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Biomedical subjects

W Y Liu

Publications and source records attributed to W Y Liu.

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

Partial restoration of inactivated ribosomes: role of the aldehyde group generated by RNA N-glycosidase in the sarcin/ricin domain of 28S rRNA in ribosome.

In this paper, we report more information on the important role of the aldehyde group in the sarcin/ricin domain of 28S rRNA in rat liver ribosome. We find D-amino acids, amino acid derivatives having free amino group and two polyamines can also partially restore the activity of cinnamomin-inactivated ribosomes. However, amino acid derivatives and a tripeptide with blocked amino group cannot. Neither sodium borohydride nor the L-amino acids can restore the activity of ribosomes inactivated by alpha-sarcin. These data demonstrate that partial restoration of the activity of the inactivated ribosome is indeed the result of the blockage of the aldehyde group. It reaches the conclusion that emergence of the active aldehyde group in the sarcin/ricin domain of 28S rRNA is one of factors that inactivate the ribosome for protein synthesis.

Aldehydes↗
PubMed1997

Effects of hydrostatic pressure on the activity of rat ribosome and cell-free translation system.

The effects of high hydrostatic pressure on the protein synthesis activity of rat liver ribosome and the reconstructed cell-free translation system were studied. The results indicated that the activity of the ribosome decreased with the increase in applied pressure and the activity was totally lost as pressure went up to 2,400 bar, but there was a plateau approximately from 300 to 1,200 bar where the activity only had a minor change. The activity of the cell-free translation system seems to be more sensitive to pressure. Its activity was entirely lost when the pressure was up to 900 bar. The activity of rat ribosome and the cell-free translation system treated by pressure below 900 bar could be almost completely restored by incubation after releasing the pressure, but could be partially restored at higher pressure.

Animals↗
PubMed1997

Topography of ribosomes and initiation complexes from rat liver as revealed by atomic force microscopy.

Atomic force microscopy (AFM) was used to image ribosomes and ribosomal subunits (60S, 40S and native 40S ribosomal subunits) isolated from rat liver. A variety of topographic images were obtained directly and found to be consistent with models established by other biophysical methods. In addition, the ternary complex of eIF-2 x GTP x Met-tRNA(i) and the 43S preinitiation complex have been discerned by AFM directly. Detailed information about the binding sites for eIF-1A, eIF-2, eIF-3, and Met-tRNA(i) on the 40S ribosomal subunit was derived from the AFM images. Finally, factors which may give rise to artifactual images, namely, convolution of the AFM tip on ribosomes, surface tension collapse effect and dehydration, are discussed. This work demonstrates that AFM is useful for imaging ribosomes and translational complexes and provides valuable information that can be used to complement other well-established techniques.

Animals↗
PubMed1997

Dynamic structure of the sarcin/ricin domain in rat 28S ribosomal RNA investigated by hybridization with oligodeoxynucleotide.

In the static state of the ribosome, its S/R domain is not accessible to a probe of 1 4-mer oligodeoxyribonucleotide complementary to the region. However, during the in vitro translation process, the probe can specifically hybridize with the region in ribosome and inhibit translation. It appears that the S/R domain is well-protected when the ribosome is in the static state. This site is partially exposed at some stage(s) of translation. These results indicate that the S/R domain is not a simple single-strand, but a reversibly dynamic structure.

Animals↗
PubMed1997

[Research on hydrokinetics of self-intermittent vaccum root canal drainage]

A hydrokinetically simulated sucking was made to study the self-intermittent vacuum drainage of the root canal.Results showed that due to the shape difference between diameters at the upper and lower parts of the canal,the high-speed air-flow at the lower-end opening can drain the fluid below the opening out while the lower-speed air-flow at the upper opening is not likely to make the saliva and see page in the oral cavity reenter the root cavity.The above mentioned are in conformity with the Bernoulli's equation.

Journal Article↗
PubMed1997

Primary aldosteronism due to unilateral adrenal hyperplasia: a case report.

