• Clinical and Experimental Reproductive Medicine
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• v.19 no.2
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• pp.163-168
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• 1992

This study was carried out to set up the ovum bank for ovum donation and to determine the best freezing method for human immature oocytes. Human immature follicular oocytes were cryopreserved by slow freezing and rapid thawing method. Immature follicular oocytes were treated by propanediol(PROH) solution by 2 and 4 step method in protocols A & B, respectively. In protocol C, immature oocytes were exposed to sucrose prior to treatment of PROH by 4 step method. We compared survival rate, maturation rate, and fertilization rate of immature oocytes among three protocols. Results were as follows. 1. Oocytes treated by the protocol C showed the highest survival rate( 70.3 %) and maturation rate(34.6%) after thawing. 2. Survival rate of oocytes treated by the protocol C was significantly higher than that of the protocol B after thawing(p<0.05). In conclusion, treatment of oocytes with sucrose prior to expose PROH was the best freezing method. Sucrose may have reduced the toxic effect of cryoprotectant to oocytes. We failed to induce fertilization of oocytes, which were treated by any protocols, by conventional insemination method, but obtained 28.8% fertilization rate by using partial zona dissection(PZD) method. This result suggests that micromanipulation(PZD) of the thawed oocytes before insemination will improve the fertilization rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7555-7563
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• 2015

The complex formation from Zn(II) ion and 2-(2-hydroxyethylamino)-2-(hydroxymethyl)-1,3-propanediol (Monotris), Bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane(Bistris) in aqueous solution at $25^{\circ}C$ and at an ionic strength of 0.10 M have been studied potentiometrically. For the Zn(II)-Monotris system, in the Monotris (L) complex $ZnL^{2+}$, one of the hydroxyl oxygen atoms as well as the amine nitrogen of the ligand are coordinated. In basic media, the coordinated hydroxyl group is deprotonated. For the Zn(II)-Bistris system, in the Bistris(L) complex $ZnL^{2+}$, two of the hydroxyl oxygen atoms as well as the amine nitrogen of the ligand are coordinated. In basic media, one of the coordinated hydroxyl groups is deprotonated. In very high basic media, an additional hydroxyl group undergoes deprotonation. The equilibrium constants for the formation of $ZnL^{2+}$, $ZnLH_{-1}{^+}$, $ZnLH_{-2}$, $Zn_2L_2H_{-2}{^{2+}}$ and $Zn_2L_2H_{-3}{^+}$ have been determined.

• Clean Technology
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• v.25 no.2
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• pp.114-122
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• 2019

The synthesis of bio polyol from renewable resources has attracted attention in recent years. In particular, it is important to take advantage of bio polyols in the synthesis of polymers. In this study, a series of dimethylformamide (DMF) based polyurethanes were synthesized using polycarbonate polyol/bio polyol (PO3G: polytrimethylene ether glycol prepared from 1, 3-propanediol produced by fermentation from corn sugar), methylene diphenyl diisocyanate (MDI) and 1,4-butandiol (BD). The properties of prepared polyurethane films and the cell structure of wet type artificial leather were investigated. As the bio polyol content increased, the tensile strength of polyurethane films decreased, however, the elongation at break increased significantly. As a result of thermal characteristics analysis, the glass transition temperature of polyurethanes increased when increasing the content of polycarbonate polyol. As a result of comparing the cell characteristics of wet type artificial leathers prepared in this study, it was found that the number and uniformity of cells formed in the artificial leather samples increased when increasing the content of polycarbonate polyol in polycarbonate polyol/bio polyol. From these results, it was found that DMF-based polyurethane containing an appropriate amount of bio polyol could be used for wet type artificial leather. The bio textile analysis system according to ASTM standard was used to measure the bio carbon content of polyurethane. The content of bio carbon increased proportionally with the increase of bio polyol content used in polyurethane synthesis.

• KSBB Journal
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• v.9 no.3
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• pp.246-252
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• 1994

Enzyme-catalyzed polycondensatlon reaction of aliphatic polyesters with several repeating units was studied using the biocatalytic activities of lipases from different sources. Porcine pancreatic lipase (PPL) was found to be best in utilizing bls(2,2,2-trichloroethyl) glutarate and 1,4-butanediol as substrafes. The reaction was also catalyzed to some extent by the lipases from Humicola lanuginos and Psudomonas sp. In the series of short-chain diols(C2-C4), bis(2,2,2-trichloroethyl) glutarate was iransesterified fastest with 1,4-butanediol and for the long-chain diols (PEG-300-PEG-1000), the reaction was fastest with PEG-400. With PEGs, only monoesterification product was obtained. PPL functioned well in relatively hydrophilic organic solvents such as tetrahydrofuran(THF), ether and acetonitrile. The reaction rate was accelerated as the reaction temperature was raised from $20^{\circ}C$ to $60^{\circ}C$ while Mn values of the reaction products were not affected by the reaction temperature. End group analysis by NMR showed that Mn values of the polymer were in the range of 1500-4000 daltons.

