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Biomedical subjects

D Zhu

Publications and source records attributed to D Zhu.

At least 253 records · Page 14Linked to original sources
PubMed1994

Differential induction of human monocyte transforming growth factor beta 1 production and its regulation by interleukin 4.

We have previously shown that trauma patients' monocytes which are in vivo activated by multiple injury-induced mediators have elevated transforming growth factor-beta (TGF beta) bioactivity. Interleukin-4 (IL-4), a Th2 and B lymphocyte stimulatory factor, has been shown to inhibit monocyte production of a number of mediators both after lipopolysaccharide stimulation and after trauma-induced stimulation. However, IL-4 inhibitory effects appears to vary, depending on the mixture of inducing stimuli. Here we describe the in vitro IL-4 inhibition of human monocyte TGF beta bioactivity using several stimulation induction protocols: muramyl dipeptide stimulation alone, or after Fc gamma RI (CD64) cross-linking induction, interferon-gamma (IFN gamma) priming, or trauma-generated in vivo mediator induction. IL-4 suppressed both muramyl dipeptide-induced TGF beta bioactivity and TGF beta mRNA in a dose-dependent fashion and was most effective when IL-4 was administered at initiation of normal monocyte stimulation. Muramyl dipeptide (MDP)-induced increases in trauma patients' monocyte TGF beta bioactivity were also inhibited by high doses of IL-4 (25 ng/ml). Fc gamma RI cross-linking increased MDP-induced normal monocyte TGF beta bioactivity, but this increase could be consistently inhibited only by very high IL-4 concentrations (50 ng/ml). IL-4 did not consistently downregulate MDP-induced TGF beta bioactivity in IFN gamma-primed monocytes. IL-4 can suppress monocyte TGF beta production, as well as other monocyte mediators, but its efficiency depends on the stimuli combination present in the microenvironment.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1994

Molecular genetic prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency by allele-specific hybridization.

The feasibility and accuracy of gene-specific molecular genetic diagnosis for congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency were studied in a group of 24 pregnancies at 25% risk of carrying an affected fetus. Chorionic villus sampling was performed in the majority of cases. Southern blot analysis was carried out to identify deletions or other gross rearrangements. In parallel, the polymerase chain reaction (PCR) was performed, followed by allele-specific oligonucleotide hybridization (ASO) for a panel of nine known mutations. Mutations were identified in 95% of the chromosomes examined. The molecular diagnosis was accurate in 23 of 24 infants. The most common mutation identified was an A-to-G transition in the second intron (52% of affected chromosomes), the result of an apparent gene conversion. One fetus carried homozygous deletion of CYP21, which accounted for 13% of all affected chromosomes. Other mutations identified included an 8-bp deletion in the third exon (22%); Ile172 to Asn, a nonconservative substitution, in the fourth exon (9%); and Gln318 to term, a nonsense mutation, in the eight exon (4%). No mutation was detected in CYP21 in 5% of obligate-affected chromosomes examined by these methods.

Adrenal Hyperplasia, Congenital↗
PubMed1994

Glomerular distribution of type IV collagen in diabetes by high resolution quantitative immunochemistry.

We examined type IV collagen distribution and density in human diabetic kidneys by quantitative immunogold electron microscopy. We studied normal kidney transplant donors and "slow-track" and "fast-track" insulin dependent diabetic (IDDM) patients. The "slow-track" patients had IDDM for > or = 20 years and mesangial volume fraction (VvMes/glom) of < or = 0.32. The "fast-track" patients had IDDM for < or = 20 years and VvMes/glom > or = 0.37. Renal biopsies were embedded in Lowicryl, reacted with polyclonal anti-type IV collagen (in the distribution of the classical alpha 1(IV) and alpha 2(IV) collagen chains) and monoclonal anti-alpha 4(IV) collagen chain antibody followed by gold conjugated secondary antibody. We found, by morphometric techniques, a decrease in the immunogold densities of anti-type IV collagen in the subendothelial zone of the GBM in the "fast-track" IDDM patients. There was a trend towards a decrease in mesangial matrix (MM) particle density in the "fast-track" (P = 0.07) but not in the "slow-track" patients. However, because of the marked increase in MM in the "fast-track" patients, the per glomerulus estimated quantity of these antigens in MM was increased. In contrast, the density of alpha 4(IV) collagen chain was increased in the epithelial zone of the GBM in the "fast-track" IDDM patients. It is not known whether these changes in glomerular type IV collagen represent markers of advanced diabetic lesions or whether these changes might be detected earlier in diabetic patients destined for the later development of serious lesions.