Primary aldosteronism is one of the differential diagnosis of secondary hypertension. This is usually caused by an aldosterone producing adenoma or bilateral adrenal hyperplasia which comprise about 65% and 30% of the cases, respectively. However, less than 1% of primary aldosteronism is caused by unilateral adrenal hyperplasia which is a relatively rare subset of primary aldosteronism. The clinical and biochemical manifestations of the disorder are indistinguishable from aldosterone-producing tumor, and a definitive diagnosis can only be made by pathological finding. A 33-year-old male Chinese patient presented with hypertension, hypokalemia, metabolic alkalosis, and the hypersecretion of aldosterone associated with suppressed plasma renin activity which is a typical hallmark of primary aldosteronism. Image studies including both magnetic resonance imaging (MRI) and 131I NIP-59 scan as well as postural test suggested an aldosterone-producing tumor of the right adrenal gland. Unilateral adrenectomy and pathological examination of the right adrenal gland eventually proved a case of unilateral adrenal hyperplasia. Blood pressure, plasma potassium, aldosterone and renin activity levels returned to normal two weeks after operation and had remained normal at up to one year of follow up. In addition, a saline loading test showed normal suppression of plasma aldosterone level one year after the operation, suggesting that the function of the left adrenal gland remains normal. The etiology of unilateral adrenal hyperplasia is unclear and the future recurrence of the disease is possible. Long-term follow-up is necessary to ensure the cure of this disorder.

Adrenal Glands↗
PubMed1996

Characterization of the enzymatic mechanism of gamma-momorcharin, a novel ribosome-inactivating protein with lower molecular weight of 11,500 purified from the seeds of bitter gourd (Momordica charantia).

The enzymatic mechanism of a small ribosome-inactivating protein, gamma-momorcharin, purified from the seeds of Momordica charantia, has been characterized. By SDS-polyacrylamide and electrospray ionization mass spectrometry, its molecular weight was measured to be 11,500 daltons which is much lower than other RIPs known to date. It can inhibit the protein synthesis in the rabbit reticulocyte cell-free system with ID50 of 55 nM. When rat liver ribosome was incubated with gamma-momorcharin, a diagnostic RNA fragment appeared on the gel after rRNAs were treated with acid aniline. Sequencing of the RNA fragment indicates that the action site of gamma-momorcharin in 28S ribosomal RNA of rat liver is at a specific adenosine (position 4324), which is in a highly conserved loop of 28S rRNA.

Dose-Response Relationship, Drug↗
PubMed1996

A fluorescence-labeling method for sequencing small RNA on polyacrylamide gel.

A practical fluorescence-labeling method for sequencing small RNAs by the traditional 'direct read out' on polyacrylamide gel electrophoresis was established. The 3' terminus of RNA was oxidized into dialdehyde by sodium periodate and then labeled with fluorescein-5-thiosemicarbazide through the condensation reaction between carbazide and aldehyde. The fluorescence-labeled RNA was partially degraded enzymatically and fractionated by polyacrylamide gel electrophoresis. The fluorescent bands were visualised by ultraviolet photography. A partial sequence of yeast 5S rRNA was determined. The result indicates that this method can be used in sequencing small RNAs rapidly, conveniently and safely.

Electrophoresis, Polyacrylamide Gel↗
PubMed1996

Cytotoxicity of two new ribosome-inactivating proteins, cinnamomin and camphorin, to carcinoma cells.

Cinnamomin (two-chain) and camphorin (single-chain), two novel ribosome-inactivating proteins (RIPs) purified from the seeds of Cinnamomum camphora, produced inhibitory effects in cultured carcinoma cells. The IC50 of cinnamomin to the human hepatocarcinoma cell-line 7721 and the melanoma cell-line M21 were 18.8 nmol and 11.7 nmol respectively. The IC50 of camphorin to the human hepatocarcinoma cell-line 7721 was 59 nmol, whereas the melanoma cell-line M21 was not susceptible to camphorin. Furthermore, cinnamomin exhibited a remarkable inhibitory effect on the growth of solid melanoma in the skin of the nude mouse. An R-fragment could be isolated from ribosomes of cinnamomin- or camphorin-treated carcinoma cells after incubation with acidic aniline, indicating that the cytotoxicity of these two new RIPs to carcinoma cells might result from modification to the ribosomes.

Algal Proteins↗
PubMed1996

Purification of a new ribosome-inactivating protein from the seeds of Cinnamomum porrectum and characterization of the RNA N-glycosidase activity of the toxic protein.

