Biomedical subjects

Z Mao

Publications and source records attributed to Z Mao.

At least 55 records · Page 3Linked to original sources

PubMed1998

Rice dwarf phytoreovirus segment S11 encodes a nucleic acid binding protein.

The function of rice dwarf virus segment 11 and the corresponding segments of other phytoreoviruses is not yet determined. The amino acid sequence of Pns11, encoded by segment 11, contains a putative zinc finger and five flanking basic regions at the C-terminus. The full-length Pns11 protein and three truncated derivatives, which lack the N-terminus, the zinc-finger or the C-terminal five basic regions were expressed in Escherichia coli and their nucleic acid binding properties were studied. Pns11 interacts with single- and double-stranded forms of DNA and RNA in a sequence-nonspecific manner. The truncated derivative which contains both the zinc-finger and the C-terminal basic regions has the same binding properties as the full-length Pns11. However, removal of either of these domains prevents binding activity. The binding activity of Pns11 was drastically reduced when the blots were treated with a high concentration of EDTA. Moreover, Pns11 extracted from infected rice also binds to single-stranded RNA. These data suggest that RDV Pns11 binding activity is structure-dependent and it may play an important role in virus replication and/or genome assortment.

Amino Acid Sequence↗

PubMed1998

Protection of leukemic cells by deoxycytidine: in vitro measures of protection against cytosine arabinoside.

Plasma deoxycytidine levels can be very high in leukemia patients. Such levels strongly protected leukemia cell lines against cytosine arabinoside (araC), fludarabine and 2-chlorodeoxyadenosine when using clonogenic survival as the endpoint. This endpoint is not easily used when studying protection in clinical leukemia cell samples. Therefore, we tested other ways to quantify protection based on biochemical measures of viability or drug metabolism. The estimates of the strength of protection based on rates of DNA synthesis, cellular araC uptake and incorporation of araC into DNA were much lower than the estimates using clonogenic survival. The MTT viability assay gave excellent estimates and appears promising for studying protection in primary leukemia cell samples.

Cell Survival↗

PubMed1998

Tuftelin--aspects of protein and gene structure.

The acidic enamel protein tuftelin has now been cDNA cloned, sequenced and characterized in a number of vertebrate species. Recently, the bovine tuftelin gene structure was elucidated. Cloning of the human tuftelin gene and partial sequencing of a number of exons have also been achieved. Immunologically, the protein has been shown to be conserved throughout 550 million years of vertebrate evolution. The gene has been localized to the long arm of the autosomal chromosome 1. The mapping of the human tuftelin gene to a well-defined cytogenetic region could be important in understanding the etiology of autosomally inherited amelogenesis imperfecta, the most common hereditary disease of enamel. The present paper reviews the primary structure, mRNA/cDNA structure, and gene structure of tuftelin. It describes its immunolocalization at the light microscope level and at the ultrastructural level in both the ameloblast cells and in the extracellular enamel matrix. The timing of tuftelin expression and its possible roles in enamel formation are discussed.

Ameloblasts↗

PubMed1998

Changes in methionine adenosyltransferase during liver regeneration in the rat.

Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes (MAT1A and MAT2A, respectively) that catalyze the formation of S-adenosylmethionine (SAM), the principal methyl donor. We previously showed that MAT2A expression was associated with more rapid cell growth. Here we examined changes in hepatic MAT gene expression and related consequences after two-thirds partial hepatectomy (PH) in rats. The mRNA levels of both MAT forms increased from 3 to 6 h, but the MAT1A level then fell below baseline from 12 to 24 h, whereas the MAT2A level remained elevated up to 4 days after PH. The increase in the MAT2A mRNA level was due to increased gene transcription and mRNA stabilization. The change in the MAT1A mRNA level was posttranscriptional and did not require de novo protein synthesis. Changes in MAT activity were consistent with an increased amount of MAT isozymes. SAM levels, the ratio of SAM to S-adenosylhomocysteine (SAH), and DNA methylation fell from 6 to 24 h, whereas SAH levels increased slightly at 12 and 24 h after PH. Both increased SAM utilization and MAT2A gene expression likely contributed to the fall in SAM.

Animals↗

PubMed1998

Tuftelin mRNA is expressed in a human ameloblastoma tumor.

RT-PCR, Southern blotting and DNA sequencing have established for the first time that tuftelin mRNA is expressed in human ameloblastoma tumor. The expression of amelogenin mRNA in ameloblastoma was also established, confirming earlier reports by Snead et al. These results corroborate, on a molecular level, the enamel organ epithelial origin of ameloblastoma. In view of the present results, it is interesting that previous studies have indicated that although ameloblastoma, a non-mineralized odontogenic tumor, transcribes amelogenin mRNA, amelogenin (and enamelin) proteins are not expressed in this tissue. However, in mineralizing odontogenic tumors, both these classes of proteins are expressed.

Ameloblastoma↗

PubMed1998

[Inhibition effects of tumor infiltrating lymphocytes from oral cancer on nude mice transplanted tumor established with human tongue carcinoma cell lines].

