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Y K Chang

Publications and source records attributed to Y K Chang.

At least 37 records · Page 2Linked to original sources
PubMed1998

Second and early third trimester pregnancy termination by extra-amniotic balloon and intracervical PGE2.

OBJECTIVE: The aim of the study was to investigate the efficacy and safety of an alternative modality using extra-amniotic balloon and intracervical prostaglandin (PG) E2 for termination of second and early third trimester pregnancies. METHOD: Thirty-three pregnant women scheduled for legal termination of pregnancy at 15-32 weeks' gestation were included in the study. Each case received extra-amniotic balloon containing 500-800 ml normal saline and two PGE2 tablets inserted into the cervical canal. RESULTS: All 33 patients achieved a successful termination. The mean induction-to-abortion interval was 12.85 h. There was no significant difference in induction-to-abortion interval between second trimester group and third trimester group. However, the mean duration of balloon distention was longer in the second trimester group. There were no severe complications. CONCLUSION: The combined use of extra-amniotic balloon and intracervical PGE2 tablets is effective, safe and convenient for termination of second and early third trimester pregnancy.

Abortion, Legal↗
PubMed1998

Thromboxane and prostacyclin in maternal and fetal circulation in pre-eclampsia.

OBJECTIVES: A major pathophysiologic change of pre-eclampsia has been attributed to the overproduction of thromboxane A2 (TXA2) mainly from activated platelets. On the other hand, increased biosynthesis of TXA2 has also been reported from preeclamptic placentas. The systemic role of these different sources of TXA2 has not been clarified. The purpose of this study is to define the changes of TXA2 and the antagonizing prostacyclin (PC) in maternal and fetal circulations. METHODS: The stable metabolites of TXA2 and PC [Thromboxine B2 (TXB2) and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), respectively] in the cord and maternal blood of nine patients with pre-eclampsia and nine normal parturients were measured by radioimmunoassay. RESULT: In normal pregnancy, the cord blood contained much higher TXB2 (1697+/-898 vs. 267+/-128 ng/ml, P < 0.01) and 6-keto-PGF1alpha (266+/-263 vs. 12.5+/-3.9 ng/ml, P < 0.05) levels than the maternal blood. In the preeclamptic state, a marked increase of TXB2 was noted in both maternal and cord blood, reaching levels which were significantly higher than during normal pregnancy (2995+/-1103 vs. 267+/-128 ng/ml in maternal blood, P < 0.0001, and 3197+/-1288 vs. 1697+/-898 ng/ml in cord blood, P < 0.005). A less significant increase in 6-keto-PGF1alpha (134+/-10.8 vs. 12.5+/-3.9 ng/ml, P < 0.05) was also noted in the maternal blood. Moreover, the level of TXB2 correlated with the diastolic blood pressure of preeclamptic patients before and after delivery. CONCLUSION: The results suggest an abundant source of eicosanoids in the feto-placental circulation, which does not readily cross the placental barrier. In pregnancy complicated with pre-eclampsia, thromboxane level of both fetal and maternal circulations are markedly increased, which may be responsible for the pathophysiologic changes. The lack of adverse systemic effects on the fetus highlights a placental source of TXA2 of transient bioactivity which is rapidly hydrolyzed to non-active TXB2. Federation of Gynecology and Obstetrics

Adult↗
PubMed1998

Extra-amniotic balloon with PGE2 versus extra-ovular Foley catheter with PGF2alpha in mid-trimester pregnancy termination.

