Search PubMed⌕ Search

Biomedical subjects

J Zhu

Publications and source records attributed to J Zhu.

At least 685 records · Page 38Linked to original sources
PubMed1995

Effect of retinoic acid isomers on proliferation, differentiation and PML relocalization in the APL cell line NB4.

Retinoic acids exert a wide physiological role in development and differentiation. Retinoic acids have also been used in the treatment of human cancers, particularly in acute promyelocytic leukemia (APL). A structure-function relationship of the RA isomers in terms of clinical effect has been observed since all-trans retinoic acid (ATRA) induces a high complete remission rate while 13-cis retinoic acid (13-cis RA) shows much poorer effect. In this study, we examined the effect of RA isomers, including ATRA, 13-cis RA and 9-cis RA, on the proliferation and differentiation of NB4 cells. A number of parameters such as cell growth curve, dynamics of cell cycle, expression of clusters of differentiation and reduction of nitro blue tetrazolium (NBT) as well as immunofluorescence staining of PML were used to evaluate the effects of three isomers at two concentrations (10(-8) M and 10(-7) M). It has been shown that during the first 48 h of RA treatment, the APL cell differentiation was coupled with the cell proliferation. Although similar effects of proliferation inhibition and differentiation induction were observed among the three isomers at 10(-7) M, significant differences appeared at a concentration of 10(-8) M, 9-cis RA showed a higher activity than that of ATRA, while ATRA showed better results than 13-cis RA. Our results provide further evidence that 9-cis RA could be a promising molecule in differentiation induction of malignant cells.

Antigens, CD↗
PubMed1995

Taxol-induced mitotic block triggers rapid onset of a p53-independent apoptotic pathway.

BACKGROUND: At therapeutic concentrations, the antineoplastic agent taxol selectively perturbs mitotic spindle microtubules. Taxol has recently been shown to induce apoptosis, similar to the mechanism of cell death induced by other antineoplastic agents. However, taxol has shown efficacy against drug-refractory cancers, raising the possibility that this pharmacological agent may trigger an alternative apoptotic pathway. MATERIALS AND METHODS: The kinetics and IC50 of mitotic (M) block, aberrant mitosis, and cytotoxicity following taxol treatment were analyzed in human cell lines as well as normal mouse embryo fibroblasts (MEFs) and MEFs derived from p53-null mice. Apoptosis was followed by DNA gel electrophoresis and by in situ DNA end-labeling (TUNEL). RESULTS: Taxol induced two forms of cell cycle arrest: either directly in early M at prophase or, for those cells progressing through aberrant mitosis, arrest in G1 as multimininucleated cells. TUNEL labeling revealed that DNA nicking occurred within 30 min of the arrest in prophase. In contrast, G1-arrested, multimininucleated cells became TUNEL positive only after several days. In the subset of cells that became blocked directly in prophase, both wt p53-expressing and p53-null MEFs responded similarly to taxol, showing rapid onset of DNA nicking and apoptosis. However, p53-null MEFs progressing through aberrant mitosis failed to arrest in the subsequent G1 phase or to become TUNEL positive, and remained viable. CONCLUSIONS: Taxol induces two forms of cell cycle arrest, which in turn induce two independent apoptotic pathways. Arrest in prophase induces rapid onset of a p53-independent pathway, whereas G1-block and the resulting slow (3-5 days) apoptotic pathway are p53 dependent.

Animals↗
PubMed1995

[Inward rectifier potassium current in cultured embryonic chick ventricular myocytes and effect of culture time].

The single channel features of inward rectifier potassium current (IK1) in primary cultured embryonic chick ventricular myocytes and the effect of culture time on it were studied by using cell-attached patch clamp technique. The results showed that inward current fluctuation could be recorded at membrane potential negative to the potassium equilibrium potential (EK) and [K+] o = [K+]i = 140 mmol/L. The single channel current-voltage (I-V) relation was linear. The slope conductance was 35 pS (1-3 day culture). But at membrane potential positive to the EK, strong inward rectification was evident. The analysis of open and close time distribution indicated that a close-close-open three state model was appropriate to describe the gating processes of IK1 channel. No significant effect of culture time was observed. The channel density and slope conductance of IK1 were 0.64, 0.76, 0.77 channels/microns and 35, 28, 37 pS corresponding to 1-3, 4-6, and 7-11 day culture period, respectively. This result could partially explain why action potential of cardiomyocytes did not change with culture time.

Animals↗
PubMed1995

Expression of human stem cell factor in the baculovirus expression system.