OBJECTIVE: To observe the in vivo inhibition effects on nude mice transplanted tumor with tumor infiltrating lymphocytes (TILs) isolated from primary mass of oral cancer. METHODS: Established the transplanted tumor model of human tongue cancer at the back of BALB/C nude mice with subcutaneous injection of squamous cell carcinoma lines Tca 8113. TILs isolated from patients with Oral cancer, combining with low dose of cyclophosphamide (Cy: 50 mg/kg), were locally injected into the peripheral site of tumor. The inhibition rate (IR) was calculated by the volume of tumor mass from the 1st to the 8th week, and the weights at the 8th week after tumor dissection. RESULTS: 1. Group TIL + rIL-2 and group TIL + rIL-2 + Cy both exerted a strong inhibition effect on the transplanted tumor within three weeks. The Inhibition rate (IR) were 86.1% +/- 0.4% and 97.7% +/- 0.6% respectively at the 3rd week, while 32.1% +/- 0.3% and 80.6% +/- 0.3% at the 8th week. 2. TIL + rIL-2 + Cy expressed a stronger effect and a longer inhibition time. The IR of TIL + rIL-2 and TIL + rIL-2 + Cy were 20.0% +/- 1.4% and 75.5% +/- 2.5% respeetively at the 8th week (P < 0.01). CONCLUSION: This study demonstrated that TILs from patients with oral carcer possess strong in vivo inhibition on nude mice transplanted tumor, and low dose of cyclophasophamide can enhance the inhibition effect and prolong the inhibition time.

Animals↗

PubMed1998

[Histologic study for effects of ox collagen in forming of new bone with quantitative method in animal models].

In this study, collagen was implanted into mandibular defects of 10 dogs. After operations, the samples were examined with microscope and quantitative method at 10 periods. Results showed that collagen did not affect bone growth and new bone grew into collagen directly. There was no fibrous capsule between collagen and new bone. Eventually, majority of collagen was resorbed and replaced by bone tissue. It was concluded that collagen has a good histocompatibility.

Animals↗

PubMed1998

[Cellular compatibility study of ox collagen with fibroblast cells].

The cell culture method was used to evaluate the cytotoxicity of ox collagen for clinical use. Direct method was chosen to examine the shape and growth of cells. Results showed that the cell shape was normal and the growth was well. The cytotoxicity of ox collagen conformed to the standards made by International Organization for Standardization (ISO). This study demonstrated that ox collagen doesn't restrain the growth of cells and has good biocompatibility.

Biocompatible Materials↗

PubMed1998

[Determination of Y, Ce, Ba and Cu in Y(1-x) Ce(x),Ba(2)Cu(3)O(y), using x-ray fluorescence fundamental parameter method].

The determination of Y, Ce, Ba and Cu in a series of Y(1-x)Ce(x)Ba(2)Cu(3)O(y) samples has been performed using X-ray fluorescence fundamental parameter method. The composition is given in atomic percentage. The results agree well with those obtained by ICP. It is shown that this method is appropriate for the determination of compositions of the high temperature superconductors. In addition, the influence of oxygen on analytical elements has been discussed in this paper. The fraction of the matrix total mass absorption that is associated with oxygen for each analytical line can not be larger than 3.44%. The determined composition of the samples show different from their nominal composition,which may affect the properties of high temperature superconductor.

English Abstract↗

PubMed1997

[A quantitative study of microvascular density and proliferating cell ratio in buccal mucosa squamous cell carcinoma].

By the ABC enzyme labelling method we studied the microvascular density and proliferating cell ratio in buccal mucosa squamous cell carcinoma (BMSCC) and in normal buccal tissues quantitatively. These two parameters in BMSCC are 208% and 335% (P < 0.05) respectively which are distinctly higher than those of the normal buccal tissues, indicating malignant features of the carcinoma. The distribution of proliferating cells, corresponds to the area where the microvascular density is high, mainly in the periphery and basal parts of cancer nests. There is a dependent relationship between them, showing a linear positive correlation statistically. The results confirm that angiogenesis and cancer cell proliferation promote each other. They are two important indexes of the local biological behavior of BMSCC and are very important to predict the malignant potential and to evaluate therapeutic effect for BMSCC.

Adult↗

PubMed1997

[Histopathologic and immunochemical changes in Sjögren's syndrome].

To research into the causes of sjögren's syndrome, we investigated the lacrimal gland tissues of 6 cases of sjogren's syndriome by using electronmicroscopy and immunochemical methods. The results revealed that at the early stage the lacrimal gland cells showed degeneration, irregular arrangement and many intracellular vacuoles. At the middle stage, some lymphocytes infliltrated into the gland tissues. And at the advanced stage, lymphocytes and collagenous fibers were there in substitution of gland cells.

Adult↗

PubMed1997

[Antitumor effect of TIL combined with radiotherapy on mouse uterocervical cancer U14].

After yielding culturing mouse TIL from U14 with Rosenberg's technique, the authors observed the antitumor effect of TIL combined with radiotherapy on established mouse transplanted tumor of uterocervical cancer U14. The results demonstrated TIL treatment or radiotherapy could inhibit the tumors growth. Combination showed a stronger inhibition and the E/O value was 1.1. It implied that an additive effect was gotten when combining TIL with radiotherapy.

