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Biomedical subjects

C Huang

Publications and source records attributed to C Huang.

At least 397 records · Page 22Linked to original sources
PubMed1995

Construction, expression and the characterization of t-PA mutants with increased plasma half-life and resistance to inhibition by PAI-1.

Three t-PA mutants, t-PA del K1 (with deletion of K1 domain), t-PA del (296-302) (with deletion of PAI-1 binding site) and their combination mutant t-PA del (K1, 296-302), were constructed by DNA recombination and site-directed mutagenesis techniques. Then the three t-PA mutants were transiently expressed in COS-7 cells, and in addition, the combination mutant t-PA del (K1, 296-302) was stably expressed in CHO cells. The biological analysis of the expression products demonstrated that t-PA del (296-302) and t-PA del (K1, 296-302) had obtained the resistance to inhibition by PAI-1. In addition, the half-life of t-PA del (K1, 296-302) in rat plasma was increased 6 fold while the mutant affinity for fibrin was only slightly affected. Therefore, it was reasonable to consider that the mutant t-PA del (K1, 296-302) may become a potent candidate of new thrombolytic agent.

Animals↗
PubMed1995

[Female lung cancer].

One hundred and ninety one women were diagnosed with lung cancer at our hospital. This comprised 23.7% of all lung cancer cases. Smoking habits were significantly lower in female lung cancer. Adenocarcinoma is the most common histological type of female lung cancer (64.2%). The prognoses of asymptomatic cases detected by regular examination were significantly better than those of symptomatic cases. Among resectable cases of either adenocarcinoma or squamous cell carcinoma, there were no significant differences between the prognosis for women and that for men. However, the prognosis for nonresectable cases of adenocarcinoma in women was significantly better in the 2-year survival rate (30.8%) than the prognosis for such cases in men. Since the periphery type is the most common site of adenocarcinoma in women, educating women, especially those in the high-risk group, and persuading them to undergo regular examinations are important step to increasing early-stage detection and cure.

Adenocarcinoma↗
PubMed1995

Inhibitory effect of 3'-untranslated region (3'-UTR) of human tissue-plasminogen activator (ht-PA) mRNA on its expression.

A series of t-PA cDNA mutants containing different parts of 3'-UTR sequences have been constructed. In vitro translation of t-PA transcripts in rabbit reticulocyte lysates and its expression in COS-7 cells show that the 3'-UTR sequence has a very strong inhibitory effect on t-PA translation. The deletion of 3'-UTR results in 3-8-fold increase of t-PA expression. Further study shows that an AU-rich sequence of some 200 nt at 3' end of 3'-UTR is responsible for the translational inhibition. RNA stability experiment reveals that the AU-rich segment leads to a 3-fold decrease of t-PA mRNA stability. The insertion of this segment into the 3'-UTR of luciferase gene results in an obvious inhibition of Luc expression. A model is proposed for the regulation of t-PA expression.

Animals↗
PubMed1995

Immune response to synthetic peptides representing antigenic sites on the glycoprotein of infectious hematopoietic necrosis virus.

Monoclonal antibodies against infectious hematopoietic necrosis virus have been used to react with recombinant expression products in immunoblots and to select neutralization-resistant mutants for sequence analysis. These strategies identified neutralizing and non-neutralizing antigenic sites on the viral glycoprotein. Synthetic peptides based upon the amino acid sequences of these antigenic sites were synthesized and were injected together with an adjuvant into rainbow trout. The constructs generally failed to stimulate neutralizing antibodies in the fish. These results indicate that we need to understand more about the ability of peptide antigens to stimulate fish immune systems.

Animals↗
PubMed1995

[Cloning of a cluster of genes encoding coli-surface antigen 6(CS6) of human enterotoxigenic E. coli].

A gene library was constructed from large plasmid DNA of wild strain E519/66A of human enterotoxigenic Escherichia coli (ETEC). Positive colonies containing CS6 antigen were obtained. The CS6 gene fragment was identified by restriction endonuclease mapping. It was approximately 4.6 kb in length and responsible for encoding CS6 genes and regulating the CS6 antigen. Two forms of fimbriae protein with different molecular weight were produced by the selected clones. Both of them could react with the same CS6 antiserum. So we expect to use the recombinant strain as candidate for human ETEC vaccine development, and it is also useful for further research on the expression and regulation of genes encoding CS6 fimbriae protein.

Antigens, Bacterial↗
PubMed1995

[Surgical treatment of obstructive jaundice caused by hepatocellular carcinoma].

