PubMed Health⌕ Search

Biomedical subjects

J M Lim

Publications and source records attributed to J M Lim.

At least 19 recordsLinked to original sources
PubMed2001

Downregulated expression of integrin alpha6 by transforming growth factor-beta(1) on lens epithelial cells in vitro.

Integrins represent the main cell surface receptors that mediate cell-matrix and cell-cell interactions. They play critical roles in adhesion, migration, morphogenesis, and the differentiation of several cell types. Previous studies have demonstrated that members of the fibroblast growth factor (FGF)-2, transforming growth factor (TGF)-beta(1), and insulin growth factor (IGF)-1 play important roles in lens biology. In particularly, TGF-beta(1) appears to play a key role in extracellular matrix production, cell proliferation, and cell differentiation of lens epithelial cells. In this study we investigated the effects of FGF-2, TGF-beta(1), and IGF-1 on the modulation of integrin receptors using lens epithelial cell lines (HLE B-3 and alphaTN-4) and lens explants. We found that the expression of integrin alpha6 is downregulated by TGF-beta(1), but is not responsive to FGF-2 or IGF-1. The promoter activity of the integrin alpha6 gene decreased upon TGF-beta(1) treatment in a transient transfection assay, and flow cytometric analysis demonstrated the reduced expression of integrin alpha6 by TGF-beta(1), whereas significant changes were not observed in the level of integrin alpha6 after the addition of FGF-2. These findings suggest that the reduced expression of integrin alpha6 caused by TGF-beta(1) might play a role in the activation of the cell cycle genes required during the fiber differentiation of the lens.

Animals↗
PubMed2001

A separate procedure of fusion and activation in an ear fibroblast nuclear transfer program improves preimplantation development of bovine reconstituted oocytes.

This study was conducted to examine whether preimplantation development of bovine ("HanWoo," Bos Taurus corcanae) oocytes reconstituted with ear fibroblasts could be improved by a modified procedure of fusion and activation. In Experiment 1, enucleated oocytes were reconstituted with ear fibroblast by a combined procedure of electric fusion and activation at either 24 or 28 hours after IVM. The 28 hours reconstitution yielded more blastocysts (4% vs. 21%, P = 0.0025) and higher ratio of blastocysts per 2-cell embryos (0.05 vs. 0.25, P = 0.003) than the 24 hours. In Experiment 2, enucleated oocytes were reconstituted by one of the three fusion and activation protocols; 1) a combined procedure of electric fusion and activation at 28 hours after IVM, 2) a combined procedure of electric fusion and chemical activation at 28 hours, and 3) a separate procedure of electric fusion at 24 hours and chemical activation at 28 hours. When compared two combined procedures, chemical activation with 5 microM ionomycin for 4 minutes did not promote embryo development and significantly reduced the fusion rate (42% vs. 53%, P = 0.0395). However, significant (P < 0.0113) increases in the development to 2-cell (90% vs. 70 to 74%) and blastocyst (47% vs. 7 to 13%) stages and in the ratio of blastocysts per 2-cell embryos (0.52 vs. 0.11 to 0.18) were obtained by a separate procedure of electric fusion and chemical activation than by the combined procedures. This separate protocol did not reduce the fusion rate compared with the combined procedures (58%). In conclusion, improved development of oocytes reconstituted with ear fibroblasts was achieved by undergoing a separate procedure of electric fusion and chemical activation 4 hours apart.

Animals↗
PubMed2001

Cryopreservation of ICR mouse oocytes: improved post-thawed preimplantation development after vitrification using Taxol, a cytoskeleton stabilizer.

