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T Chung

Publications and source records attributed to T Chung.

At least 55 records · Page 3Linked to original sources
PubMed1997

ATP-dependent choline phosphate-induced mitogenesis in fibroblasts involves activation of pp70 S6 kinase and phosphatidylinositol 3'-kinase through an extracellular site. Synergistic mitogenic effects of choline phosphate and sphingosine 1-phosphate.

In serum-starved NIH 3T3 clone 7 fibroblasts, choline phosphate (ChoP) (0.5-1 mM) and insulin synergistically stimulate DNA synthesis. Here we report that ATP also greatly enhanced the mitogenic effects of ChoP (0.1-1 mM) both in the absence and presence of insulin; maximal potentiating effects required 50-100 microM ATP. The co-mitogenic effects of ATP were mimicked by adenosine 5'-O-(3-thiotriphosphate), adenosine 5'-O-(2-thiodiphosphate), ADP, and UTP, but not by AMP or adenosine, indicating the mediatory role of a purinergic P2 receptor. Externally added ChoP acted on DNA synthesis without its detectable uptake into fibroblasts, indicating that ChoP can be a mitogen only if it is released from cells. Extracellular ATP (10-100 microM) induced extensive release of ChoP from fibroblasts. ChoP had negligible effects, even in the presence of ATP or insulin, on the activity state of p42/p44 mitogen-activated protein kinases, while in combination these agents stimulated the activity of phosphatidylinositol 3'-kinase (PI 3'-kinase). Expression of a dominant negative mutant of the p85 subunit of PI 3'-kinase or treatments with the PI 3'-kinase inhibitor wortmannin only partially (approximately 40-50%) reduced the combined effects of ChoP, ATP, and insulin on DNA synthesis; in contrast, the pp70 S6 kinase inhibitor rapamycin almost completely inhibited these effects. ATP and insulin also potentiated, while rapamycin strongly inhibited, the mitogenic effects of sphingosine 1-phosphate (S1P). Furthermore, even maximally effective concentrations of ChoP and S1P synergistically stimulated DNA synthesis. The results indicate that in the presence of extracellular ATP and/or S1P, ChoP induces mitogenesis through an extracellular site by mechanisms involving the activation of pp70 S6 kinase and, to a lesser extent, PI 3'-kinase.

3T3 Cells↗
PubMed1997

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line.

OBJECTIVE: To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour. DESIGN: Retrospective observational study. METHODS: Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor. The computerised algorithm for the baseline estimation was developed for intrapartum applications and is based on averaging modal fetal heart rate values. Evaluation was carried out on sixty cardiotocographic recordings by 12 experts and by the computer. These estimates were compared with those obtained from the computerised system using paired differences and intraclass correlation. RESULTS: The study showed that it is possible to produce a low frequency line from data obtained from intrapartum records. The system could not estimate the low frequency line in four records, whereas experts were also unable to estimate between one and seven tracings. The 95% CI for the paired differences between computer and experts was -12 to 15 bpm, whereas between the experts this was -10 to 10. With the exception of one expert, there was a high concordance between experts and between computer and experts (intraclass correlation > 0.9). CONCLUSIONS: The performance of this computerised algorithm cannot be distinguished from that of experienced clinicians. There were no significant differences between baseline values obtained by the computerised algorithm and those by the clinicians.

Algorithms↗
PubMed1997

The relation of neuropsychological measures to levels of cognitive functioning in elderly individuals: a discriminant analysis approach.

This study addresses the question of which tests in a comprehensive neuropsychologicaI test battery best discriminate normal, mildly, and moderate to severely cognitiveIy impaired older participants. Sixty-six geriatric participants were administered a battery of neuropsychological tests as part of an outpatient geriatric clinic evaluation. A discriminant analysis procedure using a consensus rating of global cognitive impairment as the grouping variable was employed to analyze the data. From 15 neuropsychological test measures, five representing the domains of learning and memory, visuospatial and executive functioning were identified as the best predictors of level of cognitive impairment. Findings demonstrate the utility of discriminant function analysis (DFA) procedures for developing reduced-length cognitive batteries that accurately classify participants in terms of levels of cognitive impairment and identify mild dysfunction in participants at risk of cognitive impairment. Further cross-validation studies are needed to confirm the utility of these more circumscribed batteries.

