Biomedical subjects

H S Liu

Publications and source records attributed to H S Liu.

At least 55 records · Page 3Linked to original sources

PubMed1998

Expression of CTLA-4 molecule in peripheral blood T lymphocytes from patients with systemic lupus erythematosus.

CTLA-4 is a cell surface molecule expressed on activated T cells that is suggested to deliver a negative signal for T cell activation. Since CTLA-4 might be a negative regulator of autoimmune diseases, we investigated its expression on T cells from 20 patients with systemic lupus erythematosus (SLE) by flow cytometric analysis and RT-PCR. We found that although CTLA-4 mRNA was readily detected in all patients and controls, only a very minor subset of T cells expressed detectable surface CTLA-4 molecules in both groups. But patients with SLE had significantly increased percentages of CTLA-4-positive T cells compared with normal controls, implying at least that there was no apparent defective expression of CTLA-4 molecule in human lupus. The kinetics of CTLA-4 expression on T cells stimulated in vitro with PMA plus ionomycin were similar in normal controls and patients with SLE. The expression of CTLA-4 molecules after stimulation increased gradually and peaked at 72 hr. However, the induction of CTLA-4 expression on patients' T cells appeared to be weaker than that of normal individuals. Whether this reflects impaired downregulation by CTLA-4 molecules in SLE patients needs to be clarified further.

Abatacept↗

PubMed1998

Selective activation of oncogenic Ha-ras-induced apoptosis in NIH/3T3 cells.

A Ha-ras transformant '7-4', derived from mouse NIH/3T3 fibroblasts, was used to study the relationship between overexpression of activated Ha-ras and cell apoptosis. This cell line contains an inducible Ha-rasVal12 oncogene, which was under the regulation of the Escherichia coli (E. coli) lac operator/repressor system. We demonstrate that overexpression of activated Ha-ras oncogene by exogenous isopropyl-beta-D-thiogalactoside (IPTG) under serum-depleted conditions can stimulate cell apoptosis. Cell cycle analysis showed that most of the 7-4 cells with Ha-ras overexpression accumulated at S-phase and that the expression level of p34cdc2 kinase was decreased, suggesting that p34cdc2 may be involved in 7-4 cell apoptosis. Overexpression of bcl-2 transgene in these cells blocked Ha-ras-induced apoptosis, and this blockage was confirmed downstream of Ha-ras gene expression. Cycloheximide blocked the apoptosis of 7-4 cells in a dose-dependent manner, indicating that specific protein regulating apoptosis may be synthesized through Ha-ras overexpression. Ha-ras overexpression-triggered apoptosis was also prevented in the 7-4 derivatives that express either dominant-negative rasAsn17 or dominant-negative raf-1C4B to suppress Ha-ras signal transduction at different stages, indicating that overexpression of activated Ha-ras can induce cell apoptosis and that raf-1 pathway activity is required for this process.

3T3 Cells↗

PubMed1998

Molecular cloning, characterization and tissue expression of prophenoloxidase cDNA from the mosquito Armigeres subalbatus inoculated with Dirofilaria immitis microfilariae.

A cDNA encoding mosquito Armigeres subalbatus prophenol oxidase (As-pro-PO) was obtained by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) after Dirofilaria immitis inoculation. The 2205 bp As-pro-PO cDNA contains a 32 bp 5'-noncoding region, a 2055 bp open reading frame (685 amino acids), and a 118 bp 3'-noncoding region. Hydrophobic signal peptide for the endoplasmic reticulum targeting is not found in the NH2-terminal region. Two potential copper-binding domains, amino acids 197-245 and 345-412, are highly homologous to those of the other insect pro-POs. A 2.2 kb As-pro-PO transcript was identified by Northern blot analysis using D. immitis microfilariae-inoculated A. subalbatus. Both in situ hybridization and Northern blot analysis demonstrated that As-pro-PO mRNA was synthesized in mosquito haemocytes but not in other tissues, i.e. fat bodies, midguts and ovaries, etc.

Amino Acid Sequence↗

PubMed1998

Lac/Tet dual-inducible system functions in mammalian cell lines.