OBJECTIVE: To establish an effective cryopreservation method. DESIGN: In vitro model study. SETTING: Infertility Medical Center, Pochon CHA University. ANIMAL(S): Four-week-old ICR mice superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin. INTERVENTION(S): Vitrified-thawed oocytes were fertilized and subsequently cultured in vitro. MAIN OUTCOME MEASURE(S): Post-thawed development, chromosome/spindle normalities, and blastocyst quality. RESULT(S): More cumulus-enclosed oocytes were fertilized and developed to the 8-cell stage after vitrification and thawing than denuded oocytes. However, cryopreserved oocytes of both types had lower spindle and chromosome normalities than fresh oocytes, which resulted in reduced developmental competence after thawing. The addition of 1 microM of Taxol, a cytoskeleton stabilizer, to vitrification solution greatly promoted the blastocyst formation of vitrified-thawed oocytes, compared with no addition (24.0% vs. 58.6%). No difference in blastocyst quality, which was evaluated by blastomere and inner cell mass cell numbers and inner cell mass cell per trophoblast ratio, was found between fresh oocytes and oocytes vitrified with Taxol. CONCLUSION(S): A vitrification solution consisting of 5.5 M ethylene glycol, 1.0 M sucrose, 10% fetal bovine serum, and 1 microM Taxol greatly improved post-thawed development of vitrified oocytes.

Animals↗
PubMed2001

Establishment of an animal embryo culture system containing various embryotropins and its efficacy for culturing ICR mouse one-cell embryos derived in vivo or in vitro.

OBJECTIVE: To develop an effective ICR mouse embryo culture medium. DESIGN: In vitro model study. SETTING: University-affiliated hospital. ANIMALS: Four-week-old, superovulated mice. INTERVENTION(S): In vivo- or in vitro-derived one-cell embryos were cultured in preimplantation-1 medium (P-1). MAIN OUTCOME MEASURE(S): Preimplantation development. RESULT(S): In vivo-derived embryos were cultured in BSA-containing P-1, to which one of the following substances was added: [1] no addition, [2] amino acids (aa), [3] aa+hemoglobin (hb), [4] aa+hb+cysteine (cys), [5] aa+hb and glucose (glu) added at the four-cell, or [6] aa+hb and glu+cys added at the four-cell stage. More (P<0.05) blastocysts developed after aa or aa+hb addition than after no addition, and glu addition to such medium further stimulated the formation (54%). In P-1 with aa+glu, the addition of 1 microg/mL hb was optimal. Additional improvement of blastocyst formation (78%) was achieved by ethylenediaminetetraacetic acid (EDTA), supplementation and bovine serum albumin replacement with polyvinyl alcohol (PVA) did not inhibit the development. P-1 supplemented with aa, hb, glu, EDTA, and PVA also supported the development of in vitro-derived embryos (70%). CONCLUSION(S): A modified P-1 medium was developed, and it supported the development of both in vivo- and in vitro-derived ICR mouse embryos.

Amino Acids↗
PubMed2001

Births of freemartins derived from embryos reconstructed with ear fibroblasts.

Although the combination of artificial insemination (AI) and embryo transfer (ET) is effective for preventing large offspring syndrome in clone cattle production, it may cause freemartinism. In this study, 51 reconstructed embryos were transferred to artificially inseminated recipients. Of those 9 twin pregnancies, three delivered male and female offsprings. The females had tufts of long coarse hair and short blind pouch at the vaginal end. At necropsy, hypoplastic testicles and epididymis, which connected to the uterus through the spermatic cord, were found and seminal vesicles were also noted. All females had mixed sex chromosome configuration (60, XX and 60, XY). These results suggest that the combined ET program can cause freemartinism, which reduces the efficiency of clone cattle production.

Animals↗
PubMed2001

Anaemia in the critically ill--the optimal haematocrit.

INTRODUCTION: The optimal haematocrit for the critically ill patient is undetermined. METHODS: This review focuses on clinical and experimental papers regarding the aetiology and management of anaemia from the Medline database. Data from our intensive care unit (ICU) were also included. RESULTS: Anaemia may result from frequent blood sampling, gastrointestinal bleeding, surgical blood loss, impaired erythropoeitic response, and nutritional deficiencies of iron, vitamin B12 and folate. Available data on the minimum tolerated Hct are conflicting. There has been emphasis that transfusions should not be based on a single "trigger". Recent data suggest a linear relationship between Hct and cerebral oxygen delivery (DO2). There is evidence that anaemia increases the mortality, and the risk is higher in patients with cardiovascular disease. Conversely, transfusions are not without risks, which include transmission of infections, incompatibility reactions and immunomodulation. Restricting blood transfusion has been shown to result in lower 30-day mortality in certain patient groups. Minimising blood loss and nutritional support are important. Alternative strategies to transfusion include erythropoeitin and blood substitutes like cell-free haemoglobin, perfluorocarbon emulsions and liposome-encapsulated Hb. Hyperbaric oxygen has also been tried. CONCLUSION: Oxygen consumption requires oxygen delivery. Haematocrit delivers oxygen. However, if oxygen delivery is not limited by haematocrit or is achieved by other means, then the concept of the optimal haematocrit is irrelevant. There are currently no guidelines for the management of anaemia in the critically ill.