A partial cDNA of human Stem Cell Factor (SCF) was isolated and transferred into the genome of Bombyx Mori Nuclear Polyhedrosis Virus adjacent to the polyhedrin promoter. The soluble form of the SCF protein was expressed in Bombyx Mori cells and silkworm larvae and was secreted into the medium in an active state. The recombinant SCF was similar to natural SCF with respect to its interaction with monoclonal antibody and its synergistic biological activity in conjunction with colony-stimulating factor.

Baculoviridae↗
PubMed1995

Rumen involvement in sheep tannic acid metabolism.

Tannic acid (TA) metabolism was studied in sheep after p.o., intra-abomasal and i.p. administration. TA and its phenolic metabolites in ruminal fluid, abomasal fluid, plasma and urine were determined using high-performance liquid chromatography at various intervals post-dosing. After po administration, gallic acid (GA) and pyrogallol (PYR) were present in ruminal fluid and plasma, and GA, PYR and 4-O-methyl gallic acid (40MGA) were found in urine. The concentration of GA in ruminal fluid and urine gradually decreased after dosing, while PYR concentration continued to rise. By contrast, after intra-abomasal dosing, GA and ellagic acid (EA) as well as TA were found in abomasal fluid, GA, 40MGA, EA and TA were present in plasma, and GA, 40MGA and PYR were in urine. The latter 3 metabolites were also detected in the urine after ip administration of TA. The plasma concentration of TA after intra-abomasal administration was significantly correlated with liver necrosis, and PYR concentration in ruminal fluid following po administration was significantly correlated to blood methemoglobin level. It was concluded that the methemoglobinemia seen in sheep given TA po is caused by high levels of the phenolic metabolite PYR, which is produced in the rumen. Liver and kidney necrosis, seen in sheep given TA directly into the abomasum, appears caused by unmetabolized TA rather than by metabolites.

Abomasum↗
PubMed1995

[Electrophoretic analysis of the protein patterns of the nuclear transplant rabbit embryos].

The qualitative patterns of protein synthesis in nuclear transplant rabbit embryos were examined by SDS-polyacrylamide gel electrophoresis followed by silver staining. The results indicated that the qualitative pattern of several protein synthesis in NT embryos was very different from the protein pattern of donor morulae or recipient oocytes, and also not as the same as the protein pattern obtained from fertilized ova at pronuclear formation stage. After fertilization or nuclear transfer, several maternal proteins were no longer synthesized or decreased in the embryo, and some new bands were observed and several protein synthesis were increased obviously. The most intriguing aspect of this study was the observation that all major changes in the protein pattern took place after fertilization or nuclear transfer and were rather similar. It is suggested that the gene activities of the donor nucleus from rabbit morulae are reprogrammed by the oocyte cytoplasm in current nuclear transfer technology, but the reprogramming is incomplete. This paper stresses on the paternal effect during fertilization on gene expression in nuclear transplant rabbit embryos.

Animals↗
PubMed1995

[Plasma prostacyclin (PGI2) levels in peripheral venous, arterial and portal venous blood in cirrhotic patients with portal hypertension and their clinical implication].

Plasma levels of PGI2 were measured by radioimmunoassay in 20 consecutively admitted cirrhotic patients with portal hypertension from Aug. 1993 to Aug. 1994. It was found that cirrhotic patients with portal hypertension had much higher portal venous PGI2 levels than controls (528.25 +/- 205.48ng/L vs. 235.73 +/- 49.36ng/L, P < 0.001). Portal venous PGI2 levels in patients with cirrhosis and portal hypertension correlated significantly with portal venous pressure (r = 0.60, P < 0.05). The results indicate that increased portal venous PGI2 levels may have a role in maintenance of established portal hypertensive state in cirrhotic patients with portal hypertension.

Adult↗
PubMed1995

[Diagnosis and management on acute coronary artery occlusion in valve replacement surgery: a report of four cases].

This paper reported four cases of acute coronary artery occlusion occurred during valve replacement procedure. Case 1 was of Marfan's syndrome who underwent Cabrol procedure. Case 2 was of congenital aortic bileaflet malformation with severe regurgitation and simple right coronary artery, who received the procedure of AVR. Both cases 3 and 4 suffered from rheumatic valve disease who were given DVR and tricuspid valve annuloplasty. All the cases had acute left coronary artery occlusion and did not revive after removal of aortic cross-clamp, which were immediately corrected by coronary bapass grafts from aortic to left descending branch with saphonous veins. All the patients successfully weaned from asistant circulation. Two cases survived. The causes of acute coronary artery occlusion were analyzed and the diagnostic methods and management introduced.