Animals↗

PubMed1997

[Dynamic distribution in vivo of TIL from human tongue cancer after local injection in animal model].

On the basis of established nude mice transplanted tumor model of human tongue squamous cell carcinoma, peritumor injection was performed with 3H-TdR labeled TIL from human tongue cancer after 4 weeks culture. The dynamic distribution of 3H-TIL in vivo was learned through detecting the radioactivity of the target tissues. The results demonstrated that 3H-TIL was found in the whole body. There were about 2.1-30 times more in tumor tissues than in normal tissues and 3H-TILs even collected in the tumor tissues distal to the injective sites. The nearer to the injective sites the tumor tissues, the more 3H-TIL collected. It showed that local injection of TIL could be expected to exert a better antitumor effect.

Adult↗

PubMed1997

[Maxillofacial injury: clinical analysis of 284 cases].

Maxillofacial injury is common in war or in the routine life. Always accompanying trauma of other sites of the body, it has its own characters and leads to serious outcome. This article made a clinical analysis of 284 cases of maxillofacial injury from following aspects: onset of wounded, characters and chief complications of maxillofacial soft and hard tissues injury and foreign bodies left in place. The authors also discussed their experiences at emergency management.

Accidents, Traffic↗

PubMed1997

[Determination of Cu, Pb, Sn, Fe and Zn in the ancient Chinese bronzes by X-ray fluorescence filter paper method].

The determination of Cu, Pb, Sn, Fe and Zn in the ancient chinese bronzes has been performed using X-ray fluorescence filter paper method. The result is satisfactory. The samples are dissolved in the HCl-H2O2 system, ard then the solution is dropped on the filter paper. It is convenient for detection by XRF. In addition this method is efficient to reduce the matrix effect of sample. The correlative coefficients of calibration curves between element concentration and X-ray intensity are over 0.99. The rate of recovery is 97-104%, and the relative standard deviation for each element is less than 2.00%. The copper's result measured by this method agrees well with that of chemical method. This method is simple, rapid and accurate. It is also applied to determine the elements in the other ancient objects.

English Abstract↗

PubMed1997

Induction of c-fos/c-myc expression by epidermal growth factor decreases with alteration of their gene binding proteins in senescent fibroblasts.

OBJECTIVE: To observe the changes of proto-oncogene c-fos/c-myc expression and its relation to specific transcription factors in human senescent fibroblast after epidermal growth factor (EGF) addition. METHODS: The c-fos/c-myc expression were analysed by Northern blot. Transcription factors were analysed by Southwestern blot. RESULTS: (1) The expression of c-fos/c-myc was less susceptible to induction by EGF as the cells aged. (2) EGF increased the binding of protein P91 to c-fos with regulatory sequence and P80 to c-myc with regulatory sequence, but the increased levels of both proteins were significantly reduced in senescent cells. CONCLUSIONS: Inability of c-fos/c-myc gene induction by EGF in senescent cells might be correlated with some DNA-binding proteins.

Cellular Senescence↗

PubMed1996

Design and synthesis of histidine analogues of folic acid and methotrexate as potential folylpolyglutamate synthetase inhibitors.

Folypolyglutamate synthetase (FPGS) is responsible for the conversion of naturally occurring folates and antifolates to their poly-gama-glutamyl derivatives, which are the forms required for intracellular retention of folates and are also the preferred substrates (cofactors) for most folate-dependent enzymes. Folate and methotrexate analogues 6 and 4, with L-histidine in place of L-glutamate, were designed and synthesized as potential FPGS inhibitors. Target compound 5, the N tau-(carboxymethyl)-L-histidine derivative of 4, was also prepared. Compounds 4 and 5 inhibited the growth of L1210 cells (IC50 values: 0.091 and 0.15 microM, respectively) and were potent inhibitors of L1210 dihydrofolate reductase. No significant inhibition of FPGS by 4, 5, or 6 was observed at the high pH of the standard enzyme assay. This could be the consequence of a lack of protonation of the basic side chains, which is likely to be required for FPGS inhibitory activity. The observed cytotoxicity indicates that partial protonation of the imidazole ring permits cellular uptake of the analogues.

Animals↗

PubMed1996

Functional and physical interactions between mammalian achaete-scute homolog 1 and myocyte enhancer factor 2A.

The mammalian achaete-scute homolog 1 (MASH1) protein is required for the early development of the nervous system. However, the molecular and biochemical mechanism by which MASH1 acts to determine neurogenesis are still unknown. The myocyte enhancer factor 2A (MEF2A) is a MADS transcription factor that is essential for the specification and differentiation of the muscle lineage. Here we show that MEF2A and MASH1 are coordinately induced during the differentiation of the teratocarcinoma cell line P19 along a neuronal lineage and that in transient transfection assays, MEF2A and MASH1 cooperatively activate gene expression. This cooperativity appears to be due to a specific physical interaction between MEF2A and MASH1. Taken together, these findings suggest that MASH1 via a cooperative interaction with MEF2A may regulate the expression of specific genes that are critical for neuronal differentiation.

Animals↗