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Biomedical subjects

T Y Liu

Publications and source records attributed to T Y Liu.

At least 91 records · Page 5Linked to original sources
PubMed1991

Limunectin. A phosphocholine-binding protein from Limulus amebocytes with adhesion-promoting properties.

A protein that binds to and precipitates with pneumococcal C-polysaccharide and a phosphocholine (PC) derivative of bovine serum albumin has been affinity purified from Limulus amebocytes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis reveals that the isolated protein consists of a single polypeptide chain of approximately 50 kDa. It is an intracellular protein localized in the secretory granules of amebocytes according to immunogold staining. Although it shares the PC-binding property with C-reactive protein isolated from Limulus and other animal species, it differs from C-reactive protein in that the latter binds to PC only in the presence of Ca2+, whereas the newly isolated protein binds to PC in a Ca(2+)-independent manner. In this respect, the newly isolated PC-binding protein resembles the antibodies to PC of mouse myelomas. The gene coding for this protein has been isolated. The gene sequence predicts a protein of 54 kDa with an unusual structural feature: it consists almost entirely of 10 contiguous segments, 45 amino acids in length, with extensive homology. Some limited sequence homologies were found between the 54-kDa protein and segments of vitronectin, gelatinase, and collagenase. It binds to bacterial cells, fixed amebocytes, and a number of extracellular matrix molecules. Due to its structural and some functional similarities to other adhesion molecules, the Limulus 54-kDa protein was named "Limunectin."

Amino Acid Sequence↗
PubMed1991

Systemic amyloidosis presenting as splenic tumor.

We report a case of amyloidosis manifesting as a splenic tumor and pleural effusion. Only one case of a splenic amyloid tumor has been reported in the literature, but its radiological findings were not described. Therefore, we present the computed tomographic (CT), sonographic, and angiographic features of splenic amyloid tumor.

Amyloidosis↗
PubMed1991

Effect of aging on phosphate metabolites of rat brain as revealed by the in vivo and in vitro 31P NMR measurements.

Changes of phosphate metabolism in brains of neonate, weaning and adult rats were compared using both in vivo and in vitro nuclear magnetic resonance spectra. Ratios of phosphocreatine/nucleoside triphosphate (PCr/NTP) were the same in neonatal brain in both in vivo and in vitro studies, but not in weaning and adult brains. This discrepancy may have resulted from extended cerebral hypoxia due to slowed freezing of the brain by the increased skull thickness and brain mass in the weaning and adult rats. Variations in in vitro extraction condition for this age-related study may lead to systematic errors in the adult rats. Nevertheless, the phosphomonoester/nucleoside triphosphate (PME/NTP) ratios in extracts of brain from neonatal rats were higher than those obtained in vivo. In addition, the glycerophosphorylethanolamine plus glycerophosphorylcholine/nucleoside triphosphate (GPE+GPC/NTP) ratios, which were not measurable in vivo, showed age-dependent increase in extracts of rat brain. Some of the phosphomonoester and phosphodiester molecules in rat brain may be undetectable in in vivo NMR analysis because of their interaction with cellular components. The total in vitro GPE and GPC concentration in brain from neonatal rat was estimated to be 0.34 mmole/g wet tissue.

Aging↗
PubMed1991

Hormonal therapy for hepatocellular carcinoma.

Hepatocellular carcinoma is not only the leading cause of male cancer death in Taiwan, but also one of the most common cancers in the world. The survival of hepatocellular carcinoma patients is very low, mainly due to the lack of effective treatments. Radiation and chemotherapies in general are not satisfactory: surgery itself is the most effective treatment for hepatocellular carcinoma but only on small resectable tumors. The overall prognosis is still poor. Previously, we have found that the level of glucocorticoid receptor and its mRNA in hepatocellular carcinoma was significantly higher than that of the adjacent liver tissue. This correlated well with the elevated serum alpha-fetoprotein levels in patients with hepatocellular carcinoma. Recently, a female hormone, progesterone, has been found to inhibit the expression of alpha-fetoprotein in hepatoma cells. In addition, progesterone has been used to treat a few hepatocellular carcinoma patients with promising responses. These results together with our hypothesis that the expression of alpha-fetoprotein is regulated by glucocorticoid receptor complex in proliferating hepatocellular carcinoma cells lead to the conclusion that steroid hormones and/or their antagonists may interfere with the function of glucocorticoid receptors in tumors, consequently regulate tumor growth. The potential of hormonal therapy for treatment of hepatocellular carcinoma is worthy of further investigation.

