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Biomedical subjects

B Dong

Publications and source records attributed to B Dong.

At least 55 records · Page 3Linked to original sources
PubMed1996

Erythropoietin-like activity in vivo of the fusion protein rhIL-6/IL-2 (CH925).

CH925 is a novel cytokine of a fusion protein interleukin-6 (IL-6)/IL-2 exhibiting erythropoietin (Epo)-like effects in vivo and ex vivo, in addition to its enhanced effects compared to IL-2 and IL-6 reported by us previously, which indicates its potential clinical use. Our present study was undertaken to determine the Epo-like activity of CH925 in vivo. The reticulocyte response was observed in transfusion-induced polycythemic mice by using flow cytometry with pyronin Y staining. On day 2 after injection of CH925, the average number of reticulocytes was 2.11% in the group given 250 micrograms/kg/d and 1.01% for 100 micrograms/kg/d. The mean fluorescence intensity (MFI) also significantly increased. Longitudinal studies of CH925 were performed on days 2, 4, and 10, and reticulocyte counts increased up to a peak on day 4. Activity of CH925 (100 micrograms/kg/d) corresponds to 1 U of standard rhEpo in our study.

Animals↗
PubMed1996

[US-guided microwave in the treatment of liver cancer: experimental study and preliminary clinical application].

OBJECTIVE: To completely coagulate deep tumor and protect normal tissue by using microwave electrode is vivo and in vitro animal experimental study, under US-guided percutaneous microwave coagulation. METHOD: The Ultrasound Microwave Therapy-I (UMT-I) equipment was utilized at 2450 MHz in frequency. RESULTS: Microwave coagulation could produce a stable necrosis area of 2cm in diameter with irradiation at 60-80W for 60-180 seconds, and the corresponding temperature at its surrounding area was 61.95 +/- 5.81 degrees C. Microwave induced coagulation of tumor correlated well with the sonographic changes. The shape of coagulated area was elliptic when 27 mm or 9 mm of the inner conductor of electrode was exposed, and the temperature of the shaft of the electrode raised smaller and slowly based on our animal experimental study, 15 nodules of 12 patients with liver cancer were microwave-coagulated under US-guide. The temperature of tumor surrounding area raised to 54-69.5 degrees C during operation. After treatment, all lesions had smaller size, hypoechogenicity and disappearance of blood flow. AFP titer dropped in 7 patients and normalized in 4. CONCLUSION: US-guided microwave for the treatment of liver cancer is effective in coagulating deep tumor and protecting normal tissue.

Animals↗
PubMed1995

Synthesis and biological activities of a phosphorodithioate analog of 2',5'-oligoadenylate.

To enhance the resistance of 2-5A (pppA2'p5'A2'p5'A) to degradation by exo- and endonucleases, a phosphorodithioate analog was synthesized using a solid-phase phosphite triester approach with N6-benzoyl-5'-O-dimethoxytrityl-3'-O-t-butyldimethylsilyladenosine 2'-[S-(beta-thiobenzoylethyl)-pyrrolidinophosphorothioamidit e]. 5'-Monophosphorylation was accomplished with 2-[2-(4,4'-dimethoxytrityloxy)-ethylsulfonyl]ethyl-(2-cyanoe thyl)-(N,N- diisopropyl)-phosphoramidite. The resulting product, p5'A2'(s2p)- 5'A2'(s2p)5'A, was approximately 10-fold less effective as an activator of purified human recombinant 2-5A-dependent RNase than was 2-5A itself. This loss of activation ability was related directly to the loss of binding ability of the phosphorodiothioate analog. As predicted, p5'A2'(s2p)5'A2' (s2p)5'A was stable to snake venom phosphodiesterase and the nucleolytic activities of both human lymphoblastoid CEM cell extracts and human serum, under conditions that led to facile degradation of parent 2-5A. This nuclease stability permitted the observation of the CEM cell extracts and human serum phosphatase activity which led to 5'-dephosphorylation of p5'A2'(s2p)5'A2'(s2p)5'A.

Adenine Nucleotides↗
PubMed1995

Catalytic cleavage of an RNA target by 2-5A antisense and RNase L.