Journal Article↗
PubMed1997

Physiological alcohol dependence as a "specifier" of risk for medical problems and relapse liability in DSM-IV.

OBJECTIVE: This study tested the ability of DSM-IV physiological alcohol dependence to predict multiple indices of medical problems and relapse behavior. It also tested the ability of three additional variables--DSM-IV nonphysiological dependence, an alternative dichotomous criterion for coding physiological dependence and a dimensional measure of physiological dependence--to predict medical problems and relapse behavior in alcoholism. METHOD: A heterogeneous group of 365 patients was recruited from eight addictions treatment programs in the northeastern United States. A multidimensional assessment battery able to diagnose the presence of physiological dependence according to each of three systems--the criteria of DSM-IV, alternative dichotomous criteria and a dimensional scale-- was administered about 2 weeks after admission, and 241 subjects were reinterviewed 6 months later. The three systems were compared for their ability to predict a variety of external measures of medical complications and relapse liability. RESULTS: Physiological alcohol dependence as diagnosed by DSM-IV bore no relationship to either risk for medical problems or relapse behavior. Further analyses showed that this failure was due to operational problems of physiological dependence in DSM-IV, rather than to a lack of conceptual merit for physiological dependence per se as a course specifier. Use of alternative criteria for coding physiological dependence which are difficult and less internally consistent, and use of a dimensional measure, found improved relationships with the external validators. CONCLUSIONS: Contrary to early reports, physiological dependence can serve as a course specifier for alcohol problems, but must be more sensitively scaled than it was in DSM-IV. Tests of alternative options suggest that a multistage criterion to replace DSM-IV's dichotomous criterion is the best remedy.

Adolescent↗
PubMed1997

Urinary retention in the post-partum period. The relationship between obstetric factors and the post-partum post-void residual bladder volume.

OBJECTIVE: The three objectives of this study are: to investigate the incidence of post-partum urinary retention after vaginal delivery, to investigate the relationship between various obstetric parameters and the post-partum post-void residual bladder volume and to study the natural progression of the post-void residual bladder volume in patients with covert post-partum urinary retention. METHODS: Women who had a vaginal delivery (n = 691) in a teaching hospital during a 2-month period were studied. They were classified into three groups: normal patients, those with overt urinary retention, and covert urinary retention. Their day 1 post-partum post-void residual bladder volume were recorded and analyzed with respect to the obstetric parameters. Patients with covert retention were followed up daily with ultrasound to monitor their post-void residual volume. RESULTS: The incidences of overt and covert retention in our unit were 4.9% and 9.7%, respectively. The overall incidence of post-partum urinary retention after vaginal delivery was 14.6%. The duration of the first and second stages of labor were significantly associated with the post-partum post-void residual bladder volume. In all patients with covert retention, their post-void residual volume returned to normal within 4 days. CONCLUSION: Post-partum urinary retention is a common phenomenon that may be related to the process of parturition. Covert retention is a self-limiting phenomenon and specific treatment is unnecessary.

Adult↗
PubMed1997

A medical approach to management of spontaneous abortion using misoprostol. Extending misoprostol treatment to a maximum of 48 hours can further improve evacuation of retained products of conception in spontaneous abortion.