Between Jan. 1991 and Dec. 1993, 7 patients with obstructive jaundice caused by hepatocellular carcinoma underwent transcholedochal cancerous embolectomy plus T-tube drainage of the biliary tract, in 5 patients with hepatectomy. Detailed discussion was made an the operative procedure and the operative results. The authors indicated that intensive surgical operation is effective in relieving symptoms and prolonging life-span.

Adult↗
PubMed1995

[An approach to the diagnosis of recurrent attack of rheumatic fever in patients with rheumatic heart disease].

In order to evaluate recurrent attack of rheumatic fever (RARF) in patients with rheumatic heart disease (RHD), 97 patients with diagnosis of RHD for two years and more were included in this study. Progression of the lesions of cardiac valves was found in every case by comparing the echocardiographic and Doppler findings at present and two years ago. The history of the initial attack of acute rheumatic fever or the appearance of RHD were reviewed. The present complaints at admission and necessary laboratory procedures were studied. The data showed that 75 of the 97 patients had history of initial attack of ARF and the remaining 22 were symptomless with indolent carditis or carditis of insidious onset two years ago. In this admission, only 25 of the 97 patients had ARF in the Jones criteria were followed strictly, while the remaining 72 did not fulfill the criteria. It is suggested that if there is evidence of recent group a streptococcal infection, the conditions for diagnosis of RARF are as follows: 1) When one major or more than two minor criteria are present in a patient with RHD, a definite diagnosis of RARF may be made. 2) A presumptive diagnosis of RARF may be made, when a patient presents one minor criteria and several other manifestations such as anemia, abdominal pain, rapid sleeping pulse rate, tachycardia out of proportion to fever, malaise, epistaxis, precordial pain and an elevated level of IgG, IgA, C3 and circulating immune complexes.

Adolescent↗
PubMed1995

[Evaluation of surgical resection for gastric cancer extending to adjacent organs].

From June 1972 to December 1993, 280 patients underwent surgical resection for their gastric cancer extending to adjacent organs. The patients were divided into three groups. Group A, 93 patients, were treated with gastrectomy plus complete removal of the invaded organs. Group B, 55 patients, underwent gastrectomy with incomplete removal of the invaded organs. Group C, 132 patients underwent gastrectomy only. The 5 year survival rate of each group was 32.7%, 7.7% and 4.4%, respectively. The 5 year survival rate in the group A was significantly higher than that in two other 2 groups (P < 0.05). The 5 year survival rate in the group B and C was similar (P > 0.05). The patients without incurable factors (liver metastasis, peritoneal dissemination and widespread nodal involvement) underwent gastrectomy with complete excision of invaded organs, irrespective of the number or site of invaded organs. On the other hand, the patients with incurable factors should be given palliative gastrectomy only. Because symptoms are alleviated, the quality of life is improved and the survival time is prolonged.

Adult↗
PubMed1995

Construction, expression and characterization of tissue-type plasminogen activator mutants.

Three tissue-type plasminogen activator (t-PA) mutants were constructed by recombinant and site-directed mutagenesis techniques. They are del(296-302) with deletion of PAI-1 binding site, N117Q/N184Q with deglycosylation of K1 and K2 domains, and their combination mutant designated as GGI. Then these three mutants were successfully transiently expressed in COS-7 cells, and GGI was further stably expressed in CHO cells. The biological characterization of the expression products indicated that del(296-302) and GGI possessed the resistance to inhibition by PAI-1. In addition, the specific activity of GGI was increased by about 46%, the plasma half-life was prolonged by about one fold, while its affinity for fibrin was not affected.

Animals↗
PubMed1994

On the main phase transition temperatures of highly asymmetric mixed-chain phosphatidylcholines.

The highly asymmetric mixed-chain phosphatidylcholines or C(X):C(Y)PC, which can self-assemble at T < Tm into the mixed interdigitated gel-state bilayer in excess water, can be divided into two groups. Group I consists of C(X):C(Y)PC with X > Y, and Group II consists of C(X):C(Y)PC with X < Y. The main phase transition temperatures (Tm) of these C(X):C(Y)PC have been analyzed in terms of two structural parameters (delta and Nf). Specifically, these structural parameters are related to the packing geometry of the lipid's acyl chains as the lipid molecules are packed either in a mixed (delta) or a hypothetically partially (Nf) interdigitated packing motif at T < Tm. Based on 28 and 29 Tm values of Group I and II C(X):C(Y)PC, two general equations are derived, respectively, by multiple regression analyses. These equations correlate systematically the Tm values of Group I and II phosphatidylcholines with their corresponding structural parameters. Using these two derived equations, the Tm values of a total of 92 molecular species of C(X):C(Y)PC are generated, and these calculated Tm values can be considered as the reliably predicted Tm values for highly asymmetric C(X):C(Y)PC which have delta C/CL values within the range of 0.42-0.66.

