Biomedical subjects

K C Yeung

Publications and source records attributed to K C Yeung.

9 recordsLinked to original sources

PubMed1996

Oral misoprostol versus mifepristone for cervical dilatation before vacuum aspiration in first trimester nulliparous pregnancy: a double blind prospective randomised study.

OBJECTIVE: To compare the effectiveness of oral misoprostol and mifepristone for cervical priming before first trimester termination of nulliparous pregnancy. DESIGN: Prospective double blind randomised study. SETTING: Department of Obstetrics and Gynaecology, University of Hong Kong. PARTICIPANTS: One hundred nulliparous women undergoing termination of pregnancy between 8 and 12 weeks of gestation were recruited for this prospective randomised trial. The women were allocated to either the oral misoprostol or mifepristone group. Subjects in misoprostol group were given placebo and misoprostol 400 micrograms 36 h and 12 h respectively before vacuum aspiration. Subjects in mifepristone group were given 200 mg mifepristone and placebo 36 h and 12 h respectively prior to operation. MAIN OUTCOME MEASURES: Baseline pre-operative cervical dilatation, the incidence of side-effects, the amount of blood loss and duration of procedure. RESULTS: There were no significant differences in the baseline cervical dilatation, incidence of side-effects, amount of blood loss and duration of procedure. CONCLUSIONS: Misoprostol and mifepristone are of similar effectiveness for cervical priming prior to vacuum aspiration in nulliparous women. Misoprostol has additional advantages of being widely available and inexpensive.

Abortifacient Agents, Nonsteroidal↗

PubMed1995

Oral misoprostol versus vaginal gemeprost for cervical dilatation prior to vacuum aspiration in women in the sixth to twelfth week of gestation.

The effectiveness of oral misoprostol versus vaginal gemeprost for cervical dilatation prior to vacuum aspiration was compared in women in the 6th to 12th week of pregnancy. Sixty-four nulliparous women requesting termination of pregnancy between 6th to 12th weeks of gestation were randomized to receive either 400 micrograms misoprostol orally or 1 mg vaginal gemeprost at 12 hr or 3 hr prior to vacuum aspiration, respectively. The cervical dilatation at vacuum aspiration, the ease of the subsequent surgical procedure, and the incidence of complications and side effects were compared between these two methods of cervical priming. The median cervical dilatation at vacuum aspiration in the misoprostol group was significantly greater than that in the gemeprost group (8.0 mm versus 7.0 mm, p < 0.02). Preoperative side effects were significantly less frequent in the misoprostol group (p < 0.01). The ease of dilatation assessed subjectively by the operating surgeons was also improved significantly in the misoprostol group (p < 0.01). However, the duration of operation and blood loss were similar in both groups. Since misoprostol is also much cheaper and more convenient to use, we conclude that oral misoprostol is better than vaginal gemeprost for cervical dilatation prior to vacuum aspiration in first trimester pregnancy.

Abortifacient Agents, Nonsteroidal↗

PubMed1995

Temperature and dimensional changes in the two-stage processing technique for complete dentures.

OBJECTIVES: This study concerned the temperature and linear dimensional change of heat-cured acrylic resin in the two-stage processing technique for complete dentures. METHODS: Thermocouples were incorporated in the acrylic resin for recording temperatures. Measurements between reference marks were made by a high-resolution digital measuring microscope. RESULTS: No increase in temperature associated with the exothermic nature of the polymerization reaction was recorded. The temperature of the resin followed the waterbath temperature closely. The temperatures recorded at various regions were in phase with each other. The total linear shrinkage of the base after two processing cycles was less than 1% and compares favourably with studies on the single-stage processing technique. CONCLUSIONS: Temperature differential is excluded as a reason for the warpage of dentures. The dimensional changes of the denture base resulting from the two-stage processing technique cannot be considered to be of any clinical significance.

Acrylic Resins↗

PubMed1995

Out-of-hospital cardiac arrest: two and a half years experience of an accident and emergency department in Hong Kong.