2-5A antisense (2-5A-AS) molecules are chimeric oligonucleotides that cause 2-5A-dependent RNase (RNase L) to catalyze the selective cleavage of RNA in human cells. These composite nucleic acids consist of a 5'-monophosphorylated, 2',5'-linked oligoadenylate known as 2-5A (an activator of RNase L) covalently attached to antisense 3',5'-oligodeoxyribonucleotides. Here, we characterize the targeted cleavage of the double-stranded RNA-dependent protein kinase (PKR) mRNA by purified, recombinant human RNase L. A 2-5A-AS chimera, which contains complementary sequence to PKR mRNA, and unmodified 2-5A, which causes general RNA decay, were about 20- and 40-fold more active, respectively, than 2-5A-AS chimeras in which the DNA domains are not complementary to sequences in PKR mRNA. Directed cleavage was efficient because each 2-5A-AS chimera targeted many RNA molecules. Moreover, RNase L caused the catalytic cleavage of the RNA target (kcat of approximately 7 s-1). The precise sites of PKR mRNA cleavage caused by 2-5A-AS were mapped, using a primer extension assay, to phosphodiester bonds adjacent to the 3' terminus of the chimera binding site (5' on the RNA target) as well as within the chimera's oligonucleotide binding site itself. The selectivity of this approach is shown to be provided by the antisense arm of the chimera, which places the RNA target in close proximity to the RNase.

Base Sequence↗
PubMed1995

2-5A-dependent RNase molecules dimerize during activation by 2-5A.

2-5A-dependent RNase is an interferon-inducible enzyme that requires 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A) for its endoribonuclease activity against single-stranded RNAs. We demonstrate here that recombinant, human 2-5A-dependent RNase forms stable homodimers during its stimulation by 2-5A. The protein dimers were observed to form only upon binding to 2-5A, as shown using gel filtration chromatography and chemical cross-linking and after centrifugation in glycerol gradients. A monoclonal antibody to 2-5A-dependent RNase was prepared and used to probe the subunit structure of the enzyme in the presence or absence of 2-5A. Using oligoadenylates of different length, structure, and 5'-phosphorylation states we determined that conversion of 2-5A-dependent RNase from its monomeric, inactive form to its homodimeric, active form required the presence of functional 2-5A. These results demonstrate that the catalytically active form of 2-5A-dependent RNase is a homodimer.

Adenine Nucleotides↗
PubMed1995

A new method for early diagnosis of carcinoma in bile duct-sonography of common bile duct before and after injection of ceosunin.

42 cases of dilatation (7-15 mm) of extrahepatic bile duct after ceosunin injection (cholagogic method) were observed ultrasonographically. Among the 18 cases of testified obstructive lesions of the bile duct, 13 (72%) showed widening of the bile duct with an increase of calibre from 9.8 mm to 11.7 mm, 3 (16%) had no obvious change, and 2 (12%) shrank. Among the 24 cases of non-obstruction 22 (92%) shrank with a decrease calibre from 9.6 mm to 6.3 mm, and 2 (8%) showed no obvious change. After receiving cholagogue, 9 cases of periampullary carcinoma in the obstructive group were confronted with widening of the bile duct calibre. After longitudinal and transverse rotation scanning method was used, 8 of the 9 cases had their tumor mass visualized. Combined cholagogic and rotation scanning methods raised the lesion manifestation rate of lower bile duct from 41% to 88%. A dilated bile duct unable to show shrinkage of calibre after cholagogue injection is believed to be a criterion for judging the presence of a suspicious case of bile duct obstruction. This criterion has a sensitivity of 89%, specificity of 92%, and accuracy of 90%.

Adenocarcinoma↗
PubMed1995

[Clinical significance of detection of plasma fibronectin in respiratory failure].

Plasma fibronectin (PFn) level was measured with immumoelectrophoresis in 40 healthy adults and 174 patients (221 person-times) with respiratory insufficiency (R I). The levels of PFn in 40 healthy adults, 85 person-times of R I, 27 person-times of Type I respiratory failure (RF I), 82 person-times of RF II, and 27 person-times of iatrogenic RF (IRF) were 292.48 +/- 43.11 mg/L, 253.12 +/- 67.00 mg/L 141.97 +/- 70.84 mg/L, 180.48 +/- 49.96 mg/L and 263.49 +/- 70.05 mg/L respectively. The levels of PFn of patients with R I, RF I and RF II were significantly lower than that in healthy adults (P < 0.001). The level of PFn of patients with TRF was significantly lower than that in healthy adults (P < 0.05). There was positive correlation between the levels of PFn and PaO2 in 221 person-times of R I (r = 0.5358, P < 0.001), RF I r = 0.3822, P < 0.05). RF II (r = 0.3050, P < 0.01), and IRF (r = 0.4963, P < 0.02). There was negative correlation between the levels of PFn and PaCO2 in 221 person-times of R I (r = -0.2053, P < 0.005) and RF II (r = -0.2181, P < 0.05). In 34 patients with RF, the PFn before treatment was significantly lower than that two weeks after treatment (147.80 +/0 61.59 mg/L vs 214.56 +/- 56.12 mg/L) (P < 0.001). Among 33 cases of RF whose level of PFn was < 150 mg/L, 18 cases complicated multiple system organ failure and 4 cases complicated adult respiratory distress syndrome. The average level of PFn in 3 death cases was lower than 100 mg/L. It is suggested that PFn level might be used as an index in making early diagnosis, monitoring RF and predicating progosis of RF.