Anemia↗
PubMed2000

Freezing immature oocytes.

The establishment of a long-term preservation system for mammalian oocytes is important for the development of both biological and medical sciences. A number of efforts have been made to develop this system. In human reproductive medicine, the development of an oocyte cryopreservation system can improve the efficacy of the current assisted reproductive technology (ART) for infertile patients with severe reproductive disorders. In this article, the technical development of cryopreservation programs for human oocytes and its biological background were reviewed. Clinical outcome after the use of this technology was further introduced.

Cell Culture Techniques↗
PubMed2000

Exogeneous substances affecting development of in vitro-derived bovine embryos before and after embryonic genome activation.

Three experiments were conducted to evaluate how exogenous substances [fetal bovine serum (FBS), arachidonic acid (AA), glutathione (GSH), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF), fibroblast growth factor (FGF), insulin, transferrin and selenium (ITS)] affect preimplantation bovine embryo development. Cumulus-oocyte complexes (COC) were matured and fertilized in vitro, and their development was monitored up to 192 h post insemination in a two-step culture system. In Experiment 1, inseminated oocytes were cultured in modified bovine embryo culture medium (mBECM) supplemented with FBS or BSA for up to 60 h post insemination, and the resultant 8-cell embryos were then cultured singly in mBECM supplemented with AA+GSH+PDGF+TGF. More (P<0.005) blastocysts were derived from 8-cell embryos produced in media containing FBS than BSA. In Experiment 2, the 8-cell embryos produced in mBECM supplemented with FBS were cultured singly in mBECM as follows: 1) no supplementation; 2) AA and GSH or 3) AA, GSH, PDGF and TGF. Compared with no supplementation, a significant (P<0.05) increase in the proportion of 16-cell embryos and morulae was obtained after the addition of either AA+GSH or AA+GSH+PDGF+TGF. In Experiment 3, oocytes were cultured singly in mBECM as follows: 1) no supplementation; 2) AA+GSH+PDGF+TGF; 3) AA+GSH+PDGF+TGF and FGF; 4) AA+GSH+PDGF+TGF and ITS; 5) AA+GSH+PDGF+TGF, FGF and ITS or 6) FBS. Eight-cell embryos grown in each system were subsequently cultured singly in mBECM with AA+GSH+PDGF+TGF. More (P<0.05) 16-cell embryos were obtained in medium supplemented with either AA+GSH+PDGF+TGF and ITS or FBS than in unsupplemented medium. Fewer (P<0.05) oocytes developed to the 8-cell stage with the addition of AA+GSH+PDGF+TGF and FGF than without. In conclusion, embryo development to the blastocyst stage is regulated by exogenous AA, GSH, PDGF, FGF and ITS in a stage-specific manner.

Animals↗
PubMed2000

Pregnancies and deliveries after in vitro maturation culture followed by in vitro fertilization and embryo transfer without stimulation in women with polycystic ovary syndrome.

OBJECTIVE: To improve the efficacy of an IVF-ET program for unstimulated patients with polycystic ovary syndrome (PCOS) with the use of culture for oocyte maturation. DESIGN: Prospective studies with the comparison of different ET procedures from March 1995 through February 1998. SETTING: University-affiliated hospital. PATIENT(S): Ninety-four cycles in 64 consenting patients with PCOS. INTERVENTION(S): Immature oocytes were retrieved from unstimulated patients with PCOS and subsequently cultured and fertilized in vitro. Zygote intrafallopian transfer (ZIFT), uterine ET, or a combined approach of ZIFT + uterine ET was subsequently performed. MAIN OUTCOME MEASURE(S): Laboratory and clinical data. RESULT(S): Among 1, 280 immature oocytes (13.6 +/- 7.5 oocytes per patient) retrieved, 89% (1,139) were morphologically normal, and 62.2% (708/1,139) of the normal oocytes matured in vitro after culture for 48 hours. When intracytoplasmic sperm injection was performed, 68% (481/708) developed to the normal pronuclear stage, and 88.1% of the embryos cocultured with Vero cells (266/302) cleaved. Eighty-five ET cycles were conducted and pregnancy was established in 23 cycles (27.1%), which consisted of 8 after uterine ET and 15 after a combined approach. Seventeen patients delivered 20 normal infants. CONCLUSION(S): The IVF-ET method using no ovarian stimulation followed by in vitro maturation culture can be a feasible assisted reproductive technology for treatment of PCOS with various complications.