Porrectin, a new type II ribosome-inactivating protein (RIP), was purified from the seeds of the camphor tree (Cinnamomum porrectum) by affinity chromatography on acid-treated Sepharose 4B. Porrectin is a glycoprotein (M(r)64,500, sugar content 2.5%) consisting of an A-chain (M(r)30,500) and a B-chain (M(r)33,500) linked by the disulfide bond. The terminal sugar of glycan in porrectin B-chain is determined to be mannose. By non-denaturing polyacrylamide gel electrophoresis, porrectin displayed three isoforms that have different pl values with the same molecular weight. Porrectin is a potent inhibitor of eukaryotic protein synthesis in the rabbit reticulocyte lysate system. The molecular mechanism of action of porrectin on rat liver ribosomes is demonstrated to be specific for RNA N-glycosidase. The cleavage site is the adenosine at position 4324 (rat liver 28S rRNA) embedded in the highly conserved ricin/alpha-sarcin ('R/S') domain.

Algal Proteins↗
PubMed1995

Simultaneous existence of two types of ribosome-inactivating proteins in the seeds of Cinnamonum camphora--characterization of the enzymatic activities of these cytotoxic proteins.

Two types of ribosome-inactivating proteins (RIPs), camphorin and cinnamomin, have been purified from the seeds of Cinnamomum camphora. Camphorin is a type I RIP with a molecular mass of 23 kDa. Cinnamomin is a type II RIP having three isoforms, its molecular mass is around 61 kDa. The A- and B-chain derived from cinnamomin isoforms have similar mobilities in SDS-polyacrylamide gel. Camphorin and cinnamomin are both glycoproteins. In phylogenesis, it is particularly significant to find the simultaneous existence of type I and type II RIP as well as three isoforms of the latter in the same organ of a higher plant. The molecular mechanism of action of these two RIPs on mammalian ribosomes was demonstrated to be the specific RNA N-glycosidase activity. They modify 28S RNA among the four species of ribosomal RNAs. The cleavage site is the adenosine at position 4324 (rat liver 28S rRNA) embedded in the highly conserved 'R/S domain'. It is the first report that an intact type II RIP (cinnamomin) exhibits RNA N-glycosidase activity. Additionally, camphorin and cinnamomin can cleave supercoiled double-stranded DNA into nicked and linear forms (Ling et al. (1994) FEBS Lett. 345, 143-146).

Algal Proteins↗
PubMed1995

Partial restoration of inactivated ribosomes with sodium borohydride or amino acids.

The aldehyde radical of ribose C1' at position 4324 in rat liver 28S rRNA generated by RNA N-glycosidase was either reduced to an hydroxyl group by sodium borohydride or converted into aldimine through a nucleophilic addition of amino acid used as a primary amine. Analysis of the R-fragment of 28S rRNA by polyacrylamide gel electrophoresis showed that the reduction of aldehyde to an hydroxyl group with sodium borohydride was highly specific. The protein synthesis activity of modified ribosomes was partially restored with the removal of the active aldehyde by sodium borohydride or amino acid. Reduction of aldehyde with sodium borohydride restored 43.1% of the protein synthesis activity. Among the twenty natural amino acids tested, tryptophan and histidine could restore 57.4% and 42.1% of the ribosome activity when brome mosaic virus RNA was used as mRNA. We came to the conclusion that the active aldehyde radical at position 4324 of 28S rRNA in modified ribosome may cause the inactivation of the ribosome for protein synthesis.

Algal Proteins↗
PubMed1995

Isolation and characterization of a tyrosinase from the skin of the white silky fowl (Gallina lanigera) employing copper saturated diethylaminoethyl-cellulose.

Tyrosinase was purified to apparent homogeneity from the skin of the White Silky fowl (Gallina lanigera). Under alkaline conditions copper ions from a complex with the diethylaminoethyl moiety of DEAE-cellulose, allowing the purification of the enzyme in a one step chromatography. In polyacrylamide gel electrophoresis containing sodium dodecyl sulfate the purified tyrosinase displays a single band with a relative molecular mass of 66,000 Da. The crystalline tyrosinase was obtained from 32-33% saturated solution of ammonium sulfate. The enzyme catalyzes the o-hydroxylation of L-tyrosine to L-dihydroxyphenylalanine as well as the oxidation of pyrocatechol to o-benzoquinone. For the pyrocatechol oxidation the Michaelis Menten constant Km, is calculated to be around 1.19 x 10(-3) M.

Animals↗
PubMed1995

The interaction between "R/S domain" of rat 28S ribosomal RNA and ribosome-inactivating proteins investigated by fusidic acid.