Adolescent↗
PubMed1994

Sequence evolution and phylogenetic signal in control-region and cytochrome b sequences of rainbow fishes (Melanotaeniidae).

The nucleotide sequences of segments of the cytochrome b gene (351 bp), the tRNA(Pro) gene (49 bp), and the control region (approximately 313 bp) of mitochondrial DNA were obtained from 26 fish representing different populations and species of Melanotaenia and one species of Glossolepis, freshwater rainbow fishes confined to Australia and New Guinea. The purpose was to investigate relative rates and patterns of sequence evolution. Overall levels of divergence were similar for the cytochrome b and tRNA control-region sequences, both ranging from < 1% within subspecies to 15%-19% between genera. However, the patterns of sequence evolution differed. For the cytochrome b gene, transitions consistently exceeded transversions, the bias ranging from 4.2:1 to 2:1, depending on the level of sequence divergence. However, in the control-region sequence, a bias toward transitions (2:1) was observed only in comparisons between very similar sequences, and transversions outnumbered transitions in comparisons of divergent sequences. Graphic comparisons suggested that the control region was saturated for transitions at relatively low levels of sequence divergence but accumulated transversions at a greater rate than did the cytochrome b sequence. These distinct patterns of base substitution are associated with differences in A+T content, which is 70% for the tRNA control-region segment versus 50% for cytochrome b. A test for skewness in the distribution of lengths of random trees indicated that both segments contained phylogenetic signal. Parsimony analyses of the data from the two regions, with or without weighting schemes appropriate to the respective patterns of sequence evolution, identified the same five groupings of sequences, but the relationships among the groups differed. However, in most cases the branches uniting different combinations of groups were poorly supported, and the differences among topologies were insignificant. Considering the observed patterns of base substitution and the results of the phylogenetic analyses, we deduce that both the control region and cytochrome b are appropriate for population genetic studies but that the control region is less effective than cytochrome b for resolving relationships among divergent lineages of rainbow fishes.

Animals↗
PubMed1994

Clonal history of a human follicular lymphoma as revealed in the immunoglobulin variable region genes.

The variable region genes used to encode the immunoglobulin expressed by tumour cells of a patient with follicular lymphoma have been identified and sequenced. Initially, a lymph node biopsy was analysed and revealed usage of VH and V kappa genes which had numerous substitutions as compared with the closest germ line genes. The pattern of mutations in VH was consistent with a role for positive selection by antigen. In addition, there was evidence in both VH and V kappa sequences for clonal heterogeneity. After 5 years, which included treatment with chemotherapy, the patient relapsed with tumour cells present in the blood. Analysis of the V-genes used by the emerging tumour revealed a single homogeneous sequence for both VH and VL, which, in each case, matched closely one of the sequences in the original lymph node biopsy. These results indicate that selection, possibly mediated by antigen, can operate on a cell destined to give rise to lymphoma, and that intraclonal variation can occur after the neoplastic event. However, in this case, late relapse in the blood is dominated by a single clone.

Amino Acid Sequence↗
PubMed1994

Application of electron microscopic immunocytochemistry to the human kidney: distribution of type IV and type VI collagen in normal human kidney.