The results are presented of 2 1/2 years of experience of patients with out-of-hospital cardiac arrests who were resuscitated in an accident and emergency department (A&E) attached to an acute district hospital in Hong Kong. Out of 263 cases of out-of-hospital cardiac arrest as a result of a variety of causes only seven patients survived (3%) and among the 135 patients with cardiac aetiology only four survived (3%). Ways to improve the outcome for out-of-hospital cardiac arrest are discussed.

Adult↗

PubMed1994

Structure-function analysis of the TBP-binding protein Dr1 reveals a mechanism for repression of class II gene transcription.

Dr1, a repressor of class II genes, regulates transcription by a novel mechanism. Biochemical analyses reveal that Dr1 directly interacts with the multiprotein TFIID complex. By use of the yeast two-hybrid system, we demonstrate that the association of Dr1 with the TATA-binding protein (TBP) subunit of TFIID occurs in vivo. In addition, Dr1 can repress transcription from TATA-containing as well as TATA-less promoters in transient transfection assays. Importantly, Dr1-mediated repression can be reversed by overexpression of TBP in vivo. By use of diverse approaches, we mapped two distinct domains in Dr1 required for repression. One domain is essential for the Dr1-TBP interaction, and the second is rich in alanine residues. The TBP-binding domain of Dr1 cannot be replaced by a heterologous DNA-binding domain in mediating repression. We demonstrate that some, but not all, transcriptional activators can reverse Dr1-mediated repression in vivo.

Amino Acid Sequence↗

PubMed1993

Mutations of the human cytomegalovirus immediate-early 2 protein defines regions and amino acid motifs important in transactivation of transcription from the HIV-1 LTR promoter.

The human cytomegalovirus (HCMV) immediate-early two (IE2) protein of 579 amino acids significantly activates expression from the human immunodeficiency virus (HIV) long terminal repeat (LTR) promoter. Using a proviral HIV-1 genome with a mutated tat gene we demonstrate that the IE2 protein effects an increase in the steady-state level of viral RNA similar to a level as from a wild-type proviral genome. The regions of the HCMV IE2 protein required for transactivation of the HIV-1 LTR promoter were analyzed by mutagenizing the IE2 gene and determining the activity of the mutant protein in human fibroblast cells. The region between amino acids 169 and 194 is required to transactivate the HIV-1 LTR promoter, although we have previously shown that this region is not required to activate a representative HCMV early promoter (C. L. Malone, et al., J. Virol. 64, 1498, (1990)). A region downstream of amino acid 290, which is required to activate a representative HCMV early promoter, is also required to activate the HIV-1 LTR promoter. Three types of mutations within this region were shown to greatly decrease IE2 activity: (1) amino acid substitutions of the cysteine or histidine residues in a putative zinc finger motif between amino acids 428 and 452; (2) substitution of the acidic charged residues between amino acids 558 and 561; (3) substitution of the two prolines at residues 556 and 557 immediately upstream of these acidic residues. Substitution of the other acidic residues near the carboxyl terminus also diminished transactivation by IE2. These data indicate that acidic amino acids and the secondary structure in the carboxyl end of the IE2 protein have an important role in transactivation of the HIV-1 LTR promoter. The other regions of the IE2 protein required for transactivation of the HIV-1 LTR are discussed.

Amino Acid Sequence↗

PubMed1991

Differences in the capacity of two herpes simplex virus isolates to spread from eye to brain map to 1610 base pairs of DNA found in the gene for DNA polymerase.