The interaction between "R/S domain" of rat 28S rRNA and ribosome-inactivating proteins (RIPs) has been studied by blocking the action site of RIPs on "R/S domain" of 28S rRNA with fusidic acid or S100. Fusidic acid alone could form stable complexes with rat ribosomes and block the action site of RNA N-glycosidases. incubation of fusidic acid and S100 or GDP with ribosomes could also protect ribosomes from the action of ricin A-chain. However, different effect of fusidic acid, S100 an dGDP was observed when alpha-sarcin was used. Fusidic acid alone could not block the action site of alpha-sarcin. Fusidic acid together with the elongation factors in S100 could block the action site of alpha-sarcin. These results are consistent with the previous report that ricin A-chain and alpha-sarcin recognized different conformation of "R/S domain" in rat 28S rRNA.

Animals↗
PubMed1995

[Survey of disease of cultural shrimp in Taiwan].

The large number of hemocytes infiltrated several abnormal tissues of kuruma shrimp (Penaeus japonicus), including musculature, hepatopancreas, lymphoid organ, gill filament and sponge tissue. In addition, there were many denatured hemocytes existing inside acidophilic particles and forming granules. Futhermore, in hepatopancreas of kuruma shrimp, a white spot baculovirus (WSBV; 40-50 x 50-300 nm) was discovered in UH (undifferential haemocyte). The epithelium cells, which including stomach cuticle and underlying epidermis of exoskeletal cuticle, could also be infected by WSBV in another main cultural species--grass shrimp (P. monodon). During a period of high water temperature, with pond shrimp in normal condition, the CFU/ml of water bacteria rose from 10(5) to 10(7), but this number had decreased to 10(5) CFU/ml by the time moribund shrimp began to appear. Coincidentally, the total bacterial number isolated from hepatopancreas and musculature of moribound shrimp was over 10(5) (CFU/g) and 10(3)-10(5), respectively. The fauna of bacteria was taken over by the active metabolitic species which were represented by Vibrio species causing the pond shrimp to undergo either behavioral changes, such as swimming on the water surface, or histological changes, such as having whitish muscle color, hemocyte infiltration and granuloma formation etc. Pathogenetic species of Vibrio including V. parahaemolyticus, V. alginoly ticus V. anguillarum, V. fischery and V. damsela were isolated from those tissues of moribund shrimp. The main pathogens, isolated from musculature and hepatopancreas, were V. parahaemolyticus and V. alginolyticus. On the other hand there, was no bacterium could be isolated from the musculature of healthy shrimp and only a single species of Gram (+) coccus--Micrococcus--was isolated from the tissue of hepatopancreas.

Animals↗
PubMed1994

Cleavage of supercoiled double-stranded DNA by several ribosome-inactivating proteins in vitro.

Several ribosome-inactivating proteins (RIPs), such as ricin (including its A-chain), luffin, cinnamomin and camphorin, were found to express enzymatic activity to cleave supercoiled double-stranded DNA. In particular, alpha-sarcin, a RIP with a novel ribonuclease activity, was first proved to have this activity. They convert supercoiled DNA into a nicked circular conformation at low concentrations and further into a linear form at high concentrations: they have no effect on linear DNA. Although intact type II RIPs exhibited no RNA N-glucosidase activity, they were detected to cleave supercoiled DNA. Even if ricin A-chain was treated by boiling, its activity on supercoiled DNA was largely retained.

Animals↗
PubMed1994

Effect of arginase on splenic killer cell activity in patients with gastric cancer.

Arginase has been detected in high levels in gastric cancer tissues. The effect of arginase on the activities of splenic natural killer (NK) cell, phytohemagglutinin activated killer (PAK) cell, and interleukin-2 activated killer (LAK) cell in patients with gastric cancer (N = 12) was evaluated in vitro. These activities in patients (N = 10) with trauma and benign lesions were used as control. The splenic NK and PAK cell activities in patients with gastric cancer were significantly lower than in the controls (P < 0.05), whereas LAK cell activity did not have significant difference. Arginase inhibited all splenic killer cell activities to a similar degree between patients with gastric cancer and the controls. The inhibition was dose-related. These data suggest that arginase may play a positive role in the spread of gastric cancer cells. However, LAK may be a potential approach of immunoadoptive therapy in the future.

Arginase↗