We used immunogold electron microscopic (IEM) techniques with periodate-lysine-paraformaldehyde-fixed and Lowicryl-embedded or cryopreserved tissues to study the distribution of alpha 1(IV) and alpha 3(IV) chains of Types IV and VI collagen in glomerular basement membrane (GBM) and mesangial matrix of glomeruli in normal human kidneys. Monoclonal antibodies to alpha 1(IV) and alpha 3(IV) collagen chains and Type VI collagen could be detected only with cryoultramicrotomy, whereas polyclonal anti-Type IV collagen antibody was detectable in Lowicryl-embedded tissue. Ultrastructural detail was better preserved in the Lowicryl-embedded tissue. IEM labeling provided more detailed information as to the site-specific array of these extracellular matrix molecules in glomeruli than did immunofluorescent microscopy. The labeling of alpha 1(IV) collagen chain was distributed mainly along the endothelial side of glomerular basement membrane and the mesangial matrix. Mesangial GBM was relatively poorly labeled compared with that of mesangial matrix. In contrast, the alpha 3(IV) chain was detected throughout the thickness of the GBM, but there was no labeling of mesangial matrix. Type VI collagen distribution was identical to that of the alpha 1(IV) chain within the glomerulus but was also associated with interstitial collagen fibrils. This study documents and details the heterogeneous distribution of Type IV and VI collagen chains within the normal human glomerulus and provides the framework for the study of these matrix components in human glomerular diseases.

Basement Membrane↗
PubMed1994

Properties of three proteinases functioning at G1, S and G2 phases in HeLa cells and their inhibition by guanidino- and amidino-acid esters.

HeLa cells were synchronized by double thymidine-block and allowed to grow after removal of thymidine. Three proteinases, tryptase 17:17, proteinase In and late G2 proteinase, were prepared from the HeLa cells harvested at the time when each proteinase appeared in the cell cycle of the cells. All of them were suggested to be trypsin-like serine proteinases, because they hydrolyzed trypsin-specific fluorogenic substrates and their activities were inhibited by benzamidine, soybean trypsin inhibitor, leupeptin, tosyl-L-lysine chloromethan (TLCK) and diisopropylfluorophosphate (DEP). However, the actions of these proteinases on the substrates and inhibitors suggested that they were three different proteinases. They were strongly inhibited by 4-tert-butylphenyl and biphenyl esters of trans-4-guanidinomethylcyclohexanecarboxylic acid, amidinopiperidine-4-acetic and 4-propionic acids, which retard the second DNA synthetic (S) and mitotic (M) phases for 3h, 4-tert-butylphenyl ester of amidinopiperidin-4-carboxylic acid, which blocks initiation of S phase, the ester of amidinopiperidine-4-butyric acid, which suppresses the second S and M phases, and the esters of trans-4-amidinocyclohexanecarboxylic and 4-propionic acids which inhibit M phase.

Amino Acid Sequence↗
PubMed1994

Expression of biologically active monomeric form of human M-CSF in baculovirus infected silkworm, Bombyx mori.

The human macrophage colony stimulating factor (hM-CSF) in its monomeric form has been over-produced in BmN cells and in silkworm larvae infected with the recombinant baculovirus Bm284M-CSF. The recombinant monomeric M-CSF (rhM-CSF) exhibited the activity of 8-14 x 10(4) units/ml of cell culture medium. When the insect larvae were infected with the recombinant virus, the maximum rhM-CSF was expressed 4-5 days post infection with an activity of 3 x 10(6) units/ml hemolymph. The monomeric rhM-CSF was purified to homogeneity through three steps of purification. A pilot purification yielded 1 mg of homogeneous monomeric rhM-CSF from 10 larvae. The purified rhM-CSF monomers gradually dimerized in vitro. In contrast, the crude or the semi-purified monomers did not dimerize in vitro, indicating that the presence of an unknown moiety in the rhM-CSF preparations obtained from hemolymph interfered with dimerization.

Alkylation↗
PubMed1994

[Local recurrence after conservative therapy of breast cancer: risk factors, site of recurrence, evolution].

