa, and Group A3B3: 28.11 MPa±0.91 MPa. The particle factor of Al₂O₃ and the pressure factor of blasting showed statistical significance (P<0.05). An interaction was observed between the factors of particle and pressure (P<0.05). Mixed fracture mode of all specimens was observed after the shear strength test. In conclusion, metal-ceramic bonding strength reaches the maximum when specimens are sandblasted with 100 µm alumina oxide at 0.4 MPa pressure.

HORMONAL PROFILES OF BLOOD PLASMA ASSOCIATED ESTRUS SYNCHRONIZATION USING DIFFERENT CONCENTRATION OF MAP AND ECG IN BARKI EWES

The current study aimed to characterize the plateau patterns of plasma progesterone in the peripheral circulation during the application of vaginal sponge impregnated with different concentrations of medroxyprogesterone acetate (MAP) and co-treated without and with different doses of equine chorionic gonadotropin (eCG) and its effects on some items of reproductive performance. Determination the onset surges (time and level) of LH and estradiol-17β were also aimed in the study as a necessary pinpoint to the time of ovulation after MAP sponge-eCG treatment. Forty Barki ewes were randomly allocated into 2 main groups (A & B) of equal numbers (n=20/group). Groups A and B were treated with vaginal sponges containing 25 and 50 mg MAP, respectively. On day of sponge's withdrawal, ewes of each main group were randomly reassigned according to eCG dose into three subgroups (1, 2 and 3). Groups A1 and B1 (n=6 each group), served as control, without eCG injection, while groups A2 and B2 (n=7/subgroup) were injected at sponge removal with 300 IU/eCG, whereas, groups A3 and B3 (n=7/subgroup) were injected with 500 IU/eCG. Blood samples were taken immediately before sponge insertion and after the placement subsequently every 2 days and continued to the end of sponge application to studying the plateau pattern of progesterone in the peripheral circulation. Nine hours after sponge removal to 74h latter, blood samples were also taken every 3h and 6h for determination LH and estradiol-17β surges, respectively. The time to onset estrus (h), estrus duration, pregnancy and lambing rates (%) were recorded as reproductive performance measuring related to the study. The started level of plasma progesterone in group A increased gradually with level reaching to its maximum level on days 6 and 8 of sponge application and then rapidly decreases reaching to minimum level on day of sponge removal. On contrast, the patterns of plasma progesterone changes in group B were forcefully increased but with slightly high level from the beginning reaching its highest concentration on day 6 and day 8, then decline gradually to reach lower level on the day of sponge withdraw. The mean time from sponge withdraw to LH and estradiol-17β surges were significantly shorter (P<0.05) in-group A than B and significantly longer (P<0.01) in group A1B1 than other eCG treated groups. Neither MAP nor eCG have significant effects on LH concentration, while, eCG have positive effects on the concentration of estradiol-17β. Generally, the hormonal plateau patterns of group A were associated with acceleration the time to onset estrus with high pregnancy rate. In conclusion, the protocols used for estrus synchronization in sheep are associated with different plateau patterns of circulating reproductive hormones and subsequently affect reproductive performance.

EFFECT OF ESTRUS SYNCHRONIZATION PROTOCOLS ON THE REPRODUCTIVE PERFORMANCE OF BARKI SHEEP

The study aimed to determine the influence of estrus synchronization regimes on reproductive performance in Barki ewes. Forty Barki ewes were randomly allocated into 2 equal groups (A & B). Group A were treated with vaginal sponges impregnated with 25 mg medroxy-progesterone acetate (MAP). On the day of sponge's withdrawal the ewes were reassigned according to eCG dose into three subgroups (A1, A2 and A3). Group A1, served as control, without eCG injection, while groups A2 and A3 were injected IM with 300 and 500 IU/eCG, respectively. The ewes of group B have received vaginal sponge containing 50 mg of MAP. At the day of sponge removal, the ewes were subdivided into 3 subgroups B1, B2 and B3 and treated with eCG as subgroups A1, A2 and A3, respectively. Three fertile rams were subjected to run with ewes for heat detection and natural mating. Blood samples were taken from mated ewes on day 17 post mating, for determination the level of progesterone for pregnancy determination. Results revealed that the incidence of estrus response were 74.60±9.71 and 79.37±9.71 for groups A (25 mg MAP) and B (50 mg MAP), respectively. Irrespective to MAP sponge concentrations, the estrus response in ewes injected with 500 IU/eCG (A3B3) was higher (92.86±11.58%) than group A2B2 (71.43±11.58%) which treated with 300 IU/eCG and control group A1B1 without eCG (66.67±12.51%) with no significant differences. The onset of estrus in ewes of group A was significantly shorter (P<0.05) than group B (36.23±3.18 h vs 46.10±3.41 h). Regardless of MAP, the onset of estrus in control ewes (without eCG) was significantly longer (56.02±4.70 h; P<0.01) than ewes treated with 300 IU/eCG, (36.20±3.82 h) and 500 IU/eCG (31.27±3.49 h). The means of estrus duration were similar with no significant effects of MAP and eCG doses. No significant differences in the pregnancy rates between group A and B, whereas, the pregnancy rate was significantly higher in group A3B3 (92.86±11.21%) than groups A1B1 and A2B2 (50.00±14.24 and 80.00±12.74%, respectively). Neither MAP nor eCG has been a significant effects on the lambing and fecundity rates. In conclusion, Sponges containing 25mg MAP co-treated with 300-500 IU/eCG is suitable protocol for estrus synchronization and improve pregnancy rate in Barki ewes.

