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T H Chiu

Publications and source records attributed to T H Chiu.

At least 73 records · Page 4Linked to original sources
PubMed1993

Expression of alpha 1, alpha 5, and gamma 2 GABAA receptor subunit mRNAs measured in situ in rat hippocampus and cortex following chronic flurazepam administration.

Prolonged benzodiazepine treatment of rats results in anticonvulsant tolerance in vivo. Studies of in vitro hippocampal slices following 1 wk flurazepam administration show reduced GABA-mediated inhibition in the CA1 region, and a decrease in GABAA agonist and benzodiazepine potency to inhibit CA1 pyramidal cell-evoked responses. To investigate the molecular basis of benzodiazepine tolerance in the hippocampus, in situ hybridization techniques were used to evaluate the expression of the mRNAs for the alpha 1, alpha 5, and gamma 2 subunits of the GABAA receptor in the hippocampal formation and frontal cortex of chronic flurazepam-treated rats. A discretely localized decrease in alpha 1, but not alpha 5 or gamma 2 mRNA expression was found in the CA1 region (35-40%) and in layers II-III and IV of cortex (50-60%) 2 d after cessation of flurazepam treatment. The decrease in the expression of alpha 1 subunit mRNA in cortex is similar to that reported following other chronic benzodiazepine treatment regimens. This is the first report of a reduction in alpha 1 subunit mRNA expression in the hippocampal formation.

Animals↗
PubMed1993

Electrophysiological actions of alfentanil: intracellular studies in the rat locus coeruleus neurones.

1. The electrophysiological effects of alfentanil on 156 neurones of the rat locus coeruleus were investigated by use of intracellular recordings from the in vitro brain slice preparation. 2. Bath application of alfentanil (5-100 nM) reversibly decreased the firing rate of all neurones tested in a dose-dependent manner, with an IC50 4.1.nM. 3. Based on inhibition of the spontaneous firing rate, alfentanil was 22 times more potent than morphine. 4. At 100 nM, alfentanil produced a complete inhibition of firing of all neurones tested (n = 62); the inhibition was accompanied by a membrane hyperpolarization 17.0 +/- 0.8 mV (range 6.1-30.3 mV, n = 62) and a reduction in input resistance 26.4 +/- 1.7% (range 6.5-53%, n = 51). 5. The effects of alfentanil were antagonized by naloxone, with a dissociation equilibrium constant of 2.7 +/- 0.4 nM (n = 6). 6. The reversal potential for the alfentanil-induced hyperpolarization was -110 +/- 2 mV (n = 9), which is approximately the potassium equilibrium potential. 7. The alfentanil-induced hyperpolarization was blocked by caesium chloride and barium chloride. 8. These results indicate that alfentanil binds to mu-opioid receptors on the cell membrane of neurones of the locus coeruleus. This leads to opening of the inward-going rectification potassium channels, resulting in the observed hyperpolarization of the membrane.

Alfentanil↗
PubMed1993

Deep vein thrombosis during pregnancy.

Antepartum deep vein thrombosis is quite rare in Chinese women during pregnancy. An adequate diagnosis and early treatment are extremely important as the deep vein thrombosis can embolize, in particular, to the pulmonary vasculature. We present a case of pregnancy at 36 weeks gestation complicated by deep vein thrombosis. The objective diagnosis of deep vein thrombosis for obstetric patients is the noninvasive Doppler ultrasound and plethysmography. An early diagnosis is important to reduce maternal and fetal risks related to embolization. Continuous therapy of low dose intravenous heparin is safe and effective during pregnancy.

Adult↗
PubMed1993

Maternal renal artery Doppler flow-velocity waveform in preeclampsia. A preliminary report.

By use of duplex Doppler ultrasonography, we preliminarily studied 30 normal pregnancies (control group) and 30 patients with preeclampsia (study group) before treatment. The peak systolic flow height to end diastolic flow height (S/D) ratio of the maternal right and left renal arteries of both groups were compared and analyzed. The results showed that there were no significant differences between the right and left renal arteries in either group, but unexpectedly the S/D ratio of the renal artery on both sides in preeclamptic patients was significantly lower than in normal pregnant women (mean +/- SD, 2.07 +/- .12 vs. 2.41 +/- .12, respectively, P < .001). The lower S/D ratio of the renal artery may reflect a decrease in renovascular resistance and an increase in renal perfusion. These findings were the reverse of what might be expected from an elevated vascular resistance and hypoperfusion model.