Calorimetry, Differential Scanning↗
PubMed1994

Alcohol induces interdigitated domains in unilamellar phosphatidylcholine bilayers.

Using the atomic force microscope (AFM) in situ, we have demonstrated that acyl chain interdigitation can be induced reversibly by alcohol in supported unilamellar phospholipid bilayers. At alcohol concentrations considerably lower than the critical values determined by other experimental techniques, it was found that interdigitated domains can be induced and these domains were stable over a long period of time. The mechanism of such domain formation remains to be elucidated. This work also serves as an example to illustrate the uniqueness of the AFM as a powerful tool in the study of membrane structure and conformation under physiological conditions at high spatial resolution.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

The Chlamydomonas chloroplast clpP gene contains translated large insertion sequences and is essential for cell growth.

Sequence determination of the chloroplast clpP gene from two distantly related Chlamydomonas species (C. reinhardtii and C. eugametos) revealed the presence of translated large insertion sequences (IS1 and IS2) that divide the clpP gene into two or three sequence domains (SDs) and are not found in homologous genes in other organisms. These insertion sequences do not resemble RNA introns, and are not spliced out at the mRNA level. Instead, each insertion sequence forms a continuous open reading frame with its upstream and downstream sequence domains. IS1 specifies a potential polypeptide sequence of 286 and 318 amino acid residues in C. reinhardtii and C. eugametos, respectively. IS2 encodes a 456 amino acid polypeptide and is present only in C. eugametos. The two Chlamydomonas IS1 sequences show substantial similarity; however, there is no significant sequence similarity either between IS1 and IS2 or between these insertion sequences and any other known protein coding sequences. The C. reinhardtii clpP gene was further shown to be essential for cell growth, as demonstrated through targeted gene disruption by particle gun-mediated chloroplast transformation. Only heteroplasmic transformants could be obtained, even under mixotrophic growth conditions. The heteroplasmic transformants were stable only under selection pressure for the disrupted clpP, rapidly segregated into wild-type cells when the selection pressure was removed, and grew significantly more slowly than wild-type cells under phototrophic conditions.

ATP-Dependent Proteases↗
PubMed1994

Regulation of the Yp subunit of glutathione S-transferase P in rat embryos and yolk sacs during organogenesis.

Manipulation of the glutathione status of an embryo during organogenesis leads to abnormal development, as well as increasing the susceptibility of the embryo to insult by either xenobiotic or endogenous electrophiles. The glutathione S-transferases are a family of drug-metabolizing enzymes that catalyze the conjugation of reactive chemicals with glutathione, playing an important role in protecting cells against attack. The purpose of this study was to investigate the presence and regulation of one glutathione S-transferase, glutathione S-transferase P, a homodimer of the Yp subunit, in the conceptus during organogenesis. Northern blot analysis of the RNA isolated from rat embryos and their yolk sacs on days 10, 11 and 12 of gestation revealed a single Yp transcript. Steady-state concentrations of the Yp mRNA in embryos did not change with either gestational age or culture for 24 hr (day 11 in vitro) or 45 hr (day 12 in vitro). In contrast, concentrations of this transcript in yolk sac increased 3-fold from day 10 to 12 of gestation and a further 3-fold with culture (day 12 in vivo compared with in vitro). Transcription of the rat Yp subunit gene in cell lines is induced by treatment with phorbol esters. However, the addition of 12-O-tetradecanoylphorbol-13-acetate (TPA, 50 or 100 nM) to embryos in culture had no effect on the steady-state concentrations of the Yp transcript. Thus, the glutathione S-transferase Yp message is subject to tissue- and development-specific regulation in the conceptus during organogenesis. Moreover, culture of the embryos resulted in a further up-regulation of the steady-state concentrations of the Yp transcript in yolk sac. Western blot analysis demonstrated that a single immunoreactive Yp subunit band of 26 kDa was found in both embryos and yolk sacs. Neither age nor culture appeared to affect the concentrations of immunoreactive Yp subunit in the yolk sac. Thus, glutathione S-transferase Yp mRNA is translated in the conceptus during organogenesis. The apparent differences between the relative amounts of the message and immunoreactive protein in yolk sac suggest that this subunit may be subject to post-transcriptional as well as transcriptional regulation in this tissue. Immunohistochemical analysis of embryos cultured for 45 hr (day 12 in vitro) revealed that the Yp reaction product was localized over the hepatic primordia, mesonephric ducts, otocyst, yolk sac and ectoplacental cone.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Interconversion of bilayer phase transition temperatures between phosphatidylethanolamines and phosphatidylcholines.