The Escherichia coli Lac repressor (Lac system) and tetracycline responsive promoter (Tet system) systems have been used individually to regulate gene expression at the cellular as well as the organismal levels. In this study, these two systems were combined (designated Lac/Tet dual-inducible system) to regulate two inducible genes simultaneously in a single cell. The isopropyl-beta-D-thiogalactopyranoside (IPTG) and tetracycline (used for the operation of the Lac and the Tet systems) were non-cytotoxic to the cells when added together into the cells at around the optimal concentrations (IPTG: < or = 5 mM; tetracycline: < 1.5 micrograms). The rate and efficiency of induction and repression of two inducible genes regulated by the Lac/Tet dual-inducible system were similar to the results obtained when one inducible gene is regulated by one inducible system in a single cell. The Lac/Tet dual-inducible system could function in many cell lines, which was demonstrated by regulating the expression of beta-galactosidase and luciferase reporter genes in five tumor cell lines by transient transfection analysis. The feasibility of introducing a second inducible system into an already established inducible cell line was confirmed. Finally, we showed that the Lac/Tet dual-inducible system functions at translational and at functional levels in a stable cell line named 7-4-b, which contains the Ha-ras and bc1-2 inducible genes. In conclusion, this study extends the application of prokaryotic inducible systems from the regulation of a single gene to two genes and helps clarify the relationship between two genes and the effects of two genes on the cells.

Animals↗

PubMed1998

Treatment of giant cell tumor of bone: a comparison of local curettage and wide resection.

BACKGROUND: Giant cell tumor of bone is benign but locally aggressive neoplasm with a tendency for local recurrence. Although various treatment options have been utilized and reported, it remains a difficult therapeutic problem for the orthopedic surgeon. METHODS: We reviewed the results of the treatment of giant cell tumor of bone in 27 patients. Eleven patients were treated with extended curettage and burring then packing with cement, while 16 patients had wide resection and reconstruction. RESULTS: At an average of 50 months after surgery, the recurrence rate of curettage was 27% and that of wide resection was 6.25%. Two of the three patients who had a recurrence after curettage were treated by a secondary curettage procedure and were later free of disease. Overall, the local control rate after second curettage and packing with cement was 90.9%. There was no infection in the curettage group but infection occurred in 3 patients of the resection group. Eight patients in the curettage group (80%) had an excellent functional result but only 2 patients in the resection group (13%) achieved an excellent result. CONCLUSION: This study demonstrates that either curettage and packing with cement or wide resection are effective in treatment of giant cell tumor of bone. There is, however, a better functional result after curettage and packing with cement than following wide resection. We recommend curettage and cement packing for giant cell tumor of bone whenever it is technically feasible.

Adolescent↗

PubMed1998

Comparison of PCA nalbuphine and morphine in Chinese gynecologic patients.

BACKGROUND: The aim of this study was to evaluate the efficacy and side effects of PCA nalbuphine (intravenous) versus morphine on postoperative pain in Chinese gynecologic patients. METHODS: Sixty women undergoing abdominal hysterectomy or myomectomy under spinal anesthesia were enrolled into the investigation. Patients were randomly divided into 2 groups (n = 30 each). Group 1 received intravenous nalbuphine using PCA device for the management of postoperative pain, whereas group 2 received PCA morphine for the same purpose. During the first 48 hours postoperatively, we collected the following data: analgesic doses, pain scores, vital signs, nausea, vomiting, pruritus and dizziness. RESULTS: The results showed that despite different treatments, pain scores on day 1 and day 2 postoperatively were low and were not significantly different between groups. Meanwhile, the cumulative consumption of PCA nalbuphine (32 +/- 10 mg) and PCA morphine (30 +/- 9 mg) was similar. Both treatments showed only minor side effects and the incidence of each side effect was not significant between groups. CONCLUSIONS: Both PCA nalbuphine and morphine are effective in the treatment of postoperative pain in Chinese gynecologic patients undergoing hysterectomy or myomectomy after spinal anesthesia and the potency of nalbuphine is similar to that of morphine.

Analgesia, Patient-Controlled↗

PubMed1997

A ribozyme specifically suppresses transformation and tumorigenicity of Ha-ras-oncogene-transformed NIH/3T3 cell lines.