BACKGROUND: To compare a 48 hour non surgical policy in the management of spontaneous abortion with a policy of routine, universal uterine curettage. METHODS: A prospective, observational study on 354 women admitted to hospital with spontaneous abortion. Of these, 225 who had retained products of conception were treated with misoprostol for up to 48 hours after 101 were excluded because they had an empty uterus on transvaginal scan (TVS) and another 28 women because they were unsuitable for conservative management. Follow-up was conducted over a 3 week period to assess morbidity. A reference group of 137 women, all of whom had an evacuation of retained products of conception (ERPC) as a routine after they had a TVS documenting retained products of conception (POCs), was used for comparison. RESULTS: Evacuation of the uterus occurred within 24 hours in 107 women and in 148 at 48 hours after misoprostol treatment was started. There were three uterine curettages up to 14 days after discharge from hospital for persistent bleeding and two cases of pelvic infection. An ectopic pregnancy was diagnosed at follow-up in one woman. In the reference group, there were nine women who had complications, four requiring another ERPC and five had infection, an overall complication rate of 6.6% in the reference group and 1.7% in the protocol treatment group. CONCLUSION: A 48 hour regimen using transvaginal ultrasound and misoprostol for the management of spontaneous abortion was successful in avoiding surgery in 249 out of a possible 354 (70.6%) women with spontaneous abortion, with a low rate of subsequent morbidity.

Abortifacient Agents, Nonsteroidal↗
PubMed1996

Protein kinase Calpha is a major mediator of the stimulatory effect of phorbol ester on phospholipase D-mediated hydrolysis of phosphatidylethanolamine.

Stimulation of phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PtdCho) by phorbol 12-myristate 13-acetate (PMA) has been shown to be mediated by the alpha- and betaI-isoforms of protein kinase C (PKC). To determine the role of various PKC isozymes in the regulation of PLD-mediated phosphatidylethanolamine (PtdEtn) hydrolysis, MCF-7 human breast carcinoma cells overexpressing the alpha- and theta-isoforms, and R6 rat fibroblasts overexpressing the alpha-, betaI-, and epsilon-isoforms were used. In the vector control MCF-7 cells, which contain low levels of PKC-alpha, PMA (100 nM) had only small effects on the hydrolysis of PtdEtn (1.1-1.35-fold) and PtdCho (1.15-1.6-fold). Stable expression of PKC-alpha in MCF-7 cells, which was accompanied by increased levels of the betaI- and theta-isoforms as well, greatly enhanced both PMA-induced PLD-mediated formation of phosphatidylethanol (approximately 5-fold) and the hydrolysis of PtdEtn (2.5-2.9-fold) and PtdCho (5.5-7.2-fold). The effects of PMA on the hydrolysis of PtdEtn (and PtdCho) in MCF-7/PKC-alpha cells were significantly inhibited by 0.5-3 microM concentrations of Gö 6976, a selective inhibitor of the conventional PKC subfamily. Stable expression of PKC-alpha in R6 fibroblasts enhanced, at a shorter (10 min) incubation time, the effects of PMA on the hydrolysis of both PtdEtn and, to a lesser extent, PtdCho. In contrast, stable expression of PKC-betaI in R6 fibroblasts, which originally did not contain this enzyme, enhanced the effects of PMA only on PtdCho, but not PtdEtn, hydrolysis. Overexpression of either PKC-theta in MCF-7 cells or PKC-epsilon in R6 and NIH 3T3 fibroblasts had no detectable effects on PMA-induced hydrolysis of PtdEtn. Collectively, the results suggest that PKC-alpha has a major role in the mediation of phorbol ester action on PtdEtn hydrolysis, while PtdCho hydrolysis may be regulated by both the alpha and betaI isoforms.

Animals↗
PubMed1996

Effect of oral estradiol on Lp(a) and other lipoproteins in postmenopausal women. A randomized, double-blind, placebo-controlled, crossover study.