• Clean Technology
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• v.25 no.1
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• pp.7-13
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• 2019

Recently, attention has been paid to obtaining bio-polyols from renewable resources. Successful use of these natural ingredients successfully produced in the industry for the synthesis of various polyurethanes is a very important task. In this study, a series of dimethylformamide (DMF) based polyurethanes were synthesized from methylene diphenyl diisocyanate (MDI)/1, 4-butanediol and bio-polyol (polytrimethylene ether glycol based on 1, 3-propanediol : B-POL)/polyester polyol (polyadipate diol based on 1,4-butandiol : H-PET). The effect of different ratio of bio-polyol (B-POL)/polyester polyol (H-PET) on the physical properties of polyurethane was investigated. As the B-POL content in B-POL/H-PET mixture increased, the glass transition of soft segment (Tgs) and tensile strength of polyurethane decreased, however, the elongation at break and tear strength increased. On the other hand, artificial leather was produced by wet process using synthesized DMF-based polyurethanes. It was found that there was almost no difference in the effect of the B-POL/H-PET composition on the average size and density (the number of cells per unit volume) of the porous cells formed in artificial leather. These results show that there is no problem in using bio-polyol (B-POL) based polyurethane for artificial leather produced by wet process.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.1
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• pp.59-65
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• 2004

Objectives: The aim of this study was to assess toxicities of cryoprotectants. Methods: Toxicities of two cryoprotectants, dimethyl sulfoxide (DMSO) and 1, 2-propanediol (PROH), were investigated using a murine embryo model. Female F-1 mice were stimulated with gonadotropin, induced ovulation with hCG and mated. Two cell embryos were collected and cultured after exposure to either DMSO or PROH. Embryo development was evaluated up to the blastocyst stage. Blastocysts were stained with bis-benzimide to evaluate the cell count and with terminal deoxynucleotidyl transferase mediated dUTP nick labeling (TUNEL) to assess apoptosis. Results: The total cell count of blastocysts that were treated with DMSO at the 2-cell stage was significantly lower than that were treated with PROH ($75.9{\pm}27.0$) or the control ($99.0{\pm}18.3$) (p<0.001). On comparison of two cryoprotectant treated groups, the DMSO treated group showed a decreased cell count compared with the PROH treated group (p<0.05). Both DMSO ($14.2{\pm}1.5$) and PROH ($11.2{\pm}1.4$) treated groups showed higher apoptosis rates of cells in the blastocyst compared with the control ($6.2{\pm}0.9$, p<0.0001). In addition, the DMSO treated group showed more apoptotic cells than the PROH treated group (p<0.001). Conclusions: The potential toxicity of cryoprotectants was uncovered by prolonged exposure of murine embryos to either DMSO or PROH at room temperature. When comparing two cryoprotective agents, PROH appeared to be less toxic than DMSO at least in a murine embryo model.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.111-118
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• 1997

Intracytoplasmic sperm injection (ICSI) recently has been utilized widely as the most successful technique to overcome the unfertilization problem in cases of severe male infertility in couples who could not be treated by conventional IVF. Recently, indications of ICSI have been extended further and more fertilized oocytes become available. Thus, it is necessary to examine the efficiency of freezing the surplus embryos obtained from ICSI. We compared the survival rate and the future outcome of cryopreserved embryos obtained either after conventional IVF or ICSI during the same period. After ICSI or IVF, five best-quality embryos from each patient were transferred in the stimulation cycle and the surplus pronuclear (PN) stage oocytes or multicellular embryos were cryopreserved by slow freezing protocol with 1,2-propanediol (PROH) as a cryoprotectant. A total of 792 embryos from ICSI trial were thawed and 65.2% (516/792) survived. The survival rates of PN stage oocyte, multicellular embryo and PN + multicellular embryo were 63.5%, 68.2%, 64.0%, respectively. After 111 transfers, 34 pregnancies were achieved, corresponding to a clinical pregnancy rate of 30.6% per transfers. We thawed 1033 embryos from IVF trials and 57.5% (594/1033) survived. In IVF cycle, the survival rates of PN stage oocyte, multicellular embryo and PN + multicellular embryo were 58.2%, 65.2%, 40.2%, respectively. Thirty eight clinical pregnancies were established after 134 transfers, corresponding to a pregnancy rate of 28.4% per transfer. The cleavage rate of thawed PN stage oocytes from ICSI trial (61.3%) was significantly higher than those from conventional IVF (53.4%). The developmental rates of good embryo (${\geqq}$ grade II) in thawed PN stage oocytes obtained from conventional IVF and ICSI were 63% and 65%, respectively. We concluded that PN stage oocytes, multicellular embryos resulting from ICSI procedure can be successfully frozen/thawed with reasonable clinical pregnancy rates comparable to those of IVF.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.1
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• pp.59-65
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• 2000