Acute Disease↗
PubMed1994

Differential binding domains of peptide and non-peptide ligands in the cloned rat kappa opioid receptor.

This study was to identify specific regions in kappa opioid receptors that accounted for binding selectivity of kappa ligands. Six chimeric mu/kappa receptors were constructed from cloned rat kappa and mu opioid receptors and transiently expressed in COS-1 cells. All six chimeric mu/kappa receptors bound [3H] diprenorphine with high affinities, indicating that these chimeras retain opioid receptor conformation. Binding affinities of three peptide ligands (dynorphin A, alpha-neo-endorphin, and dynorphin B) and three nonpeptide ligands (norbinaltorphimine, U50,488H, and U69,593) for chimeras were determined and compared to those for mu and kappa opioid receptors. The second extracellular loop and the adjoining C-terminal portion of the fourth transmembrane helix were essential for the high affinity binding of dynorphin A, alpha-neo-endorphin, and dynorphin B to the kappa receptor. The third extracellular loop and the sixth and seventh transmembrane helices played an important role in determining the selectivity of nor-binaltorphimine for the kappa over the mu receptor. U50,488H and U69,593 appeared to require the whole kappa receptor except the second extracellular loop to attain high affinity binding. Thus, the kappa opioid receptor has differential binding domains for peptide and non-peptide ligands.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1994

Laparoscopy through the vaginal fornix of cows for the repeated aspiration of follicular oocytes.

A simple method is described for the repeated laparoscopic examination of the internal reproductive organs of cows and heifers through the vaginal fornix. It can be performed in a simple crush in less than 15 minutes, does not require surgery and can be used under field conditions. The method has been used for aspirating oocytes from follicles which were at least 2 mm in diameter in animals under sedation and epidural anaesthesia. In a preliminary study 11 cows and eight heifers were allocated into two groups: 12 animals were treated weekly with 500 iu pregnant mare's serum gonadotrophin and seven animals were not stimulated with gonadotrophin. The mean numbers of oocytes collected from the treated cows (6.3) and heifers (3.3) did not differ significantly from the numbers collected from the stimulated cows (5.5) and heifers (4.0). After the procedure had been established a mean oocyte collection rate of up to 75 per cent of follicles aspirated was obtained in 12 unstimulated heifers. When follicles were aspirated twice instead of once a week, the mean number of follicles observed (16.2 vs 7.0) and the mean number of oocytes collected per week (12.2 vs 5.2) were significantly higher (P < 0.05).

Animals↗
PubMed1994

Neuropeptide Y promotes GTP photo-incorporation into a 55 kDa protein.

Incubation of bovine hippocampal membranes with [alpha-32P]GTP and exposure to ultraviolet light resulted in the labelling of seven species with apparent molecular masses of 200, 74, 55, 53, 50, 43 and 40 kDa. Labelling of the 55 kDa species was greatly enhanced in the presence of carboxyl terminal fragments [neuropeptide Y-(18-36)] of neuropeptide Y. Labelling occurred with [alpha-32P]GTP but not [alpha-32P]ATP. A group of putative direct G protein activating peptides including mastoparan, melittin, substance P and adrenocorticotropic hormone (ACTH)-(1-24), were also able to stimulate the labelling of this protein. Labelling of the 55 kDa protein could be demonstrated in bovine brain but not peripheral tissues. Western blot analysis using an antibody against the common alpha subunit of G proteins recognized a protein co-migrating with the 55 kDa GTP-binding protein. These findings demonstrate the existence of a previously uncharacterized neuronal protein, with an apparent molecular mass of 55 kDa, that binds GTP in response to neuropeptide Y and other peptides.

Affinity Labels↗
PubMed1994

Three ARS elements contribute to the ura4 replication origin region in the fission yeast, Schizosaccharomyces pombe.

The ura4 replication origin region, which is located near the ura4 gene on chromosome III of the fission yeast, Schizosaccharomyces pombe, contains multiple initiation sites. We have used 2D gel electrophoretic replicon mapping methods to study the distribution of these initiation sites, and have found that they are concentrated near three ARS elements (stretches of DNA which permit autonomous plasmid replication). To determine the roles of these ARS elements in the function of the ura4 origin region, we deleted either one or two of them from the chromosome and then assessed the consequences of the deletions by 2D gel electrophoresis. The results suggest that each of the three ARS elements is responsible for the initiation events in its vicinity and that the ARS elements interfere with each other in a hierarchical fashion. It is possible that the large initiation zones of animal cells are similarly composed of multiple mutually interfering origins.

Chromosome Mapping↗
PubMed1994

A new UV-filter compound in human lenses.