OBJECTIVE: The objective of this study was to compare the efficacy and side effects of two methods of mid-trimester labor induction, extra-amniotic balloon with intracervical prostaglandin (PG) E2 (0.5 mg x 2) vs. extra-ovular Foley catheter with intrauterine PGF2alpha (1 mg/h x6). METHODS: A cohort of 32 and 36 cases indicated for mid-trimester termination was enrolled and managed with extra-amniotic balloon and extra-ovular Foley catheter methods, respectively. Outcomes of induction-to-delivery interval, induction failure, and occurrence of side effects were assessed. RESULTS: There were no statistical differences in maternal age, parity, gestational age or fetal birth weight between the two groups. Compared with the extra-ovular Foley catheter with PGF2alpha group, the induction-to-delivery interval was significantly shorter in the extra-amniotic balloon plus PGE2 group. There was no significant difference in side effects and major complications developed in either groups. CONCLUSIONS: The extra-amniotic balloon with intracervical PGE2 is more efficient in reducing the induction-to-delivery interval for termination of mid-trimester pregnancies than the extra-ovular Foley catheter with intrauterine PGF2alpha.

Abortion, Induced↗
PubMed1995

Recovery and characterization of poly(3-hydroxybutyric acid) synthesized in Alcaligenes eutrophus and recombinant Escherichia coli.

We studied recovery of poly(3-hydroxybutyric acid) (PHB) from Alcaligenes eutrophus and a recombinant Escherichia coli strain harboring the A. eutrophus poly(3-hydroxyalkanoic acid) biosynthesis genes. The amount of PHB degraded to a lower-molecular-weight compound in A. eutrophus during the recovery process was significant when sodium hypochlorite was used, but the amount degraded in the recombinant E. coli strain was negligible. However, there was no difference between the two microorganisms in the patterns of molecular weight change when PHB was recovered by using dispersions of a sodium hypochlorite solution and chloroform. To understand these findings, we examined purified PHB and lyophilized cells containing PHB by using a differential scanning calorimeter, a thermogravimetric analyzer, and nuclear magnetic resonance. The results of our analysis of lyophilized whole cells containing PHB with the differential scanning calorimeter suggested that the PHB granules in the recombinant E. coli strain were crystalline, while most of the PHB in A. eutrophus was in a mobile amorphous state. The stability of the native PHB in the recombinant E. coli strain during sodium hypochlorite treatment seemed to be due to its crystalline morphology. In addition, as determined by the thermogravimetric analyzer study, lyophilized cell powder of the recombinant E. coli strain containing PHB exhibited greater thermal stability than purified PHB obtained by chloroform extraction. The PHB preparations extracted from the two microorganisms had identical polymer properties.

Alcaligenes↗
PubMed1994

Construction of plasmids, estimation of plasmid stability, and use of stable plasmids for the production of poly(3-hydroxybutyric acid) by recombinant Escherichia coli.

Plasmids containing the Alcaligenes eutrophus poly(3-hydroxybutyric acid) (PHB) biosynthetic genes were constructed for the production of PHB in Escherichia coli and plasmid stability was investigated by repeated subculturing without antibiotic pressure. Both pSYL101 (high copy) and pSYL102 (medium copy) were unstable during the subcultures. Higher instability was observed when cells were accumulating PHB. Segregational instability was aggravated by the faster growth of plasmid-free cells and by appearance of non-dividing cells harboring large amount of PHB during the fed-batch culture. Two derivatives, pSYL103 and pSYL104, were then developed by cloning the parB locus of plasmid R1 into pSYL102 and pSYL101, respectively. They showed 100% stability even during PHB synthesis and accumulation over 110 generations. All four plasmids were structurally stable. The final cell mass, PHB concentration, and PHB per dry cell weight (P/X, w/w, %) of 101.4 g l-1, 81.2 g l-1, and 80.1%, respectively, were obtained in 39 h by high cell density culture of XL1-Blue (pSYL104). The final PHB concentration was lower using XL1-Blue (pSYL103), which suggested that high gene dosage was required for the synthesis and accumulation of PHB to a high concentration in E. coli.

Escherichia coli↗
PubMed1994

Prevalence and molecular studies of thalassemia in five aboriginal groups in Taiwan.