In this study, the efficacy of an anti-ras ribozyme in reversing a transformed phenotype was investigated. A murine NIH/3T3-derived cell line, designated 2-12, contains an inducible Ha-ras oncogene, which is regulated by the Escherichia coli (E. coli) lac operator/repressor system, and displays a transformed phenotype after isopropyl-beta-D-thiogalactoside induction. To reverse the transformed characteristics, the ribozyme, which specifically targets the Ha-ras oncogene at the codon 12 mutation site (GGC to GUC), was transfected into 2-12 cells. Two (ribZ4 and ribZ7) clones were subsequently selected and analyzed for their transforming features. Our results show that, in the transfectants, ribozyme gene expression was detected, and the target Ha-ras transgene was expressed at basal levels. Their phenotypic responses, including morphology, cell growth rate, colony-formation efficiency and tumorigenicity in mice with severe combined immunodeficiency were more similar to those of NIH/3T3 than 2-12 transformed cells. Directly injecting the ribozyme DNA into tumors induced by transformed 2-12 cells in BALB/c mice also caused tumor regression. The enzymatic cleavage products of the ribozyme acting on mutant Ha-ras mRNA in vivo were detected by primer-extension analysis. These results indicate that the ribozyme were designed exhibits a site-specific ribonuclease function that effectively abrogates Ha-ras-oncogene-induced transformation, and this unique anti-Ha-ras property should shed light on the development of strategies against the Ha-ras-oncogene-initiated malignancy.

3T3 Cells↗

PubMed1997

Expression patterns of erbB receptor family in normal urothelium and transitional cell carcinoma. An immunohistochemical study.

The class I tyrosine kinase growth-factor receptors include epidermal growth factor receptor (EGFR), ErbB2 (c-erbB-2, HER-2/neu), ErbB3 and ErbB4. To elucidate their role in the regulation of homeostasis and carcinogenesis, we examined the expression of the receptors in normal urothelium and in urothelial carcinoma by immunohistochemistry. EGFR was expressed in the basal cells of normal urothelium, while ErbB2, ErbB3 and ErbB4 were present mainly in the superficial layer. A distinct reciprocal distribution was observed between the EGFR and the remaining members of the subclass (P = 0.0001). Both BCL-2 protein and Ki-67 antigen (MIB-1) showed a strong positive association with EGFR (P = 0.002) and an inverse correlation with ErbB2, ErbB3 or ErbB4 (P = 0.0004, 0.0000, and 0.001, respectively). With regard to carcinoma, there was no important relationship between receptor overexpression and tumour grading (P > 0.1), while only EGFR overexpression was correlated with muscular invasion (P = 0.02). Coexpression of EGFR-ErbB3 and ErbB3-ErbB4 was more often detected in high-grade tumours and correlated with the extent of tumour invasion. Our data indicate that class I receptors are differentially expressed in normal urothelium in vivo, but an orchestrated expression pattern does not exist during tumorigenesis.

Carcinoma, Transitional Cell↗

PubMed1997

Antibodies against dengue virus E protein peptide bind to human plasminogen and inhibit plasmin activity.

Both mice and rabbits immunized with dengue virus E protein peptide spanning amino acids 100-119 (D4E) produced antibodies that reacted not only with the D4E peptide itself but also with human plasminogen, as shown by ELISA and Western blot. Sera from dengue virus-hyperimmunized mice and dengue patients also contained antibodies against D4E and plasminogen. Furthermore, such sera all contained plasmin inhibitory activity. Using affinity-purified anti-D4E antibodies and free D4E peptide for competitive inhibition, we demonstrated that the inhibition of plasmin activity was due to anti-D4E antibodies rather than other substances in the sera. Taken together, these results suggest dengue virus E protein amino acids 100-119 are a cross-reactive immunogenic region, and antibodies against this region may interfere with human fibrinolysis.

Animals↗

PubMed1997

The inducible lactose operator-repressor system is functional in the whole animal.