Carcinoma, Hepatocellular↗
PubMed1991

Baclofen-induced frontal lobe syndrome: case report.

An 81-year-old man with cervical spondylotic myelopathy developed an acute frontal lobe like syndrome with prominent preservation and an abnormal electroencephalogram after being given seven doses (70 mg) of baclofen for spasticity. The clinical symptoms cleared up in 72 hours after the medication was discontinued.

Aged↗
PubMed1991

HTLV-1-associated myelopathy: first case reported in Taiwan.

Taiwan is geographically, culturally, and socially close to southern Japan, which is an endemic area of human T-lymphotropic virus type 1-associated myelopathy (HAM). Taiwan, however, is not an endemic area of HAM. We report the first case of HAM in a native Taiwanese, a 61-year-old woman, without known HTLV-1 risk factors.

Female↗
PubMed1991

Analysis of monoamines in the cerebrospinal fluid of Chinese patients with Alzheimer's disease.

We have established HPLC assay conditions that could measure the levels of 14 monoamines and their metabolites simultaneously. Monoamine levels in cerebrospinal fluids of 12 Chinese patients with Alzheimer's disease were compared with those in samples from patients with benign prostate hyperplasia. Of the 14 monoamines and metabolites, only three were found to be present in all samples. Although the levels of 5-hydroxy-3-indoleacetic acid (HIAA) and homovanillic acid (HVA) in cerebrospinal fluid of patients with Alzheimer's disease were lower, and the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) higher, as compared to control patients, no significant differences were found between these two groups.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Specific binding of host cell proteins to the 3'-terminal stem-loop structure of rubella virus negative-strand RNA.

At the 5' end of the rubella virus genomic RNA, there are sequences that can form a potentially stable stem-loop (SL) structure. The complementary negative-strand equivalent of the 5'-end SL structure of positive-strand rubella virus RNA [5' (+) SL structure] is thought to serve as a promoter for the initiation of positive-strand synthesis. We screened the negative-strand equivalent of the 5' (+) SL structure (64 nucleotides) and the adjacent region of the negative-strand RNA for their ability to bind to host cell proteins. Specific binding to the 64-nucleotide-long potential SL structure of three cytosolic proteins with relative molecular masses of 97, 79, and 56 kDa was observed by UV-induced covalent cross-linking. There was a significant increase in the binding of the 97-kDa protein from cells upon infection with rubella virus. Altering the SL structure by deleting sequences in either one of the two potential loops abolished the binding interaction. The 56-kDa protein also appeared to bind specifically to an SL derived from the 3' end of positive-strand RNA. The 3'-terminal structure of rubella virus negative-strand RNA shared the same protein-binding activity with similar structures in alphaviruses, such as Sindbis virus and eastern equine encephalitis virus. A possible role for the host proteins in the replication of rubella virus and alphaviruses is discussed.

Animals↗
PubMed1991

[Post-operative evaluation of 1000 consecutive hemorrhoid cases].

From September 1983 to October 1988, one thousand consecutive hemorrhoid patients were hospitalized and treated at T.C.V.G.H.A retrospective evaluation based on their admission charts was conducted. Two surgical procedures, wedge hemorrhoidectomy and anoplasty, were compared. We collected and analyzed the following data: sex, age, surgical procedure, post-operative pain, complications and number of days of hospitalization. This study discovered that the larger the major operative area and the greater the number of suture knots, the severer the post-operative pain. For instance, anoplasties resulted in a higher incidence of urine retention (78.1%) and stool impaction (79.4%) than hemorrhoidectomies did. Early complications were found primarily in cases receiving anoplasty, but in later complications, there were no significant differences found between procedures. Anoplasty also resulted in a longer hospital stay, so when dealing with the same degree of hemorrhoid, the simpler the operation, the better the result, because the patients' discomfort can be reduced and hospitalization can be shortened.

Adult↗
PubMed1990

Spermidine biosynthesis in Saccharomyces cerevisiae. Biosynthesis and processing of a proenzyme form of S-adenosylmethionine decarboxylase.