A total of 1,342 blood samples from five aboriginal groups in Taiwan, comprising 522 of the Ami, 246 of the Bunum, 227 of the Atayal, 214 of the Paiwan and 133 of the Yami group, were collected. A complete blood count was performed in each case. In subjects with a mean corpuscular volume < 85 fl or hemoglobin (Hb) < 12 gm% (female) or 13 gm% (male), quantitation of Hb A2 and DNA analysis of alpha- and beta-globin genes were performed. Alpha-thalassemia was diagnosed by Southern hybridization of subject's DNA to alpha-, and zeta-globin gene fragments, and to Lo probe if needed. DNA from beta-thalassemia carriers was studied by polymerase chain reaction and direct sequencing. In the Ami, 42 (8.2%) were alpha-thalassemia 1 carriers, 42 (8.2%) were alpha-thalassemia 2 carriers, one had Hb H disease, and four (0.8%) were beta-thalassemia carriers. In the Bunun, one (0.2%) was an alpha-thalassemia 1 carrier, and two (0.4%) were alpha-thalassemia 2 carriers. In the Atayal, one (0.2%) was an alpha-thalassemia 1 carrier. In the Paiwan, seven (3.3%) were alpha-thalassemia 1 carriers, and one (0.5%) was an alpha-thalassemia 2 carrier. In the Yami, none were either alpha- or beta-thalassemia carriers. Diverse genetic origin, intragroup breeding and malarial selection may play a role in the significant differences of thalassemia prevalences both between the Chinese and the aborigines, and among different groups of aborigines.

Female↗
PubMed1994

Elective cesarean section for macrosomia?

BACKGROUND: Fetal macrosomia is associated with increased risk of dystocia and birth trauma. Elective Cesarean section has been recommended for macrosomic fetus to prevent the associated complications. However, the cost/benefit ratio of such practice should be known before it can be considered appropriate. METHODS: The record of 6230 women delivered consecutively at Tri-Service General Hospital were reviewed retrospectively. The occurrence rates of dystocia and birth trauma were compared between normal birthweight group (2500-3999 gm) and macrosomic group (> or = 4000 gm). The complication rates were calculated specifically among those macrosomic infants delivered vaginally. RESULTS: Of the 6230 singleton pregnancies, 207 had an infant weighing at least 4000 gm. One hundred and three macrosomic infants were delivered by Cesarean section. The indication for Cesarean section was dystocia in 25, estimated fetal macrosomia in 30 and other, 48. If only those pregnancies with macrosomic infant allowing an adequate trial of labor were considered, the frequency of Cesarean section for dystocia was 19.1% in the 4000-4999 gm group and 21.4% in the 4500 gm group, compared with 4.4% in the normal birthweight group. No birth trauma occurred in the macrosomic infants delivered by Cesarean section. Of those macrosomic infants delivered vaginally, the frequency of clavicle fracture was 11.8% in the 4000-4499 gm group and 18.2% in the > or = 4500 gm group, compared with 1.2% in the normal birthweight group. Two infants (18.2%) weighing greater than 4500 gm sustained brachial plexus injury. CONCLUSIONS: Elective Cesarean section on macrosomic infants to prevent dystocia is not recommended because most of them can be delivered vaginally. For the very macrosomic infants (> or = 4500 gm), elective Cesarean section is suggested to prevent birth trauma.

Birth Injuries↗
PubMed1992

Gestational and congenital syphilis in Hualien.