Adolescent↗
PubMed1995

[Preliminary study on change of interleukin-2 and its receptor in the elderly].

We measured the interleukin-2 (IL-2) and soluble interleukin-2 receptor (SIL-2R) in 86 senile patients (aged 71.5 +/- 8.45) with various diseases in order to evaluate the cell immune function in the elderly. The results showed that serum IL-2 activity was significantly lower in the senile group than in the middle-aged and young group, but SIL-2R was significantly higher in the senile group, predominantly in the cases of tumor and diabetes. It was also noted that lowered IL-2 activity and abnormal elevation of SIL-2R in late stage and diffused metastatic tumour patients were more significant than in other groups of senile patients. The magnitude of decrease in IL-2 activity and increase in SIL-2R correlated well with the severity of spread of tumour, suggesting that the higher the SIL-2R level goes, the worse the prognosis may be.

Aged↗
PubMed1995

[Experimental study of internal radiation with yttrium-90 microspheres in the treatment of mouse transplanted hepatoma].

The effect of yttrium-90 microspheres in the treatment of mouse transplanted hepatoma H22 was studied. Seventy BALB/C mice with hepatoma H22 were randomly divided into 7 groups (A, B, C, D, E, F, G) and treated respectively with 37, 18.5, 14.8, 11.1, 7.4, 3.7 and 0 MBq/cm3 internal radiation by intratumoral injection of Y-90 microspheres. Dose-dependent therapeutic effects were observed. In group A and B, the tumor growth was markedly retarded and eventually un-palpable. Histological examinations showed complete necrosis of the tumor. In groups C,D, E,F, the tumor growth was also inhibited. However, patchy necrosis could be seen amid apparently normal tumor cells. Only isolated, spotty foci of necrosis were present in the untreated control tumors. The results indicate that a tumor of 1 cm diameter can be effectively treated by internal radiation with 18.5MBq Y-90 microspheres injected into the tumor.

Animals↗
PubMed1995

[The changes in collagen contents and its clinical significance in chronic obstructive pulmonary disease].

Type III procollagen (P IIIP) hyaluronic acid (HA) and fibronectin (Fn) were assayed in patients with COPD, with radio-immunoassay (RIA). The results were shown as follows: The mean levels of P IIIP, HA were significantly higher than those of normal (P < 0.05, < 0.05). Plasma Fn was consistantly in lower level in COPD (P < 0.05). It is suggested that P IIIP, HA and Fn played a role in development of pulmonary fibrosis and quantification of such collagen contents may be a sensitive index to assess the degree of pulmonary fibrosis and to predict the prognosis of patients with COPD.

Aged↗
PubMed1995

Elevated levels of 2',5'-linked oligoadenylate-dependent ribonuclease L occur as an early event in colorectal tumorigenesis.

RNA decay in IFN-treated cells is controlled by 2'5'-linked oligoadenylate (2-5A)-dependent RNase (RNase L), a uniquely regulated endoribonuclease that requires short 5'-phosphorylated, 2-5A for its activity. Because RNase L is also implicated in the regulation of cell proliferation, we monitored its expression in colorectal adenocarcinomas and noncancerous polyps from familial adenomatous polyposis patients. Elevated levels of RNase L mRNA and activity were found in 17 of 20 tumors compared with corresponding normal mucosa. An mAb against RNase L revealed elevated amounts of this RNase in sections of the tumors, largely in the base of the villi. The occurrence of elevated levels of RNase L seems to be an early event in colorectal tumorigenesis, suggesting that control of RNA turnover is an important step in tumor progression. These data also indicate that regulating RNase L activity may be a useful strategy in treating colorectal carcinomas.