A new UV-filter compound, 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-glucoside, has been identified in human lenses. The structure suggests that it is derived biosynthetically from tryptophan. Quantification studies on the new compound show that it is the second-most abundant UV-filter compound in the lens with an absorption and fluorescence spectrum similar to that of 3-hydroxykynurenine glucoside.

Chromatography, High Pressure Liquid↗
PubMed1994

Structural characterization of the N-glycans of a humanized anti-CD18 murine immunoglobulin G.

This study characterized the N-glycans of a humanized immunoglobulin G4 (IgG4) expressed in NS/O mouse myeloma cells and directed against the CD18 family of adhesion-promoting receptors on leukocytes. The N-glycans were released from the purified recombinant IgG by N-glycanase treatment, purified by Sephadex G50 chromatography, and fractionated by Bio-Gel P-4 chromatography into three oligosaccharide pools. Each pool was analyzed individually by glycosyl composition analysis, high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), 600-MHz 1H-NMR spectroscopy, and electrospray-ionization mass spectrometry. In addition, each of the three pools was subfractionated by HPAEC and the isolated subfractions that contained sufficient material were hydrolyzed and analyzed for glycosyl composition by HPAEC-PAD. The overall results indicate the presence of five oligomannoside-type structures (containing 5 to 8 Man residues) which are not usually found in IgG, and the presence of eight diantennary (mostly truncated) N-acetyllactosamine-type structures which are typical of mouse and human IgGs. The N-acetyllactosamine-type structures were heterogeneous with regard to alpha(1-->6) fucosylation of the linkage GlcNAc, and the presence or absence of GlcNAc and/or Gal beta(1-->4)GlcNAc extending the core pentasaccharide (Man3GlcNAc2). No evidence was found for the presence of sialic acid or bisecting GlcNAc residues on the N-acetyllactosamine-type chains. The latter finding suggests that the N-glycans of this humanized IgG are of the mouse type.

Animals↗
PubMed1994

Isolation and structure determination of terminalin A toxic condensed tannin from Terminalia oblongata.

Terminalia oblongata (yellow wood) is a small deciduous tree growing over an area of central Queensland that supports a large proportion of this state's cattle population. Cattle and sheep that consume yellow wood leaves are poisoned and die. Severe losses of these animals can occur, and this problem is considered the main cause of economic loss to the cattle industry in the area apart from drought. A new toxic condensed tannin, terminalin was isolated from Terminalia oblongata. Its structure was deduced following NMR, IR, UV, MS analyses and in the knowledge that these data show good correlations to those obtained from the related punicalagin molecule which is present in the plant. Terminalin has a high toxicity (20 mg/kg) to white Quackenbush male mice and produces a vascular renal necrosis with slight liver necrosis, unlike punicalagin, which produces liver lesions but not kidney lesions. Similar results were obtained with sheep. A most interesting aspect is that there are two different specific toxins in the plant.

Animals↗
PubMed1994

Peptide mapping of the subunits and deglycosylated polypeptides of human liver alpha-L-fucosidase.

The subunits of human liver alpha-L-fucosidase have been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, excised, and subjected to peptide mapping after CNBr cleavage or trypsin digestion. The CNBr peptide maps of the glycosylated 56- and 51-kDa subunits were similar except that the larger subunit had several peptides with M(r)s shifted higher than those apparent for the smaller subunit. These M(r) differences were almost completely eliminated when CNBr peptide mapping was performed on the deglycosylated 48- and 45-kDa polypeptides, suggesting that the M(r) differences were due to carbohydrate differences. Minor differences not related to glycosylation were found in the CNBr peptide maps for the 48- and 45-kDa polypeptides including the presence of small amounts of three peptides in the larger polypeptide not found in the smaller polypeptide. Sequence analysis suggested that both the 48- and the 45-kDa polypeptides were blocked at their amino-termini but analysis of the largest CNBr peptide from each polypeptide indicated an identical 13-amino-acid sequence corresponding to residues 6 through 18 from the cDNA-deduced sequence of mature alpha-L-fucosidase. Tryptic peptide mapping indicated very similar HPLC peptide profiles for the deglycosylated 48- and 45-kDa polypeptides except for the presence of small amounts of six peaks present in the larger polypeptide which were not detected in the smaller polypeptide. The overall results provide the first evidence that the polypeptides of human liver fucosidase are very similar and probably encoded by the same gene. However, minor differences in the polypeptides exist, possibly due to normal allelic variation, alternative splicing, proteolytic processing, and/or posttranslational modifications other than those due to glycosylation.

Amidohydrolases↗