From September 1987 to April 1991, 19 pregnant women (0.97%) with syphilis were detected out of 1,955 pregnant women who received prenatal serologic screening at the Buddhist Tz'u-Chi General Hospital. The ages ranged from 17 to 34 years (average, 26). Three cases had recurrent gestational syphilis. The time of diagnosis was: the third trimester, 11 cases; the second trimester, six cases; and the first trimester, two cases. The reasons for late (third trimester) diagnosis were: delay of prenatal care, four cases; failure to screen syphilis in the pregnancy, four cases; and negative first test and late infection, three cases. Late diagnosis and treatment often resulted in poor fetal outcome: syphilitic stillbirth, two cases; probable and possible congenital syphilis, seven cases; and normal infant, two cases. Patients (delivered, five; undelivered, two; abortion, one) who had been diagnosed before the third trimester had a better fetal outcome: possible congenital syphilis, one case; and normal infant, four cases. The perinatal mortality and morbidity were significantly higher in the late diagnosis group (9/11) than in the early diagnosis group (1/5). Pregnant women should be screened in early pregnancy by a serologic test for syphilis. In areas of high prevalence, or in patients at high risk, screening should be repeated in the third trimester and again at delivery.

Adolescent↗
PubMed1991

Utility of the backscattered ultrasonic A-mode signal for the quantitative grading of beef.

A feasibility study applicable to the IN VITRO differentiation of marbling in beef was conducted using signatures extracted from the A-mode backscattered ultrasonic signals. The energy and threshold count of these RF signals correlated well with the percentage of fat in beef sample determined by either extraction chemical test. As the value of n increases from 1 to 3 in the model for the amplitude attenuation in soft tissue, a(f) = aofn, the media of these values of n correspond from linear to nonlinear dependence of frequency in attenuation. This is observed to be analogous to beef with low to high marbling. The regressed gradient of the spectral differences between a reference spectrum from the sample with low percentage of fat and the spectra of other samples of increasing percentage of fat reveal an increase in gradient as the marbling increases. This phenomena is attributed to the change in the center frequency and the spectral bandwidth of a medium with changing physical scatterers' characteristic. These signatures, the energy, the threshold count and the gradient are then used to back predict the percentage of fat (marbling level).

Animals↗
PubMedDate not supplied

Enhancement of kasugamycin production by pH shock in batch cultures of Streptomyces kasugaensis.

Biosynthesis of kasugamycin could be greatly enhanced by applying a nonnutritional stress of pH shock, that is, sequential pH changes from a neutral pH to an acidic condition and then back to the neutral condition. During the acidic period, cell growth decreased to nil. After recovery of the neutral condition, the cell growth resumed after a time lag concurrently with the biosynthesis of kasugamycin at a greatly enhanced rate compared with the control case without a pH shock. In a series of experiments performed to identify the optimal length of pH shock, four different lengths (6, 12, 24, and 48 h) of pH shock were applied. The best result was obtained when pH shock was applied for 24 h, with kasugamycin productivity approximately 7-fold higher than that of the control.

Aminoglycosides↗
PubMedDate not supplied

Recovery of poly(3-hydroxybutyrate) from coagulated Ralstonia eutropha using a chemical digestion method.

For economic recovery of poly(3-hydroxybutyrate) (PHB) from culture broths of Ralstonia eutropha containing PHB, Al-based and Fe-based coagulants were used in the pretreatment step. The coagulated cells were then separated by centrifugation, and PHB was extracted by chemical digestion with a sodium hypochlorite/chloroform dispersion solution. The practical upper limits of dosage were found to be 1, 500 mg-Al/L and 1,000 mg-Fe/L, respectively, for Al- and Fe-based coagulants. When the harvested cells were treated with a 50% sodium hypochlorite/chloroform dispersion solution, PHB recovery and purity were 90-94% and 98-99%, respectively. The influence of the use of coagulants on the PHB recovery process was found to be insignificant. Despite the residual Al and Fe in the recovered PHB (less than 450 mg-Al/kg-PHB and 750 mg-Fe/kg-PHB, respectively), no detectable amounts of Al and Fe were leached from films made of the recovered PHB under acidic conditions. The use of Fe-based coagulants is less recommended because the Fe impurity can cause an unwanted colorization problem in the final product.

Biocompatible Materials↗
PubMedDate not supplied

Continuous culture of immobilized streptomyces cells for kasugamycin production.