Objective: The purpose of this study was to determine the important factors affecting survival and pregnancy rate in frozen-thawed embryo transfer cycles. Methods: we performed retrospective analysis in 738 cycles of frozen-thawed embryo transfers, in relation to the insemination methods, the freezing stage of embryo, patient's age, infertility factors and the origin of injected sperm in ICSI cycles. After conventional IVF or ICSI, the supernumerary PN stage zygotes or multicellular embryos were cryopreserved by slow freezing protocol with 1,2-propanediol (PROH) as a cryoprotectant. Results: The survival rates of thawed embryos were 69.3% (1585/2287) in conventional IVF group and 71.7% (1645/2295) in ICSI group. After frozen-thawed embryo transfers, 27.0% (92/341) and 32.0% (109/341) of pregnancy rates were achieved in conventional IVF and ICSI group, respectively. There were no significant difference in the survival and pregnancy rates according to the insemination methods, the freezing stage and patient's age. However, the pregnancy rate (36.2%) of male factor infertility was significantly higher than the tubal (27.2%) and other female factor infertility (22.9%). In ICSI group, the origin of injected sperm did not affect the outcome of frozen-thawed embryo transfer cycles. Conclusion: The present study demonstrates that acceptable clinical outcomes can be achieved after the transfer of frozen-thawed embryos regardless of the stage of embryos for freezing, the patient's age and the origin of injected sperm.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.3
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• pp.281-292
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• 1997

The objective of this study was to compare retrospectively the survival and pregnancy rates(PR) of cryopresered-thawed embryos obtained from intracytoplasmic sperm injection (ICSI) or conventional in vitro fertilization (IVF). Ninety-six cycles of cryopresered-thawed embryo transfer (ET) were performed in 79 patients from June, 1996 to September, 1997 and grouped as followings: 20 cycles (16 patients) inseminated by ICSI (ICSI Group) and 76 cycles (63 patients) by conventional IVF (IVF Group). Slow-freezing and rapid-thawing protocol was used with 1.5M propanediol (PROH) and 0.1M sucrose as cryoprotectant. All embryos were frozen-thawed at the two pronuclear (2 PN) stage excluding four cycles in which the early cleavage stage embryos were frozen, and allowed to cleave in vitro for one day before ET. The duration from freezing to thawing was comparable in both groups ($mean{\pm}SD$, $112.1{\pm}80.0$ vs. $124.8{\pm}140.1$ days). The age of female ($31.2{\pm}3.4$ vs. $32.6{\pm}3.3$ years) and the endometrial thickness prior to progesterone injection ($9.4{\pm}2.0$ vs. $9.3{\pm}1.8$ mm) were also comparable in both groups. There was no significant difference in the outcomes of cryopreserved-thawed ET between two groups: survival rate ($85.2{\pm}16.1%$ vs. $82.2{\pm}19.7%$), cleavage rate ($96.9{\pm}6.7%$ vs. $94.7{\pm}13.0%$), cumulative embryo score (CES, $54.5{\pm}31.1$ vs. $49.0{\pm}20.0$), preclinical loss rate (5.0% vs. 5.3%), clinical miscarriage rate (0% vs 29.4%), clinical PR per transfer (35.0% vs. 22.4%), implantation rate (9.9% vs. 5.6%), and multifetal PR (42.9% vs. 17.6%). In conclusion, human embryos resulting from ICSI can be cryopreserved-thawed and transferred successfully, and the survival rate and PR are comparable to conventional IVF.