Mouse liver cell lines that bear a stably integrated lactose operon repressor (lacI) gene and a Ha-ras gene linked to a lactose operator-containing SV40 early promoter were generated. When grown in medium containing more than 0.1 mM isopropyl beta-D-thiogalactoside (IPTG), the Ha-ras gene was induced up to 20-fold. Maximum induction of Ha-ras gene expression occurred after 12 h of exposure. The tumorigenicity of these cell lines in syngeneic mice was enhanced when the mice were maintained on drinking water containing 12.5 mM IPTG. Ha-ras gene expression in tumors was strongly induced in the presence of IPTG in vivo. Induction of Ha-ras gene expression in mice was consistently observed after 48 hr of exposure to drinking water containing IPTG. This system provides an approach for studying the function of oncogene in vivo as well as other genes of interest.

Animals↗

PubMed1997

A glycine-to-arginine substitution in the triple-helical domain of type VII collagen in a family with dominant dystrophic epidermolysis bullosa pruriginosa.

Epidermolysis bullosa pruriginosa is a recently recognized variant of dystrophic epidermolysis bullosa (DEB) characterized by severe pruritus and scarring, mainly involving the extensors of the extremities. In this study, we searched for mutations in the type VII collagen gene (COL7A1) using polymerase chain reaction amplification of exonic segments of COL7A1, followed by heteroduplex analysis, in a Chinese pedigree with dominant DEB displaying a striking anastomosing network of lichenoid papules and scarring. The study revealed a G-to-A transition at nucleotide 6724 within exon 85 of COL7A1, converting a glycine to an arginine (G2242R) within the triple-helical domain of the type VII collagen in affected individuals. These findings demonstrate that EB pruriginosa in this family is a clinical variant of dominant DEB.

Adult↗

PubMed1997

Inducible expression of bcl-2 by the lac operator/repressor system in MDCK cells.

The lac operator/repressor-inducible system was utilized to dissect the biological consequences of human bcl-2 gene expression in Madin-Darby canine kidney (MDCK) cells. Cells were made transgenic for a constitutively expressed lacI gene, encoding lac repressor, and the bcl-2 gene that had been inserted downstream of a simian virus 40 (SV40) promoter containing the lac operator sequence. The expression of the bcl-2 gene could therefore be repressed to basal level by binding of lac repressor to the lac operator sequence in proximity to this SV40 regulatory region and be specifically activated by administration of the lactose analog isopropyl-beta-D-thiogalactoside (IPTG). We showed that expression of bcl-2 gene could be induced by 0.01 mM IPTG, and the maximal induction was obtained at 1 mM. With the treatment of IPTG, the Bcl-2 protein could be induced within 6 h. Moreover, the IPTG-inducible expression of Bcl-2 protein is a reversible process. Finally, functional assays revealed that IPTG-induced expression of bcl-2 gene conferred partial or complete resistance to homeless cell death or confluent cell death, respectively. The inducible expression system should be particularly useful for dissecting the effect of bcl-2 in phenotypic or morphological changes of MDCK cells.

Animals↗

PubMed1997

Regulation of infected-cell-specific protein synthesis in SF IPLB-21 cells productively infected with Spodoptera frugiperda multicapsid nuclear polyhedrosis virus.

In Spodoptera frugiperda (SF IPLB-21) cells productively infected with S. frugiperda multicapsid nuclear polyhedrosis virus (SfMNPV), we observed the synthesis of infected-cell-specific polypeptides (ICSPs) using the protein synthesis inhibitor cycloheximide (CX) and the DAN synthesis inhibitor cytosine arabinoside (Ara-C) in an attempt to assess whether a temporal cascade and viral DNA synthesis are involved in the gene expression program of SfMNPV. Inhibition of protein synthesis with CX at 0 h postinfection resulted in the active synthesis of a group of ICSPs immediately after removal of CX, suggesting that these polypeptides, designated alpha-ICSP, did not require de novo protein synthesis for their production. A second group of ICSPs (designated beta-ICSPs), requiring a prior interval of protein synthesis, was detected when CX was added at later times. A third group of ICSPs also needed an interval of ICSP synthesis, but differed from beta-ICSPs in that they required a longer interval of protein synthesis. Moreover, the synthesis of most of these ICSPs also required DNA synthesis, which was demonstrated by addition of Ara-C before and after viral DNA replication; these ICSPs were therefore designated gamma-ICSPs. In conclusion, two kinds of regulatory processes are involved in SfMNPV infection: the first process controls the sequential synthesis of the tree ICSP groups, that is alpha-->beta-->gamma; a second process represses the synthesis of ICSP groups, first of the alpha-ICSPs and subsequently of beta-ICSPs. Thus, we propose temporally regulated as well as negative control circuits in SfMNPV gene expression.