High-resolution differential scanning calorimetric studies were performed to investigate the thermotropic phase behavior of 31 molecular species of phosphatidylethanolamines in excess water. Upon reheating, the aqueous dispersions of these lipids undergo the gel to liquid-crystalline phase transitions at well defined temperatures (Tm). These Tm values were shown to relate to the structural parameters of the underlying lipid molecules in a characteristic manner. Based on these observations, an interconversion of the Tm values between saturated phosphatidylethanolamines and phosphatidylcholines is established quantitatively for the first time.

Calorimetry, Differential Scanning↗
PubMed1994

Increase in cytoskeletal actin induced by inositol 1,4-bisphosphate in saponin-permeated pig platelets.

Inositol 1,4-bisphosphate (IP2) which rapidly accumulates during cell activation, strongly stimulates an increase in cytoskeletal actin in saponin-permeated platelets, and the effect is insensitive to 5'-Chloro-5'-deoxyadenosine. Within 10 s, the amount of cytoskeletal actin in platelets rapidly increases by 41%, and then slowly increases further. IP2 induces the increase in cytoskeletal actin in a dose-dependent manner. The half-maximal effect requires approximately 2 microM of IP2. Inositol 1,4,5- triphosphate, the messenger for Ca2+ release, causes the increase in cytoskeletal actin, but is less effective than IP2. Inositol 1-monophosphate and inositol 2-monophosphate have no effect on cytoskeletal actin. Phorbol 12-myristate 13-acetate, which has been shown to activate IP3 5'-phosphatase through protein kinase C, stimulates the increase in cytoskeletal actin. Spermine, an inhibitor of IP3 5'-phosphatase, inhibits the thrombin stimulated increase in cytoskeletal actin. These results suggest that IP2 may be a messenger that controls the organization of actin filaments during cell activation. This study presents the first evidence for IP2 as a messenger during cell activation.

Actins↗
PubMed1994

Anthropometry of Taiwanese women.

This note describes the results of research into the anthropometric measurements of women in Taiwan, for use in pantihose design.

Journal Article↗
PubMed1994

Identification and characterization of kink motifs in 1-palmitoyl-2-oleoyl- phosphatidylcholines: a molecular mechanics study.

As a cis carbon-carbon double bond (delta) is introduced into the middle of an isolated all-trans hydrocarbon chain, it can be shown by molecular graphics that this delta-bond makes a bend of 130 degrees in the chain axis, thus producing a boomerang-like conformation. Such a bent structure, indeed, has been detected experimentally for oleic acid by x-ray crystallography (Abrahamson and Ryderstedt-Nahringbaur, 1962). Membrane diacyl phospholipids are largely mixed-chain lipids containing a saturated sn-1 acyl chain and an unsaturated sn-2 acyl chain. 1-Palmitoyl-2-oleoyl-phosphatidylcholine (POPC), the most abundant phospholipid in animal cell membranes, is a typical example in which the sn-2 acyl chain is the acyl chain of an oleic acid. However, this sn-2 acyl chain of POPC is unlikely to adopt a boomerang-like configuration in the gel-state lipid bilayer due to the steric hindrance imposed by neighboring chains. Instead, it has been suggested that the oleate chain in POPC is kinked in the shape of a crankshaft in the gel-state bilayer (Huang, 1977; Lagaly et al., 1977), because POPC with such a kinked sn-2 acyl chain, which is denoted here as the secondary structural element or motif, can pack efficiently against other neighboring phospholipids. In this communication, 16 different types of secondary structural elements or motifs are derived for POPC at T < Tm based on a single protocol guided by two-dimensional steric contour maps and computer-based molecular graphics. After subjecting these derived molecular species to energy minimization using the molecular mechanics method, the number of the secondary structural motifs is reduced to 13 as a result of conformational degeneracy. The structure and steric energy of each of the energy-minimized lipid rotomers are presented in this communication. Furthermore, these rotomers packed in small clusters are also simulated to mimic the lipid bilayer structure of 1-palmitoyl-2-oleoyl-phosphatidylcholines at T < Tm.

Calorimetry↗