The identification of factors associated with breast recurrence as first event (62 cases, 10%) following conservative surgery and radiation therapy are drawn out from a series++ of 618 mammary carcinomas of clinical size less than 40 mm, stage I and II (UICC), with a median follow up of 8 years. The most powerful predictive characteristic associated with the likelihood of breast recurrence is multiple foci of invasion (42.9% vs 8.9, P = 0.0001, relative risk [RR]: 6). After this rarely cited feature, young age, less than 40 years (20% vs 7.3%, P = 0.0001, RR: 2.8), extensive in situ carcinoma more than 25% (19.2% vs 8.7%, P = 0.003, RR: 2.5) were found also persistent in the Cox model, but not histologic size more than 25 mm (18.9% vs 9.1%, P = 0.01, RR: 2.3). The site of recurrence was studied on the 54 salvage mastectomy done. A high rate of recurrence at distance of the initial site was found: 37% whose more than half, 22%, were multicentric. No significant difference in the mean delay of appearance was noted between recurrence near or at distance of the initial cancer (mean delay 52 months vs 64 months). From the recurrence the evolution is not very favourable: excluding simultaneous metastases found at the preoperative investigation, ten cases, mammary recurrence is followed by a metastatic syndrome in 36% of cases against 17% without it (P = 0.01, RR: 1.9). Metastatic evolution is not significantly linked with the time, early or late, of the mammary recurrence (54.5% before 5 years vs 39% after) but with the association of a controlateral cancer (P = 0.03). Locally ten of the 54 mastectomy presented a thoracic recurrence, often in case of multicentric breast recurrence (P = 0.05) and not significantly when skin or areola were invaded by carcinoma.

Adenocarcinoma↗
PubMed1994

Expression of a fibrinolytically active human pro-urokinase fusion protein in Escherichia coli.

The gene encoding human pro-urokinase(pro-UK) was cloned into plasmid pEZZ318 and fused to the gene coding for the signal peptide of staphylococcal protein A and IgG bindinging domain. The fusion protein which was synthesized under the control of T7 promoter in Escherichia coli and secreted into the growth medium, was found to be fibrinolytically active. Approximately 60% of the total activity was secreted into the culture medium, where levels of activity approached 150,000 I.U./liter and about 40% of the total activity remained in the cell lysate with levels of activity around 100,000 I.U./liter. The fusion protein was purified in a single step by IgG affinity chromatography. These results demonstrate that human pro-UK can be synthesized and secreted by E. coli as a fibrinolytically active fusion protein.

Binding Sites↗
PubMed1994

Expression of a biologically active human granulocyte-macrophage colony stimulating factor fusion protein in Escherichia coli.

A gene encoding human granulocyte-macrophage colony stimulating factor(GM-CSF), was cloned into plasmid pEZZ318 and fused to a DNA segment coding for the signal peptide of staphylococcal protein A and a synthetic gene coding for a protein with ability to bind immunoglobulin G(IgG). The fusion protein was expressed in Escherichia coli and biologically actively secreted into the growth medium. Approximately all of the total activity was secreted into the culture medium, where levels of activity approached 1.96 x 10(8) units/liter. Purification of the fusion protein was performed in a single step by affinity chromatography with immobilized IgG to a specific activity of 1.2 x 10(8) units/mg.

Escherichia coli↗
PubMed1994

[Soluble interleukin-2 receptor level in the sera and ascitic fluids in patients with ovarian cancer].

In 31 patients with ovarian cancer, the sIL-2R level of the sera and ascitic fluids were measured by ELISA, to investigate the inhibitive effect of sIL-2R purified from ascitic fluids on normal lymphocyte transformation, stimulated with phytohemagglutinin (PHA). The results showed that the sera sIL-2R levels in the patients were much higher than those in the normal controls (857 +/- 428kU/L vs 235 +/- 90kU/L, P < 0.001). The sera sIL-2R levels in mucinous cancer were significantly higher than those in serous cancer (988 +/- 539kU/L vs 488 +/- 233kU/L P < 0.01). But no obvious correlation was observed with the histopathological grading, nor with metastasis. Higher levels of sIL-2R were also observed in the ascitic. The normal lymphocyte transformation stimulated with PHA was significantly inhibited by high sIL-2R purified from the ascitic fluids.

Adult↗
PubMed1994

Expression and purification of a truncated macrophage colony stimulating factor in Kluyveromyces lactis.