Animals↗

PubMed1997

The incidence of post dural puncture headache in Taiwanese patients undergoing cesarean section.

BACKGROUND: In Taiwan, there was only a retrospective study about the post-dural puncture headache (PDPH) resulting from spinal anesthesia for cesarean section (C/S), but it did not mention the relationship between the incidence of PDPH and the number of dural punctures, as well as between the gauge of spinal needle. Therefore, we designed a prospective study to investigate if the spinal needles for smaller gauges could decrease the incidence of PDPH in anesthesia for C/S. METHODS: From Jan. 1990 to June 1991 we prospectively observed 2,385 consecutive cases of spinal anesthesia for various types of surgical procedures, of which 584 were C/S. The spinal needles used were of gauges 24, 25 and 26. In practice, needles of these gauges were randomly applied. The PDPH was observed until its disappearance, and nonexistence of PDPH was also followed for at least one week. All of the data were analyzed using the Fisher exact test. RESULTS: The overall incidence of PDPH was 1.18%. The incidence of PDPH in C/S females was 3.08%, which was significantly higher than that in non-obstetric females (0.37%). Although the incidence in all females (1.31%) was significantly higher than that in males (0.71%), the incidence in non-obstetric females (0.37%) did not differ significantly compared with males. The incidence of PDPH relevant to the gauges of spinal needle used was not statistically different in C/S females. CONCLUSIONS: It appears that the incidence of PDPH does not differ between Taiwanese and Westerners. Pregnancy may be the key factor contributing to higher incidence of PDPH. The 26-gauge spinal needle may lower the incidence of PDPH to a greatest extent in C/S patients, although in comparison with 24- and 25-gauge needles the difference is not statistically significant.

Adolescent↗

PubMed1997

Post dural puncture headache in cesarean section: comparison of 25-gauge Whitacre with 25- and 26-gauge Quincke needles.

BACKGROUND: Our previous study showed that there were no significant differences in the incidence of post dural puncture headache (PDPH) relevant to the use of 24 to 26-gauge Quincke spinal needles in obstetric patients. Again, we were eager to know if the pencil-point spinal needle (Whitacre) would be able to decrease the incidence of PDPH compared to Quincke spinal needle. METHODS: We prospectively observed 94 spinal anesthesias for cesarean section performed during the period from May 1993 to July 1995. The 25-gauge Whitacre needles were used. In practice the insertion of needle was made through median line approach and the puncture was considered eligible only in one attempt. The PDPH was observed until its disappearance, and one without PDPH had also been observed for at least one week for likelihood of delayed occurrence. The data were compared with those of our previous study regarding the use of 25- and 26-gauge Quincke needles in obstetric patients. All of the data were analyzed using the Fisher exact test. RESULTS: The incidence of PDPH was 1.06%. In comparison there was no significant difference from that of 25- and 26-gauge Quincke needles (3.65% and 2.06%, respective). Only one case suffered from PDPH in the Whitacre group. It was mild and relieved with bed rest and hydration. CONCLUSIONS: Although the difference was not statistically significant, the 25-gauge Whitacre spinal needle caused a lower incidence and less severity of PDPH than the 25- and 26-gauge Quincke needles did.

Adult↗

PubMed1997

The preemptive effect of pre-incisional bupivacaine infiltration on postoperative analgesia following lower abdominal surgery under epidural anesthesia.