Effects of COMTval158met and OPRM1A118G genetic polymorphism on preoperative pain sensitivity

Objective To evaluate the effects of COMTval158met and OPRM1A118G genetic polymorphism on preoperative pain sensitivity in patients.Methods ASA physical status Ⅰ or Ⅱ patients of both sexes,with no history of surgery,aged 20-50 yr,with the body mass index within the normal range,scheduled for elective gynecological or general surgery,were enrolled in the study.Blood samples were taken from the peripheral vein for DNA extraction and COMTval158met and OPRM1A118G genotyping using phenol chloroform extracting method and polymerase chain reaction-restriction fragment length polymorphism,respectively.The patients were divided into 9 groups according to combination of their genotypes:group val/val and A/A (group A1B1),group val/met and A/ A (group A2B1),group met/met and A/A (group A3B1),group val/val and A/G (group A1B2),group val/ met and A/G (group A2B2),group met/met and A/G (group A3B2),group val/val and G/G (group A1B3),group val/met and G/G (group A2B3) and group met/met and G/G (group A3B3).The pain threshold and pain tolerance threshold were measured three times using electrical stimulation after admission to the operating room and the average was calculated.Results Two hundred and seventy-seven subjects were genotyped successfully.There were 68 A1B1,50 A2B1,17A3B1,43 A1B2,46 A2B2,17 A3B2,18 A1B3,10 A2B3 and 8 A3B3.There was no significant difference in the general data of patients among the nine groups (P ＞ 0.05).The OPRM1A118G and COMTval158met allele frequency in Chinese was 0.321 and 0.343,respectively.Compared with group A1B1,the pain threshold was significantly decreased in A2B3 and A3B3 groups,and the pain tolerance threshold was decreased in A1B1,A2B3 and A3B3 groups (P ＜ 0.05).Conclusion There is interaction between COMTval158met and OPRM1A118G genetic polymorphism in their effects on preoperative pain sensitivity and preoperative pain sensitivity is higher in the patients who carry mutation homozygote met158met and 118G. Key words: Pain measurement; Catechol O-methyltransferase; Receptors, opioid, mu; Polymorphism, single nucleotide; Preoperative care

Effects of different degrees and duration of hypothermia on traumatic brain injury in dogs

Objective To investigate the effects of different degrees and duration of hypothermia on severe traumatic brain injury in dogs. Methods Thirty-six one-year-old healthy dogs weighing 13-15 kg were used in this study. Traumatic brain injury model was estabhshed according to the method described by Feeney. Orthogonal design was used in this experiment. Two empirical factors: temperature (factor A) and duration (factor B) were used. Body temperature was maintained at 38 ℃ (A1), 31 ℃ (A2) or35 ℃ (A3) for 6 h (B1) or 12 h (B2).The dogs were divided into 6 groups: group A1B1 , A1B2, A2B1, A2B2, A3B1 and A3B2. Blood gas analysis was performed after the target temperature was maintained for the target duration. Neurological deficit was assessed and scored (0 = no deficit, 500 = severe neurological deficit) and blood samples were obtained at 24, 48 and 72 h after brain injury for determination of serum concentrations of neuron-specific enolase (NSE) and myelin basic protein (MBP) and plasma S-100β protein concentration. Brains were removed at the 72 h after brain injury for determination of Bcl-2 and Bax expression and detection of apoptosis in the brain. Results Hypothermia significantly decreased serum NSE, MBP and plasma S-100β concentrations, neuronal apoptosis and NDS scores;up-regulated Bcl-2 expression and down-regulated Bax expression in brain tissue in the 4 hypothermia groups (group A2B1, A2B2, A3B1 and A3B2) as compared with the control groups (group A1 B1, A1 B2). Best neuroprotective effects were observed in group A3 B1 (35 ℃ for 6 h) in terms of serum NSE, NBP and plasma S-100β concentrations, neuronal apoptosis and cerebral Bax and Bcl-2 expression, but there was no significant difference in the NDS scores among the 4 hypothermia groups. Conclusion Hypothermia can provide neuroprotection in a dog model of traumatic brain injury but the neuroprotective effect is independent of the degree and duration of hypothermia. Key words: Hypothermia, induced; Brain injuries