Adult↗
PubMed2000

Embryotropic role of hemoglobin and ethylenediaminetetraacetic acid in preimplantation development of ICR mouse 1-cell embryos.

OBJECTIVE: To evaluate embryotropic action of hemoglobin (Hb) and ethylenediaminetetraacetic acid (EDTA) on preimplantation embryo development. DESIGN: In vitro model study using mouse embryos. SETTING: University affiliated hospital, Pochon CHA University. ANIMALS: Four-week-old block strain ICR mice naturally mated after superovulation. INTERVENTION(S): One-cell embryos were cultured in serum-free, modified preimplantation-1 medium, to which 1 microg/ml Hb and/or 0.1 mM EDTA were added. MAIN OUTCOME MEASURE(S): Preimplantation development and blastomere number. RESULT(S): More (P<.05) 1-cell embryos developed to the 4-cell (52% vs. 67%-84%), 8-cell (48% vs. 65%-81%), and blastocyst (40% vs. 61%-79%) stages after the addition of hemoglobin (Hb) and/or EDTA than after no addition. Highest proportion of embryos developed to each stage after the combined addition of Hb+EDTA. EDTA specifically stimulated the development before the 8-cell stage, which was as similar as Hb+EDTA. On the contrary, higher ratio of morula to blastocyst transformation was obtained after the addition of Hb or Hb+EDTA than after no addition (0.76 vs. 0.96-0.98). Significant increases in the cell number of blastocysts (46.5-47.2 vs. 53.2 cells), inner cell mass (ICM) cells (16.7-17.5 vs. 21 cells), and the ratio of ICM cells to trophoblasts (0.3-0.37 to 0.39) were found after the combined addition of Hb+EDTA, compared with no addition or with the addition of EDTA or Hb alone. CONCLUSIONS: Hb and EDTA have stage-specific effects on supporting preimplantation embryo development; Hb promotes both the development before the 8-cell stage and the morula to blastocyst transformation, whereas EDTA mainly promotes the development to the 8-cell stage. The combined exposure of embryos to Hb and EDTA improves not only preimplantation development but also the growth and quality of blastocysts.

Animals↗
PubMed2000

In vitro blastocyst formation of human oocytes obtained from unstimulated and stimulated cycles after vitrification at various maturational stages.

OBJECTIVE: To evaluate the developmental competence and chromosomal normality of oocytes vitrified at various times after maturation culture. DESIGN: In vitro model study. SETTING: A university-affiliated hospital. PATIENT(S): Unstimulated women who underwent cesarean section or oophorectomy and infertile women who underwent a long protocol of GnRH stimulation. INTERVENTION(S): Retrieved oocytes were vitrified at 0 or 48 hours after culture in unstimulated cycles and at 0, 8-15, or 24-28 hours after culture in stimulated cycles. MAIN OUTCOME MEASURE(S): Postthaw morphologic normality, maturation, fertilization, cleavage, blastocyst formation, and chromosome number. RESULT(S): In the 53 oocytes that were obtained from unstimulated cycles, no statistically significant differences were found in rates of morphologic normality (range, 56%-63%) or fertilization (range, 31%-37%) according to the time of vitrification. In the 50 oocytes that were obtained from stimulated cycles, more of those that were vitrified at 24-28 hours were morphologically normal than those that were vitrified at 0 or 8-15 hours. Regardless of these differences, high cleavage rates (83%-100%) were obtained that did not differ significantly among the treatment groups. In both cycles, 20%-43% of cleaved oocytes developed to the blastocyst stage by 6 days after IVF. All the karyotyped blastocysts, three from unstimulated cycles and four from stimulated cycles, had a normal number of chromosomes. CONCLUSION(S): Vitrified and thawed oocytes from unstimulated or stimulated cycles developed to the blastocyst stage, regardless of when vitrification occurred; the number of chromosomes in the blastocysts was normal.