Adult↗
PubMed1992

Effects of exogenous GM1 ganglioside on LTP in rat hippocampal slices perfused with different concentrations of calcium.

Combined actions of GM1 ganglioside molecules and Ca2+ ions on long-term potentiation (LTP) of the hippocampal CA1 synapses were examined in slice preparations. Application of exogenous GM1 ganglioside significantly enhanced LTP. Antigenic blocking of endogenous GM1 ganglioside by applying anti-GM1 antiserum appeared to attenuate LTP. Exogenous GM1 treatment not only antagonized LTP suppression caused by low Ca2+ (1.0 microM) in the perfusion medium, but also amplified LTP at high Ca2+ (5.0 microM) condition. Thus, GM1 may stabilize intracellular calcium levels to enhance synaptic potentiation.

Animals↗
PubMed1992

CRF increases protein phosphorylation and enhances retention performance in rats.

This study examines the roles of PKC and protein phosphorylation in the retention performance of a passive avoidance learning (PAL) task in rats. Results revealed that H7 injected into the dentate gyrus (DG) of the hippocampus impaired retention in a dose-dependent manner. Corticotropin-releasing factor (CRF) injected into the DG improved retention and this facilitation was antagonized by H7 pretreatment. CRF increased phosphorylation of five proteins, whereas H7 decreased phosphorylation in three of these proteins in both the cytosol and the membrane fractions of hippocampus. These effects were shown not to be associated with stress. These results demonstrate that CRF increased protein phosphorylation associated with enhanced retention of PAL task in rats.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Neonatal status in cesarean section under epidural anesthesia with supplementary oxygen.

Simple O2 mask has been used in patient under regional anesthesia for increasing the FiO2, especially in the aged and the pregnant. The relationships between maternal FiO2 and umbilical arterial (UA) and venous (UV) PO2, PCO2, pH, and neonatal Apgar score were studied in 45 patients receiving Cesarean section under epidural anesthesia. 2% xylocaine 18-20 ml with adrenaline 1:200,000 was used to attain the sensory level of T-4. Patients were allocated randomly into three groups. Group I, acting as a control group, breath only room air during the course of anesthesia. Group II was breathing through a simple face mask with an oxygen inflow of 6L/min. Group III was breathing oxygen with a flow rate of 10L/min through a simple face mask. UA and UV blood samples were collected separately at the time of delivery for blood gas analysis. The 1-min, and 5-min Apgar scores were recorded also. Mean values of the UA blood samples for the 3 groups (Gp. I, Gp. II and Gp. III respectively) were: PO2--16.50 mmHg, 20.20 mmHg and 19.50 mmHg; PCO2--49.20 mmHg, 48.10 mmHg and 50.3 mmHg; pH--7.31, 7.30 and 7.30. Mean values of the UV blood samples for the 3 groups (Gp. I, Gp. II and Gp. III respectively) were: PO2--28.6 mmHg, 36.9 mmHg and 36.5 mmHg; PCO2--38.20 mmHg, 38.80 mmHg and 40.40 mmHg; pH--7.36, 7.36 and 7.34. There was a significant increase in UA and UV PO2 when using a simple O2 mask (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[The relationship between weights of fetuses with autosomal trisomies and low maternal serum alpha-fetoprotein].

An association between low maternal serum alpha-fetoprotein (MSAFP) and fetal trisomy has now been thoroughly documented. The mechanisms resulting in low MSAFP are still unclear. In order to determine whether the low values of MSAFP in autosomal trisomies are associated with smaller fetal weights, we compared 11 fetuses with Down syndrome (trisomy 21), 4 with trisomy 18, with 45 normal fetuses. All of them are aborted in the second trimester of pregnancy. No significant difference in the weight distribution between fetuses with Down syndrome and control fetuses was found. In contrast, as compared with the control fetuses, fetuses with trisomy 18 had a significant lower weight distribution. The mean value of MSAFP was 0.72 +/- 0.26 MoM for those with Down syndrome and 0.51 +/- 0.33 MoM for fetuses with trisomy 18; both results being significantly lower than that of normal control (1.01 +/- 0.28). The mean value of amniotic fluid AFP was 0.63 +/- 0.23 MoM for fetuses with Down syndrome. This value was significantly lower than those of the fetuses with trisomy 18 and normal controls (1.02 +/- 0.09 and 1.02 +/- 0.30). A linear relationship between MSAFP and fetal weight was found in normal fetuses at a given gestational age but was not found in trisomy pregnancy. Fetal weight cannot be used to explain the reason for low MSAFP in Down syndrome pregnancy but may partially account for the lower levels noted in fetuses with trisomy 18.