BACKGROUND: In attempts to reduce central sensitization after tissue injury, the concept of preemptive analgesia has evolved. The aim of the present study was to evaluate the preemptive effect of pre-incisional infiltration of the surgical area with bupivacaine on pain following lower abdominal surgery under epidural anesthesia. METHODS: Sixty female patients scheduled for lower abdominal surgery under epidural anesthesia with bupivacaine were randomly divided into two Groups (n = 30, each). Five minutes before surgical incision, patients in Group 1 received subcutaneous infiltration of the proposed surgical area with 30 ml of 0.125% bupivacaine (with 1/200,000 epinephrine), while those in Group 2 received 30 ml of isotonic saline (with 1/200,000 epinephrine) infiltration. Postoperatively, pain was assessed for 48 h by a visual analogue scale of pain at rest, during cough and by cumulative morphine doses (self-administered by patient-controlled analgesia). RESULTS: The pain score at rest was significantly lower in Group 1 than in Group 2 from the 6th h to the 24th h postoperatively. The cough-associated pain score was lower in Group 1 than in Group 2 from the 6th h to the 28th h postoperatively. Furthermore, Group 1 consumed less morphine than did Group 2 from the 6th h to the 24th h postoperatively. CONCLUSIONS: The results indicate that pre-incisional infiltration of surgical area with bupivacaine markedly decreases the intensity of pain following lower abdominal surgery under epidural anesthesia.

Abdomen↗

PubMed1997

The analgesic effect of PCA buprenorphine in Taiwan's gynecologic patients.

BACKGROUND: The aim of this study was to evaluate the analgesic effect of PCA buprenorphine (intravenous) on postoperative pain in gynecologic patients of Taiwan and the potency ratio of buprenorphine versus morphine, a commonly used potent analgesic. METHODS: Fifty women undergoing abdominal total hysterectomy under spinal anesthesia were enrolled into the investigation. Patients were randomly divided into 2 groups (n = 25 each). Group 1 received intravenous buprenorphine using PCA device for the management of postoperative pain, whereas Group 2 received PCA morphine for the same purpose. During the first 48 hours postoperatively, we collected the following data: demand and delivery of analgesics, pain scores, vital signs, nausea, vomiting and pruritus. RESULTS: Despite different treatments, we found that pain scores on day 1 and day 2 postoperatively were low and were not significantly different between groups. Also, times of demand for delivery of PCA medication were not significantly different between groups. The cumulative consumption of buprenorphine and morphine within 48 h were 1.5 +/- 0.6 mg and 36 +/- 7 mg, respectively. The potency ratio between buprenorphine and morphine was 24:1. Both treatments showed only minor side effects. CONCLUSIONS: We found that PCA buprenorphine (intravenous) could be effective in the treatment of postoperative pain in the gynecologic patients in Taiwan and the potency ratio of buprenorphine versus morphine appeared to be 24:1.

Analgesia, Patient-Controlled↗

PubMed1997

Comparison of various methods of detection of different forms of dengue virus type 2 RNA in cultured cells.

In this report, the sensitivity of various methods of detection of dengue virus type 2 (DEN-2) sense, antisense, replicative intermediate (RI) and replicative form (RF) RNAs in infected mosquito Aedes pseudoscutellaris AP-61 and mammalian baby hamster kidney BHK-21 cells is compared. LiCl precipitation was used for separation of viral RF RNA from RI RNA. Our results show that reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot analysis and slot blot hybridisation of LiCl-fractionated RNA were the most sensitive methods of detection of viral RNA and determination of its single-stranded form. Northern blot analysis was the least sensitive method of detection of any form of viral RNA. Using slot blot hybridisation of LiCl-precipitated RNA, viral RI RNA containing de novo synthesised negative strand viral RNA was first detected 30 mins after virus inoculation in both cell lines. This is the earliest time of detection of DEN viral RNA synthesis in host cells so far reported. However, RF RNA could not be detected until 24 hrs post infection (p.i) in AP-61 and 2 days p.i. in BHK-21 cells, respectively. The sequential order of individual forms of viral RNA detected in the infected cells was RI, RF and genomic RNAs. Viral RNA was detected in AP-61 cells always earlier than in BHK-21 cells. Moreover, the level of viral RNA in AP-61 cells was higher than that in BHK-21 cells, suggesting that the virus replicated more actively in AP-61 cells. In conclusion, the LiCl separation of viral RNA followed by slot blot hybridisation was found to be the most sensitive and reliable method of detection of DEN virus RI, RF and genomic RNAs in the infected cells. Moreover, this method can be applied to determine the replication status of any single-stranded RNA virus in the host.

Aedes↗