BACKGROUND: Lp(a) lipoprotein level is an independent risk factor for premature coronary artery disease and cerebrovascular accident. Concentrations of this lipoprotein tend to increase after menopause. OBJECTIVE: To determine whether oral estrogen was effective in lowering concentrations of Lp(a) lipoprotein in postmenopausal women. METHODS: A double-blind, placebo-controlled, cross-over study was conducted during a 12-month period in 100 postmenopausal women who had undergone hysterectomy. They were randomized into two groups: group 1 received oral estradiol, 2 mg/d, for the first 6 months and placebo for the second, and group 2 received these treatments in the reverse order. After completion of the crossover study, the effect of prolonged administration of oral estradiol was examined by placing all patients on active treatment and repeating the lipoprotein measurements approximately 12 months later. RESULTS: No significant differences were noted between the two groups at the commencement of the study (median concentration of Lp[a] lipoprotein, 10.78 mg/dL [range, 2.2 to 108.5 mg/dL] in group 1 and 12.74 mg/dL [range, 0.8 to 98.1 mg/dL] in group 2). Crossover analysis showed a 9.62% reduction in values of Lp(a) lipoprotein with estradiol treatment compared with placebo during 12 months of treatment (P < .001). With prolonged treatment, the median concentration of Lp(a) lipoprotein for those in group 1 decreased from 8.12 mg/dL (range, 1.05 to 57.4 mg/dL) to 5.77 mg/dL (range, 0.84 to 75.39 mg/dL) (P < .001). In group 2, the median concentration decreased from 8.19 mg/dL (range, 2.52 to 99.82 mg/dL) to 7.07 mg/dL (range, 0.70 to 48.79 mg/dL), but this difference was not significant (P = .63). CONCLUSIONS: The results of this study confirm the beneficial effect of oral estradiol on the basic lipoprotein pattern and demonstrate that this treatment is effective in reducing concentrations of Lp(a) lipoprotein in postmenopausal women.

Administration, Oral↗
PubMed1996

Choline phosphate and phorbol ester potentiate the mitogenic effect of insulin by competitive mechanisms in NIH 3T3 fibroblasts.

Treatments of serum-starved NIH 3T3 fibroblasts with either 100 nM phorbol-12-myristate 13-acetate (PMA) or 1 mM choline phosphate (ChoP) greatly enhanced, in a mutually inhibitory manner, the stimulatory effect of insulin on DNA synthesis. Wortmannin and GF 109203X, inhibitors of phosphatidylinositol 3'-kinase and protein kinase C, respectively, inhibited only the combined mitogenic effects of PMA and insulin, but not that of ChoP and insulin. In the presence of 0.5% fetal calf serum, both ChoP and insulin, but not PMA, retained their mitogenic activities, while PMA abolished the stimulatory effect of insulin on DNA synthesis. The results indicate that PMA can both enhance and inhibit the mitogenic action of insulin, depending on the presence of serum factors and ChoP.

3T3 Cells↗
PubMed1996

Musculoskeletal magnetic resonance imaging: how we do it.

This paper reviews the techniques that we employ to perform musculoskeletal magnetic resonance imaging in the pediatric patient. We examine the procedures for preparation and screening of the patient and the protocols for sedation. The selection of imaging coils and sequences for the evaluation of the pediatric musculoskeletal system is also addressed, followed by a summary of scanning protocols.

Bone Diseases↗
PubMed1996

MR imaging of hepatic hemangiomas of infancy and changes seen with interferon alpha-2a treatment.

The purpose of this study was to describe the appearance on magnetic resonance (MR) imaging of hepatic hemangioma, and how the appearance changes in infants who have received interferon alpha-2a (IFN) treatment. We retrospectively studied 16 MR examinations in seven infants (mean age 3.2 months; range 5 days to 13 months) who were symptomatic with hepatic hemangiomas. Five of these seven patients had MR examinations both before and after treatment with IFN. In six of the seven patients, the hepatic hemangiomas were multicentric; they were usually discrete, well-defined nodules, best seen on T2-weighted images as high intensity lesions. One patient had a large solitary heterogeneous lesion. They all exhibited fast flow (seen as flow voids on spin-echo images and high signal intensity structures on gradient-recalled echo images) and enlarged hepatic arteries and veins. There was enlargement of the proximal abdominal aorta with distal tapering. Treatment was followed by accelerated regression of the hemangiomas in size and number and variable shrinkage of the enlarged vessels. As the tumor nodules regressed, they were replaced by normal-appearing hepatic parenchyma; neither fat nor fibrosis was detected by MR imaging.