Body Weight↗
PubMed1992

Meconium peritonitis-antenatal diagnosis by ultrasound.

Meconium peritonitis is usually the result of prenatal bowel obstruction with subsequent perforation, then the contents spread into the peritoneal cavity, which results in a sterile inflammatory reaction. The incidence ranges from 1/1500 to 1/2000, if without prenatal diagnosis and planned postnatal treatment, the mortality rate is as high as 62%. We describe three children, two with surgically, one with autoptically confirmed meconium peritonitis. All had abnormally prenatal ultrasonographic examinations. The first fetus showed a large 10 x 11 cm intra-abdominal mass with floating echogenic substances inside and with an echogenic rim. The second showed increased echogenicity with dilated bowel in abdominal cavity in one of the twin, and the third had an intra-abdominal cyst with several echogenic bands inside, fetal ascites was also noted. It is remarkable that the ultrasonographic findings were different in the three children. Two of the three children survived postoperation, one died 3 hours later after induction out at 31 weeks of gestational age due to multiple congenital anomalies.

Adult↗
PubMed1991

Regional GABA-stimulated chloride uptake in amygdala kindled rats.

gamma-Aminobutyric acid (GABA)-stimulated 36chloride (Cl-) influx into membrane vesicles derived from cerebral cortex, hippocampus, cerebellum and midbrain/brainstem was evaluated in naive rats and amygdala or sham kindled rats. GABA-stimulated 36Cl- uptake was greatest in cortex and hippocampus of naive rats. One week after amygdala kindling, 10 microM GABA-stimulated 36Cl- influx was significantly reduced in each brain region, except midbrain/brainstem, indicating a regional variation in impaired GABAergic function. Midazolam potentiation of GABA-mediated Cl- flux showed a regional variation. The effect of midazolam in kindled rats indicated either an increase in efficiency of GABA/benzodiazepine coupling in areas of reduced GABA function or its ability to restore Cl- channel function to the pre-kindled state.

Amygdala↗
PubMed1991

Differential tolerance to the antipentylenetetrazol activity of benzodiazepines in flurazepam-treated rats.

Rats were treated for one week with flurazepam (FZP). After an additional two days with no treatment, each rat was injected with one of seven benzodiazepines (BZs). Several different doses of each BZ were evaluated. Ten min later, 100 mg/kg pentylenetetrazol (PTZ) was injected, IP, and convulsive activity was recorded. Rats treated for a week with FZP were tolerant to ataxia induced by each of the seven BZs tested. There was a dose-dependent anti-PTZ effect for each BZ. Whether or not tolerance to the anti-PTZ effect was found depended on the particular BZ used. Tolerance was found for four of the drugs: diazepam, clobazam, flurazepam and desalkylflurazepam. However, no tolerance was found to the anti-PTZ actions of midazolam, triazolam or clonazepam. Brain BZ levels were measured by the ability of brain extracts to displace specifically bound [3H]flunitrazepam in vitro. There was no significant effect of one week of flurazepam treatment. It was proposed that differences among BZs in their interactions with receptors allowed some to circumvent the mechanism responsible for tolerance to the anti-PTZ effect.

Animals↗
PubMed1991

6-Pentadecylsalicylic acid: an antithrombin component isolated from the stem of Rhus semialata var. roxburghii.

Bioassay-directed fractionation of the n-hexane extract of the stem of Rhus semialata Murr. var. roxburghii DC (Anacardiaceae) has led to the isolation of 6-pentadecylsalicylic acid. It showed antithrombin activity at 50 micrograms/ml in the amidolytic method. It also prolonged the clotting time in a dose-dependent manner in the clotting assay of thrombin-fibrinogen interaction.

Amino Acid Sequence↗
PubMed1991

The value of cordocentesis in management of patients with severe preeclampsia.