We have cloned and sequenced the Saccharomyces cerevisiae gene for S-adenosylmethionine decarboxylase. This enzyme contains covalently bound pyruvate which is essential for enzymatic activity. We have shown that this enzyme is synthesized as a Mr 46,000 proenzyme which is then cleaved post-translationally to form two polypeptide chains: a beta subunit (Mr 10,000) from the amino-terminal portion and an alpha subunit (Mr 36,000) from the carboxyl-terminal portion. The protein was overexpressed in Escherichia coli and purified to homogeneity. The purified enzyme contains both the alpha and beta subunits. About half of the alpha subunits have pyruvate blocking the amino-terminal end; the remaining alpha subunits have alanine in this position. From a comparison of the amino acid sequence deduced from the nucleotide sequence with the amino acid sequence of the amino-terminal portion of each subunit (determined by Edman degradation), we have identified the cleavage site of the proenzyme as the peptide bond between glutamic acid 87 and serine 88. The pyruvate moiety, which is essential for activity, is generated from serine 88 during the cleavage. The amino acid sequence of the yeast enzyme has essentially no homology with S-adenosylmethionine decarboxylase of E. coli (Tabor, C. W., and Tabor, H. (1987) J. Biol. Chem. 262, 16037-16040) and only a moderate degree of homology with the human and rat enzymes (Pajunen, A., Crozat, A., Jänne, O. A., Ihalainen, R., Laitinen, P. H., Stanley, B., Madhubala, R., and Pegg, A. E. (1988) J. Biol. Chem. 263, 17040-17049); all of these enzymes are pyruvoyl-containing proteins. Despite this limited overall homology the cleavage site of the yeast proenzyme is identical to the cleavage sites in the human and rat proenzymes, and seven of the eight amino acids adjacent to the cleavage site are identical in the three eukaryote enzymes.

Adenosylmethionine Decarboxylase↗
PubMed1990

cis-acting elements responsible for interleukin-6 inducible C-reactive protein gene expression.

To study the mechanism of induction of human C-reactive protein (CRP) gene expression, we have utilized an in vitro liver cell system to analyze the cis-acting DNA sequences located within the 5'-flanking region of human CRP gene. Stable transfection of human hepatoma cells, PLC/PRF/5, by a CRP gene construct containing the 1 kilobase pair of upstream sequence of the CRP gene demonstrated that this region contained the inducible element(s) which regulated human CRP gene transcription. Dissection of this region by 5', 3' and internal deletion constructs of upstream region of the CRP gene fused to a reporter gene, chloramphenicol acetyl transferase, indicated the presence of two inducible elements located proximal to the site of initiation of transcription, two constitutive enhancer-like elements located distal to the promoter, and a negative regulatory region located between the two inducible elements. We had previously shown that a protein factor from monocytes or HTLV1-infected T-cells, was responsible for CRP induction in hepatoma cells. We have found this factor to be synonymous with interleukin-6. By stable and transient transfection assays in hepatoma cells, recombinant interleukin-6 alone was sufficient to activate both inducible elements.

Base Sequence↗
PubMed1990

Paraquat-resistant cell lines derived from Chinese hamster ovary cells.

Two paraquat-resistant clones, PR-1 and PR-2, were selected from CHO K1 cells pretreated with ethyl methanesulfonate. PR-1 and PR-2, routinely cultured in a normal medium without paraquat, were six fold more resistant to paraquat than the parental CHO K1 cells. There was no difference in the uptake of [3H]paraquat among PR-1, PR-2, and CHO K1 cells. Both PR-1 and PR-2 cells showed no cross resistance to free radical generating agents and no increase in total activity of superoxide dismutase. The activities of paraquat-dependent NADPH oxidase and glucose-6-phosphate dehydrogenase were significantly reduced in PR-1 and PR-2 cells, hence the rate of paraquat radical formation will be limited. In addition, an elevation of glutathione levels in PR-1 cells or an increase in glutathione S-transferase activity in PR-2 cells may also play a certain role in protective mechanisms against the toxicity of paraquat.

Animals↗
PubMed1990

[An approach to the mode of case findings of pulmonary tuberculosis in countryside].

Through basic health care network, the mode of symptomatic case finding was adopted to discover, treat and supervise pulmonary tuberculosis patients in countryside. The results showed that its outstanding advantages were high detection rate (13.2%), high proportion of initial treated cases (98.2%), high curative effect and low expenses. The detection rate of smear-positive patients (48.5%) was much higher than that of other case finding modes (P less than 0.05). Sputum conversion was seen in all smear positive cases. They were cured after regular treatment.

Diagnostic Services↗
PubMed1990

Prediction of fatty liver from serum triglyceride levels and body weight indexes.