Adenocarcinoma↗
PubMed1994

Blockage of NF-kappa B signaling by selective ablation of an mRNA target by 2-5A antisense chimeras.

Activation of 2-5A-dependent ribonuclease by 5'-phosphorylated, 2',5'-linked oligoadenylates, known as 2-5A, is one pathway of interferon action. Unaided uptake into HeLa cells of 2-5A linked to an antisense oligonucleotide resulted in the selective ablation of messenger RNA for the double-stranded RNA (dsRNA)-dependent protein kinase PKR. Similarly, purified, recombinant human 2-5A-dependent ribonuclease was induced to selectively cleave PKR messenger RNA. Cells depleted of PKR activity were unresponsive to activation of nuclear factor-kappa B (NF-kappa B) by the dsRNA poly(I):poly(C), which provides direct evidence that PKR is a transducer for the dsRNA signaling of NF-kappa B.

Adenine Nucleotides↗
PubMed1994

Intrinsic molecular activities of the interferon-induced 2-5A-dependent RNase.

2-5A-dependent RNase (RNase L), a unique endoribonuclease that requires 5'-phosphorylated 2',5'-linked oligoadenylates (2-5A), functions in the molecular mechanism of interferon action. Because this enzyme is present at very low levels in nature, characterization and analysis have been limited. The molecular cloning of human, 2-5A-dependent RNase cDNA has facilitated its expression to high levels in insect cells by infecting with recombinant baculovirus. To determine the properties of the enzyme in the absence of other proteins, the recombinant 2-5A-dependent RNase was purified to homogeneity. The purified enzyme migrated as a monomer upon gel filtration in the absence of activator and showed highly specific, 2-5A-dependent RNase activity. The precise activator requirements were determined by stimulating the purified enzyme with a variety of 2',5'-linked oligonucleotides. The activated enzyme was capable of cleaving poly(rU) and, to a lesser extent, poly(rA), to sets of discrete products ranging from between 4 and 22 nucleotides in length. Reduced rates of 2-5A-dependent RNA cleavage were observed even after removal of ATP and chelation of divalent cations. However, optimal RNA cleavage rates required the presence of either manganese or magnesium and ATP.

Adenosine Triphosphate↗
PubMed1994

[A study on the proliferative and sclerosing mechanism of glomerular mesangium].

The role of glomerular mesangial cells (MC) and mesangial matrix (MM) in glomerular sclerosis was studied by using rat mesangial cell culture, immunohistochemical studies for laminin, laminin receptors as well as collagen types IV and III. The effect of tumor necrosis factor (TNF) and endothelin (ET) on MC was also studied. Results show that TNF and ET have potent mitogenic effects on MC. The glomerular MC possess the special capability of secreting TNF and ET. TNF and ET can also influence and induce the secretion of each other. The MM is increased in the MC nodular colonies formed after prolonged culture. These colonies are composed of collagen IV and collagen III. Therefore, injuring factors can cause MC and MM to proliferate and produce glomerulosclerosis.

Animals↗
PubMed1993

Purification and cDNA cloning of HeLa cell p54nrb, a nuclear protein with two RNA recognition motifs and extensive homology to human splicing factor PSF and Drosophila NONA/BJ6.

While searching for a human homolog of the S.cerevisiae splicing factor PRP18, we found a polypeptide that reacted strongly with antibodies against PRP18. We purified this polypeptide from HeLa cells using a Western blot assay, and named it p54nrb (for nuclear RNA-binding protein, 54 kDa). cDNAs encoding p54nrb were cloned with probes derived from partial sequence of the purified protein. These cDNAs have identical coding sequences but differ as a result of alternative splicing in the 5' untranslated region. The cDNAs encode a 471 aa polypeptide that contains two RNA recognition motifs (RRMs). Human p54nrb has no homology to yeast PRP18, except for a common epitope, but is instead 71% identical to human splicing factor PSF within a 320 aa region that includes both RRMs. In addition, both p54nrb and PSF are rich in Pro and Gln residues outside the main homology region. The Drosophila puff-specific protein BJ6, one of three products encoded by the alternatively spliced no-on-transient A gene (nonA), which is required for normal vision and courtship song, is 42% identical to p54nrb in the same 320 aa region. The striking homology between p54nrb, PSF, and NONA/BJ6 defines a novel phylogenetically conserved protein segment, termed DBHS domain (for Drosophila behavior, human splicing), which may be involved in regulating diverse pathways at the level of pre-mRNA splicing.

Amino Acid Sequence↗