A truncated human macrophage colony stimulating factor (M-CSF) cDNA encoding amino acid residues from 3 to 149 of the native M-CSF was obtained by using polymerase chain reaction. When inserted into plasmid pCXJ1 and psPHO5 and introduced into Kluyveromyces lactis, it directs the the secretory expression of the biologically active dimeric form of M-CSF. Through a four-step purification protocol, i.e. ammonium sulfate salting out, DEAE-cellulose column chromatography, hydrophobic chromatography on phenyl-sepharose and Mono Q fast protein liquid chromatography, the recombinant truncated M-CSF was purified to homogenerity and show its apparent molecular mass at 21KDa on reduced SDS-PAGE, with a specific activity of 1.21 x 10(7) units/mg protein.

Amino Acid Sequence↗
PubMed1994

[Study on influence degree of probability of endemic factors for schistosomiasis transmission in Yunnan mountainous regions].

In Zhonghe Village of Weishan County, Yunnan Province, a schistosomiasis endemic area of mountainous valley subtype, an epidemiological investigation was conducted on its natural, biological and social factors influencing schistosomiasis transmission in 1987-1990. The results were analyzed by stratified sampling analysis and probability accumulation method. It was demonstrated that 12 of 29 factors were the most important factors influencing schistosomiasis transmission including annual average air-temperature, number of infection sources, number of spots with infected snails, water temperature and annual average rainfall, etc. The values of influence degree before and after intervention measures were 3.513 and 2.066, respectively, the decrease being 41%.

Animals↗
PubMed1994

[Invasion of Drosophila albomicans into Shanghai and areas nearby and a study on its mitochondrial DNA polymorphism].

We report the fact that D. albomicans invaded into Shanghai suddenly in the autumn of 1991. Using 9 restriction enzymes, we analyse the RFLPs of mitochondrial DNA of 29 isofemale lines belonging to 4 populations of Shanghai, Jiading, Qinpu and Nanhui. We find that all 29 haplotypes are different from each other. Comparing with the populations of Canton, Kunming, Sanhutan (Taiwan), Sumoto (Japan), and Kuala Lumper (Malaysia), we come to the conclusion that D. albomicans caught in Shanghai and areas nearby is from a few of places in the south of China-mainland. This conclusion agrees with the viewpoint that this species is on the speciation stage of migration towards north. We also discuss the mtDNA polymorphism within the species.

Animals↗
PubMed1994

Enhancement of expression of human granulocyte-macrophage colony stimulating factor by argU gene product in Escherichia coli.

Human granulocyte-macrophage colony stimulating factor (hGM-CSF) was cloned into expression vector pIN III-ompA1 and expressed in Escherichia coli JA221. When supplementation with a minor tRNA(AGA/AGG)Arg encoded by the E. coli argU gene, the expression level of hGM-CSF was raised about 3-4-fold, although there is only one rare AGG codon in hGM-CSF cDNA gene.

Base Sequence↗
PubMed1993

The influence of 5'-secondary structures upon ribosome binding to mRNA during translation in yeast.

The influence of 5'-secondary structure formation and 5'-leader length upon mRNA translation in yeast has been analyzed using a closely related set of cat mRNAs (Vega Laso, M. R., Zhu, D., Sagliocco, F. A., Brown, A. J. P., Tuite, M. F., and McCarthy, J. E. G. (1993) J. Biol. Chem. 268, 6453-6462). A cat mRNA with a relatively short unstructured 5'-leader (22 bases) had a ribosome loading about half that of a cat mRNA with an unstructured 5'-leader of 77 bases. The introduction of 5'-secondary structures at various positions throughout the 5'-leader of the cat mRNA inhibited translation initiation, the degree of inhibition being largely dependent upon the thermodynamic stability of the structure. Each mRNA carrying a 5'-secondary structure had a biphasic polysome distribution, indicating that the mRNA molecules were distributed between untranslated and well translated subpopulations. This suggests that once 5'-secondary structures are unwound, they reform slowly relative to the rate of translation initiation in yeast. Untranslated mRNA accumulated in 43 S preinitiation complexes, even when there were only 5 bases between the 5'-cap and the base of the hairpin. The data are consistent with the scanning hypothesis (Kozak, M. (1989) J. Cell. Biol. 108, 229-241) and suggest that 40 S ribosomal subunits bind to mRNA early in the scanning process, probably before mRNA unwinding has taken place.

Chloramphenicol O-Acetyltransferase↗