Adult↗
PubMed2000

Evaluation of the pharmacokinetics and electrocardiographic pharmacodynamics of loratadine with concomitant administration of ketoconazole or cimetidine.

AIMS: To evaluate whether ketoconazole or cimetidine alter the pharmacokinetics of loratadine, or its major metabolite, desloratadine (DCL), or alter the effects of loratadine or DCL on electrocardiographic repolarization in healthy adult volunteers. METHODS: Two randomized, evaluator-blind, multiple-dose, three-way crossover drug interaction studies were performed. In each study, subjects received three 10 day treatments in random sequence, separated by a 14 day washout period. The treatments were loratadine alone, cimetidine or ketoconazole alone, or loratadine plus cimetidine or ketoconazole. The primary study endpoint was the difference in mean QTc intervals from baseline to day 10. In addition, plasma concentrations of loratadine, DCL, and ketoconazole or cimetidine were obtained on day 10. RESULTS: Concomitant administration of loratadine and ketoconazole significantly increased the loratadine plasma concentrations (307%; 90% CI 205-428%) and DCL concentrations (73%; 62-85%) compared with administration of loratadine alone. Concomitant administration of loratadine and cimetidine significantly increased the loratadine plasma concentrations (103% increase; 70-142%) but not DCL concentrations (6% increase; 1-11%) compared with administration of loratadine alone. Cimetidine or ketoconazole plasma concentrations were unaffected by coadministration with loratadine. Despite increased concentrations of loratadine and DCL, there were no statistically significant differences for the primary electrocardiographic repolarization parameter (QTc) among any of the treatment groups. No other clinically relevant changes in the safety profile of loratadine were observed as assessed by electrocardiographic parameters (mean (90% CI) QTc changes: loratadine vs loratadine + ketoconazole = 3.6 ms (-2.2, 9.4); loratadine vs loratadine + cimetidine = 3.2 ms (-1.6, 7.9)), clinical laboratory tests, vital signs, and adverse events. CONCLUSIONS: Loratadine 10 mg daily was devoid of any effects on electrocardiographic parameters when coadministered for 10 days with therapeutic doses of ketoconazole or cimetidine in healthy volunteers. It is concluded that, although there was a significant pharmacokinetic drug interaction between ketoconazole or cimetidine and loratadine, this effect was not accompanied by a change in the QTc interval in healthy adult volunteers.

Adult↗
PubMed2000

Relationship between fetal femur diaphysis length and neonatal crown-heel length: the effect of race.

OBJECTIVE: To determine whether racial differences affect the relationship between the fetal femur diaphysis length and the neonatal crown-heel length. DESIGN: A prospective study in a teaching hospital with a multiracial population. SUBJECTS: Four hundred and fifty pregnant women (150 Malays, 150 Chinese and 150 Indians) who delivered live infants. METHODS: Ultrasound scan measurement of the fetal femur diaphysis length was carried out within 48 h of delivery in all cases. The relationship between the neonatal crown-heel length and the femur diaphysis length was obtained by regression using the method of least squares. Dummy or indicator variables were used to determine the effect of race on the relationship. RESULTS: The relationship between the neonatal crown-heel length and the femur diaphysis length in all three races was well described by a linear model but a quadratic model described the relationship better. There was no significant difference in relationship of the neonatal crown-heel length and the femur diaphysis length between the Malay and Chinese populations, but the relationship in the Indian population was significantly different was from both the Chinese and Malay. For a given femur diaphysis length, the crown-heel length of the Indian population was found on average to be 1.1 cm shorter than the crown-heel length of the Malay and Chinese populations. CONCLUSION: Differences in fetal body proportions exist between some races. The longer femur diaphysis length noted in certain races does not necessarily imply that the corresponding crown-heel length is longer. These inter-racial differences may increase the error of fetal weight and length estimates if formulae, which have been derived from samples racially dissimilar to that of the target population are used.

Adolescent↗
PubMed2000

Development of porcine oocytes from preovulatory follicles of different sizes after maturation in media supplemented with follicular fluids.