Severe preeclampsia affects placental function and causes fetal compromise. It is necessary to deliver the fetus at an appropriate time in order to minimize fetal mortality and morbidity. Cordocentesis was performed in 9 patients with severe preeclampsia (group 1) and 10 patients with other pregnancy complications (group 2). Intrauterine growth retardation occurred in 5 patients in group 1 and in only one patient in group 2. Blood gas parameters including pH, pO2 and O2 saturation were significantly lower for group 1, while pCO2 was significantly higher, as compared to group 2. For patients in group 1, non-invasive fetal surveillance successfully identified 5 patients with fetal compromise, who required immediate termination of pregnancy. All 5 of these patients had abnormal fetal blood gas analyses by cordocentesis. Fetal blood gas analysis was abnormal in 2 additional fetuses among the remaining 4 patients who exhibited normal findings by non-invasive methods of fetal surveillance. These results suggest that cordocentesis is useful in identifying fetal compromise (fetal hypoxia/acidosis) prior to the onset of labor in high-risk patients, such as preeclampsia associated with intrauterine growth retardation.

Acidosis↗
PubMed1991

Pregnancy outcome in patients undergoing long-term hemodialysis.

Three uremic patients receiving hemodialysis for more than 5 years became pregnant and proceeded to the third trimester. A variety of complications were noted, including threatened abortion, vanished twin, preterm premature rupture of membranes, polyhydramnios, intra-uterine fetal death, intra-uterine growth retardation, premature labor and hypertension. Two of these 3 mothers gave birth to healthy babies under the management of the high-risk pregnancy team.

Adult↗
PubMed1991

Analysis of birth weight and gestational age in Taiwan.

Appropriate interpretation of monitored fetal growth throughout pregnancy in individual patients and populations is dependent upon the availability of adequate standards. Previously published standards either were based on small samples, data decades old or were characteristic of foreign subpopulations. We have reviewed the data on a series of 46,575 singleton live births at Chang Gung Memorial Hospital from 1979 to 1989. The ratio of males to females was 1.08. The fetal growth pattern in the third trimester of pregnancy approximates a sigmoid curve. Fetal growth was most rapid from the 32nd to the 37th week of gestation with an average increase of 240 g per week. The birth weight declined beyond 42 weeks' gestation. There were significantly greater weight gains amongst male fetuses as compared to female fetuses from the 34th to the 42nd week of gestation. The mean birth weight recorded at 40 weeks' gestation in male and female newborns was 3,381 g and 3,262 g, respectively. Comparing the birth weight of term pregnancies using our data, with those of a previous, two-decade old report (1945-1967) by Chen, we found that birth weight were slightly higher in this study. The derived fetal growth curves are useful for clinical, public health, and investigational purposes.

Adult↗
PubMed1991

Effects of cholinergic depletion by medial septal area lesions on synaptic responses in CA1 area of hippocampal slices.

In order to examine the influence of acetylcholine on synaptic transmission and synaptic enhancement after tetanic stimulation in the hippocampal CA1 area, a cholinergic depletion model was used. It was found that bilateral lesions of the medial septal area (MSA) by microinjection of kainic acid produced a dramatic reduction of acetylcholinesterase-positive (AChE(+)) fibers, presumably cholinergic, in most of hippocampal areas. Electrophysiologically, MSA lesions caused a decrease of excitatory postsynaptic potential (EPSP) slope and population spike (PS) amplitude at a given stimulus intensity in the hippocampal CA1 area in vitro. Although hippocampal synapses could still be potentiated after tetanic stimulation, a faster decay of synaptic enhancement was found in slices from lesioned animals. Since no apparent tissue damage or ultrastructural abnormality was found in the hippocampal CA1 area, except the loss of cholinergic fibers, after MSA lesions, it was speculated that reduction in synaptic transmission and enhancement may be due to weakening of cholinergic amplification on synaptic responses mediated by excitatory amino acids.

Acetylcholinesterase↗
PubMed1991

Changing trends of forceps delivery in Chang Gung Memorial Hospital.

Two hundred and fifty-five patients underwent forceps deliveries in Chang Gung Memorial Hospital from January 1, 1985 to June 30, 1990. There was neither maternal nor perinatal mortality related to this procedure during this period; and the perinatal outcome was good without sequela. In the past three years, cesarean section took the place of forceps delivery in some cases with acute fetal distress and malposition. As a result, maternal problems became the most common indication for forceps delivery during that period. Fourth degree laceration of the perineum was the major maternal complication, occurring in 22.4% of total forceps deliveries. Postpartum voiding problems continued to be another complication after forceps delivery, accounting for 7.0%. Either fourth degree laceration of the perineum or postpartum voiding difficulty could be prevented to a certain extent if the forceps were handled delicately in an experienced hand and there was early diagnosis with prompt management of voiding dysfunction.

Adult↗