Continuous cultures of immobilized Streptomyces kasugaensis, a kasugamycin producer, were carried out on Celite beads. When using a prototype separator for immobilized-cell separation and recycling, the continuous operation could not be sustained for an extended period as a result of an excessive loss of immobilized cells caused by the poor performance of the separator. Accordingly, the immobilized-cell separator was revised to provide better immobilized-cell settling and thus recycling into the reactor. In a subsequent culture using the revised separator, a stable operation was maintained for over 820 h with a high kasugamycin productivity. The kasugamycin productivity ranged from 9.8 to 16.1 mg/L/h, which was about 14- to 23-fold higher than that in a batch suspended-cell culture. When the original feeding medium concentration was doubled at the end of the continuous culture, the productivity became severely impaired for several reasons, which will be discussed. An excessive formation of free cells and loss of immobilized cells through the separator were also observed.

Aminoglycosides↗
PubMedDate not supplied

Production of a desulfurization biocatalyst by two-stage fermentation and its application for the treatment of model and diesel oils.

For the production of oil-desulfurizing biocatalyst, a two-stage fermentation strategy was adopted, in which the cell growth stage and desulfurization activity induction stage were separated. Sucrose was found to be the optimal carbon source for the growth of Gordonia nitida CYKS1. Magnesium sulfate was selected to be the sulfur source in the cell growth stage. The optimal ranges of sucrose and magnesium sulfate were 10-50 and 1-2.5 g x L(-1), respectively. Such a broad optimal concentration of sucrose made the fed-batch culture easy, while the sucrose concentration was maintained between 10-20 g x L(-1) in the actual operation. As a result, 92.6 g x L(-1) of cell mass was acquired by 120 h of fed-batch culture. This cell mass was over three times higher than a previously reported result, though the strain used was different. The desulfurization activity of the harvested cells from the first stage culture was induced by batch cultivation with dibenzothiophene as the sole sulfur source. The optimal induction time was found to be about 4 h. The resting-cell biocatalyst made from the induced cells was applied for the deep desulfurization of a diesel oil. It was observed that the sulfur content of the diesel oil decreased from 250 mg-sulfur x L-oil(-1) to as low as 61 mg-sulfur x L-oil(-1) in 20 h. It implied that the biocatalyst developed in this study had a good potential to be applied to a deep desulfurization process to produce ultra-low-sulfur fuel oils.

Air Pollution↗
PubMedDate not supplied

Development of sporulation/immobilization method and its application for the continuous production of cyclosporin A by Tolypocladium inflatum.

An efficient sporulation/immobilization procedure for immobilized fungal cell culture was developed by modifying an existing immobilized technique to shorten the time and number of steps for sporulation. This method was applied to an immobilized-cell perfusion bioprocess (IPB) for continuous production of CyA, an intracellular secondary metabolite produced by a filamentous fungus, Tolypocladium inflatum. In the IPB, the fungal cells were immobilized in the pores of celite beads (100-500 microm) and a top-driven stirred tank fermentor was used for the culture. The IPB showed good process benefits as demonstrated by the high density of immobilized cells continuously producing CyA-containing free cells. The productivity of cyA-containing free cells in the effluent was very high, ca. 1.0g/(L/h) at a dilution rate of 0.1 h-1, due to the high density of immobilized cells in the fermentor. The CyA productivity was 4.0-6.0 mg/(L/h) which was about 6-10-fold higher than that of batch suspended cell culture. Such an efficient IPB was possible since a decantor was developed in this study, which could effectively separate cell-immobilized beads from the effluent although bead loss slightly increased as the cell loading increased in the latter part of culture. Furthermore, long-term operation of IPB was carried out successfully by employing an in-situ immobilization strategy. It was found that a large number of spores in the fermentation broth in the reactor were entrapped in-situ into the newly supplemented celite beads and then germinated, thus forming new immobilized cells.

Bioreactors↗