A intertypic recombinant, designated HSV-R(D1), had previously been generated from non-neuroinvasive HSV-2(186) and neuroinvasive HSV-1(17). Although the recombinant contained less than 2% of the HSV-1 genome, it retained the neuroinvasive phenotype. The nucleotide sequences responsible for the neuroinvasiveness of HSV-R(D1) were previously mapped to a 3.0 kb segment of DNA located within the DNA polymerase gene (mu 0.414 to 0.430) via marker rescue experiments. We have now sequenced this region and compared our results to the published nucleotide sequence of the HSV-1(17) and HSV-2(186) DNA polymerase genes. It was found that the 3.0 kb HSV-R(D1) DNA fragment consisted entirely of HSV-2(186) nucleotide sequences except for the presence of 1610 bp of HSV-1(17) DNA. The 1610 bp of HSV-1 DNA coded for a 536 amino acid (AA) region which were located between AA 254 and 790 of the DNA polymerase enzyme. Comparison of the 536 AA sequence of neuroinvasive HSV-1(17) with the homologous area of the non-neuroinvasive HSV-2(186) DNA polymerase indicated that the two polymerases differed at 56 AA positions. In addition, this area of the HSV-1(17) DNA polymerase was 5 AA acids shorter than the HSV-2(186) DNA polymerase. Specific amino acid changes that might account for the neuroinvasive phenotype of HSV-R(D1) are discussed.

Amino Acid Sequence↗

PubMed1990

Nucleotide sequences responsible for the inability of a herpes simplex virus type 2 strain to grow in human lymphocytes are identical to those responsible for its inability to grow in mouse tissues following ocular infection.

A study was undertaken to determine whether genes associated with herpes simplex virus (HSV) neuroinvasiveness in mice influence the growth of HSV in man, the virus's natural host. HSV-2(186), a nonneuroinvasive HSV strain, was found to replicate poorly (less than 3-fold) in cultures of phytohemagglutinin (PHA) stimulated human peripheral blood mononuclear cells (PBMC). In contrast, seven other HSV strains all multiplied 40- to 100-fold. The paucity of HSV-2(186) growth in PBMC was not due to a failure of this strain to grow in primary human cells because high titers (greater than 10(8) PFU/ml) were obtained following infection of human foreskin fibroblasts. The genetic basis for the deficient growth was analyzed by marker rescue experiments. Recombinant HSV-2 strains were generated in marker rescue experiments utilizing HSV-2(186) DNA and plasmids containing a cloned DNA polymerase gene isolated from a neuroinvasive HSV strain possessing the capacity to replicate in human PBMC. Progeny which rescued DNA from the cloned HSV DNA polymerase gene replicated 40- to 100-fold in PHA-stimulated PBMC. Moreover, unlike the HSV-2(186) parent, HSV-2(186) isolates possessing rescued DNA grew well in the eye, trigeminal ganglion, and brain of mice and induced fatal encephalitis. The results indicate that nucleotide sequences responsible for increasing the capacity of HSV-2(186) to grow in PBMC of man are identical to those responsible for increasing the capacity of this strain to grow in mouse tissues and to spread from the eye to the brain.

Adult↗

PubMed1988

Genomic location of bovid herpesvirus type 2 nucleotide sequences homologous to five herpes simplex virus type 1 genes.

The location of nucleotide sequences within the bovid herpesvirus 1 (BHV-2) genome homologous to herpes simplex virus 1 (HSV-1) DNA were investigated. BHV-2 DNA was digested with restriction endonucleases and blotted to nitrocellulose paper. The blots were then probed with plasmids containing HSV-1 genes for thymidine kinase (TK), the major DNA binding protein (ICP8), the major capsid protein (VP5) and genes for HSV-1 glycoproteins gB, gD, and gC. Except for HSV-1 gC, each HSV-1 gene tested hybridized to BHV-2 nucleotide sequences that were located either on both sides of a restriction endonuclease cleavage site, within a small restriction endonuclease fragment, or to an area common to two overlapping restriction fragments. Thus, we were able to localize BHV-2 nucleotide sequences homologous to the HSV-1 ICP8 gene between 0.38 and 0.41 map units (m.u.), and BHV-2 nucleotide sequences homologous to the HSV-1 VP5 gene between 0.24 and 0.27 m.u. In addition, BHV-2 nucleotide sequences homologous to HSV-1 genes for TK, gB and gD were found to lie on both sides of restriction endonuclease cleavage sites at 0.30, 0.35, and 0.94 m.u., respectively.

Base Sequence↗