Fatty liver is a common disease in Taiwan. In this study, we tried to evaluate the validity of predicting the presence of fatty liver from clinical data instead of liver biopsy or sonography. From a community survey in Putai, a total of 873 adults older than 30 years and quantified as to triglyceride level, body height, body weight, and the results of the oral glucose tolerance test and upper abdominal sonography were recruited for analysis. Using a receiver operating characteristic (ROC) curve, the best 'cutoff values' for determination of fatty liver were predicted from body weight index and serum triglyceride level in 8 clusters grouped by sex, age and presence or absence of diabetes mellitus. The best cutoff values of triglyceride in the 8 clusters varied from 100 to 170 mg/dl with worse validity. Most of the values were 130 and 140 mg/dl. The cutoff values of body weight index were constant in all clusters and showed greater validity than those for triglyceride. They were 115% or 120%. Their accuracy for the prediction of fatty liver was positively correlated with its prevalence. However, their accuracy was lower than 70% in non-diabetic females. We conclude that body weight index is a good parameter for prediction of fatty liver especially in the high risk groups and we recommend that health-determining cutoff values of serum triglyceride and body weight index should be set at 130 mg/dl and 115%, respectively.

Adult↗
PubMed1990

Specific high-affinity binding of host cell proteins to the 3' region of rubella virus RNA.

Replication of rubella virus is initiated at the 3' end of the genomic RNA. An inverted repeat sequence of 12 nucleotides that is capable of forming a stem-loop structure is located at the 3' end of the RNA, 59 nucleotides upstream from the poly (A) tail. We screened the 158-bp region of the 3' end of the virus, including the stem-loop structure, for its ability to bind to host-cell proteins. Specific high-affinity binding of three cytosolic proteins with relative molecular masses (Mr) of 61, 63 and 68 kD to the stem-loop structure was observed by UV-induced covalent crosslinking. Altering the stem structure by removal of specific bases abolished the binding interactions. The binding of the host proteins is greatly increased after infection and coincides with the appearance of negative strand RNA synthesis. The increase in binding is dependent on new protein synthesis. The amount of the 61-kD protein that binds varies in uninfected cells and is maximal in cells that are in the stationary phase of growth. All binding activity could be abrogated by alkaline phosphatase treatment of cell lysates. A possible role of these host proteins in the replication of rubella virus is discussed.

Animals↗
PubMed1989

Hydrolysis of proteins and peptides in a hermetically sealed microcapillary tube: high recovery of labile amino acids.

A method for the hydrolysis of peptides and proteins in a hermetically sealed microcapillary tube has been developed. The method is based on the concept that oxidative degradation of labile amino acids during acid hydrolysis of proteins and peptides at high temperature can be reduced to a minimum by limiting the ratio of air to liquid (v/v, less than 1:10) in a microcapillary tube. Furthermore, the physical constraints imposed by the capillary tube will restrict the exposure of the protein solution to air at a very limited area at the meniscus of the liquid. This method eliminates the necessity of time-consuming sealing under vacuum and/or flushing with nitrogen to remove oxygen in the hydrolysis tube. High recovery of labile amino acids can be obtained in a reproducible manner. Because of the simplicity and high reproducibility of the method described, it could be the method of choice for the hydrolysis of protein and peptide intended for quantitative amino acid analysis. Performic acid oxidation is performed at 50 degrees C for 10 min instead of 4 to 20 h at 0 degrees C to achieve an equally good yield of cysteic acid and methionine sulfone from peptides and proteins.

Amino Acids↗
PubMed1989

Nucleotide sequence of the 24S subgenomic messenger RNA of a vaccine strain (HPV77) of rubella virus: comparison with a wild-type strain (M33).

A full-length cDNA clone for the 24S subgenomic mRNA of the vaccine strain (HPV77) of rubella virus has been isolated from a cDNA library made from the RNAs of infected cells. Starting from the first Met start codon, the 24S mRNA codes for a precursor protein of 1063 amino acids (aa). This precursor encodes a capsid protein of 300 aa, and two envelope proteins, E1 (481 aa) and E2 (282 aa). Both the E1 and E2 proteins are preceded by a stretch of 21 hydrophobic aa, characteristic of a signal peptide, and each has three putative glycosylation sites in the polypeptide chains. Comparison between the structural proteins of the vaccine and the wild-type (wt; M33) strains of rubella virus, revealed that the E2 protein of the vaccine strain differs, in its apparent Mr, by approx. 3 kDa, from the wt strain. The difference could be due to decreased glycosylation of the vaccine strain E2 protein, as revealed by [3H]mannose incorporation studies. Five single-aa changes in the structural proteins occurred during the attenuation process, one each in the capsid and the E1 protein and three in the E2 protein. The change of Thr-412----Ile in the E2 protein results in the loss of a putative glycosylation site at Asn-410, which offers a plausible explanation for decreased glycosylation of the E2 protein from the vaccine strain of rubella virus.

Amino Acid Sequence↗