The development of porcine oocytes from large (3.1-8.0 mm in diameter) or small (<3.1 mm) follicles was examined after maturation culture in medium containing porcine follicular fluid (pFF). Large follicles yielded larger (256 microm v. 221 microm; P<0.05) cumulus-oocyte complexes and more (22 v. 14%) morphologically normal oocytes than small follicles (Experiment 1). In Experiments 2-4, maturation media supplemented with mixed pFF (10%) from small and large follicles was used. More oocytes from large follicles matured (58% v. 91%), formed pronuclei (81% v. 90%) and developed to the blastocyst stage (2% v. 10%) than oocytes from small follicles. In Experiments 5-7, the effects of pFF collected from either small or large follicles on oocyte development were examined. Regardless of the source of oocytes, large-follicle-derived pFF more significantly enhanced preimplantation development than did small-follicle-derived pFF. The highest rate of blastocyst formation (16%) was found when oocytes from large follicles were cultured in maturation medium containing large-follicle-derived pFF. These results suggest that oocytes from large follicles have greater developmental potential than oocytes from small follicles, and that the origin of pFF, which is added to the maturation media, might be an important factor for improving in vitro development of porcine oocytes.

Animals↗
PubMed1999

Development of bovine IVF oocytes cultured in medium supplemented with a nitric oxide scavenger or inhibitor in a co-culture system.

Bovine IVF oocytes were cultured in modified bovine embryo culture medium (mBECM) supplemented with either a nitric oxide (NO) scavenger, hemoglobin (Hb, 1 microg/mL) and/or a NO synthesis inhibitor, L(omega)-nitro-L-arginine methyl ester (L-NAME, 1 or 1000 nM) in a cumulus-granulosa cell co-culture system. In Experiment 1, a total of 1,675 cumulus-oocytes complexes was collected for 7 mo and cultured to the blastocyst stage in mBECM with or without Hb after IVM and IVF. There were significant (P<0.0024) model effects of Hb addition and month of oocyte collection on embryo development. A significant (P<0.0023) monthly variation was detected in all developmental stages. However, addition of Hb to mBECM consistently enhanced embryo development to the blastocyst stage over all months. No statistical differences were found in the interaction between Hb addition and month except for the cleavage rate. Overall, a greater percentage of oocytes developed to the 8-cell (P<0.0459), 16-cell (P<0.001), morula (P<0.0013) and blastocyst (P<0.0024) stages after the addition of Hb. In Experiment 2, addition of L-NAME to mBECM supplemented with Hb did not further stimulate prehatched development. In conclusion, the promoting effect of Hb on in vitro development of embryos is highly repeatable over an extended period of time.

Animals↗
PubMed1999

Improved human oocyte development after vitrification: a comparison of thawing methods.

OBJECTIVE: To evaluate the developmental competence of vitrified human oocytes thawed using two different methods to establish an effective cryopreservation protocol. DESIGN: In vitro model study. SETTING: University-affiliated hospital. PATIENT(S): Patients who underwent a long protocol of ovarian stimulation with GnRH and gonadotropins. INTERVENTION(S): Vitrified oocytes from the patients were thawed using either a four-step method with 2.5-minute intervals or a four-step method with 5-minute intervals. MAIN OUTCOME MEASURE(S): Morphologic normality, maturation, fertilization, and development of the oocytes to the blastocyst stage. RESULT(S): The two thawing methods did not significantly affect the morphologic normality (84%-100%), maturation (75%-100%), fertilization (38%-71%), polyspermy (more than three pronuclei; 0%-20%), or parthenogenetic activation (only female pronucleus; 0%-8%) of the vitrified oocytes. However, more of the vitrified oocytes developed to the two-cell (71%-100% versus 50%-67%), four-cell (71%-93% versus 0%-50%), eight-cell (46%-71% versus 0%), and blastocyst (23%-36% versus 0%) stages after thawing using the four-step method with 2.5-minute intervals than using the four-step method with 5-minute intervals. CONCLUSION(S): Vitrified human oocytes developed to the blastocyst stage with IVF. A four-step thawing method with 2.5-minute intervals was more effective in supporting preimplantation embryo development than a four-step thawing method with 5-minute intervals.

Adult↗