Female↗
PubMed1996

Transrectal drainage of deep pelvic abscesses in children using a combined transrectal sonographic and fluoroscopic guidance.

The authors review their experience with transrectal drainage of pelvic abscesses in seven children and adolescents (6-16 years old). Initial access was guided by transrectal ultrasound with an endovaginal transducer followed by fluoroscopy for placement of self-retaining catheters (8.5-10 F) using the Seldinger technique. All abscesses were successfully drained without complications. A transrectal catheter was well tolerated by most patients without spontaneous dislodgment. Catheters were removed after an average of 4 days (range 3-7 days). Transrectal drainage of pelvic abscess with transrectal sonographic and fluoroscopic guidance seems to be a safe and effective procedure in children.

Abscess↗
PubMed1996

Yeast thiol-dependent protector protein expression enhances the resistance of Escherichia coli to hydrogen peroxide.

A soluble protein from Saccharomyces cerevisiae specifically provides protection against a thiol-containing oxidation system but not against an oxidation system without thiol. This 25-kDa protein was thus named thiol-dependent protector protein (TPP). The role of TPP in the cellular defense against oxidative stress was investigated in Escherichia coli containing an expression vector with a yeast genomic DNA fragment that encodes TPP (strain YP) and mutants in which the catalytically essential amino acid cysteine (Cys-47) has been replaced with alanine (strain YPC47A) or tryptophan (Trp-82) has been replaced with phenylalanine (strain YPW82F) by a site directed mutagenesis. There was a distinct difference between these three strains in regards to growth inhibition kinetics, viability, modulation of activities of superoxide dismutase and catalase, and the accumulation of oxidized proteins. These results suggest that TPP may play a direct role in the cellular defense against oxidative stress by functioning as an antioxidant protein.

Alanine↗
PubMed1996

Cervical ripening before induction of labour in patients with an unfavourable cervix: a comparative randomized study of the Atad Ripener Device, prostaglandin E2 vaginal pessary, and prostaglandin E2 intracervical gel.

One hundred and nineteen women with singleton pregnancy and cephalic presentation requiring induction of labour in the presence of an unfavourable cervix (Bishop score < or = 4) were studied. Five patients were excluded because of failure to comply with the protocol. Cervical ripening was carried out using 3 different methods; 36 used the Atad Ripener Device, 39 received 0.5 mg PGE2 intracervical gel and 39 received at least one 3 mg PGE2 intravaginal pessary. There were no differences in the demographic characteristics and the indications for induction. Five patients developed complications during the ripening period necessitating intervention; 3 required emergency Caesarean section and 2 delivered vaginally. Although statistically there were no differences among the 3 methods of cervical ripening, the power of the study is probably not large enough to show the differences. The PGE2 pessary appears to be more effective with 68% of patients either going into labour during cervical ripening or succeeding in the cervical ripening compared to around 50% in the Atad and PGE2 gel groups. The vaginal delivery rate was 87.2% in the pessary group compared to 72.2% in the Atad group and 84.6% in the gel group. The duration of labour was also shorter in the pessary group with 73.5% delivered within 24 hours compared to 57.7% in the Atad group and 57.6% in the gel group. Although the results of the Atad device seem to be inferior, the risk of uterine hyperstimulation from the use of the device is probably lower than that of the PGE2 and may therefore be preferable in women with fetuses at high risk of fetal hypoxia.

Adult↗
PubMed1996

Genital prolapse: a legacy of the West?

A retrospective study was undertaken to determine if there has been a change in the incidence of genital prolapse and urinary stress incontinence in Chinese women in Hong Kong. The medical records of 2,312 consecutive patients admitted for major gynaecological surgery for benign conditions in 5 out of 7 major public teaching hospitals in Hong Kong for the calendar year of 1993 were reviewed by way of an audit of all gynaecological operations performed in these hospitals. A total of 578 cases (25%) were identified as having genital prolapse and or urinary problems.

Female↗