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Biomedical subjects

Z Hao

Publications and source records attributed to Z Hao.

At least 37 records · Page 2Linked to original sources
PubMed1999

Differential expression of Hoxa-2 protein along the dorsal-ventral axis of the developing and adult mouse spinal cord.

We have used synthetic oligopeptides derived from the coding sequence of the murine Hoxa-2 protein to produce polyclonal antibodies that specifically recognize the Hoxa-2 recombinant protein. Immunohistochemical studies reveal a distinct pattern of spatial and temporal expression of Hoxa-2 protein within the mouse spinal cord which is concomitant with the cytoarchitectural changes occurring in the developing cord. Hoxa-2 protein is predominantly detected in the nuclei of cells in the ventral mantle region of 10-day-old mouse embryos. Islet-1, a marker for motor neurons was also shown to be co-localized with Hoxa-2 in nuclei of cells in this region. As development progresses from 10-days to 14-days of gestation, Hoxa-2 protein expression gradually extends to the dorsal regions of the mantle layer. The Hoxa-2 protein expression pattern changes at 16-days of embryonic development with strong expression visible throughout the dorsal mantle layer. In 18-day-old and adult mouse spinal cords, Hoxa-2 protein was expressed predominantly by cells of the dorsal horn and only by a few cells of the ventral horn. Double labeling studies with an antibody against glial fibrillary acidic protein (GFAP, an astrocyte-specific intermediate filament protein) showed that within the adult spinal cord, astrocytes rarely expressed the Hoxa-2 protein. However, Hoxa-2 and GFAP double-labeled astrocytes were found in the neopallial cultures, although not all astrocytes expressed Hoxa-2. Hoxa-2 expressing oligodendrocyte progenitor cells were also identified after double-labeling with O4 and Hoxa-2 antibodies; although cells in this lineage that have begun to develop a more extensive array of cytoplasmic processes were less likely to be Hoxa-2 positive. The early pattern of Hoxa-2 protein expression across transverse sections of the neural tube is temporally and spatially modified as each major class of neuron is generated. This congruence in the expression of the Hoxa-2 protein and the generation of neurons in the cord suggests that the Hoxa-2 protein may contribute to dorsal-ventral patterning and/or to the specification of neuronal phenotype. Dev Dyn 1999;216:201-217.

Age Factors↗
PubMed1999

PU.1 and Spi-B are required for normal B cell receptor-mediated signal transduction.

PU.1 and Spi-B have previously been implicated in the regulation of genes encoding B cell receptor (BCR) signaling components. Spi-B-/- B lymphocytes respond poorly to BCR stimulation; PU.1-/- mice, however, lack B cells, precluding an analysis of BCR responses. We now show that PU.1+/- Spi-B-/- B cells exhibit more extensive defects than Spi-B-/- B cells, indicating that both PU.1 and Spi-B are required for normal BCR signaling. Strikingly, BCR cross-linking results in substantially reduced protein tyrosine phosphorylation in mutant B cells. Further analysis shows that Igalpha is phosphorylated and syk is recruited and becomes phosphorylated but that BLNK and PLCgamma phosphorylation are defective in mutant cells. Our data support the existence of a novel component coupling syk to downstream targets.

Animals↗
PubMed1999

Characterization of cadmium uptake in Lactobacillus plantarum and isolation of cadmium and manganese uptake mutants.

Two different Cd(2+) uptake systems were identified in Lactobacillus plantarum. One is a high-affinity, high-velocity Mn(2+) uptake system which also takes up Cd(2+) and is induced by Mn(2+) starvation. The calculated K(m) and V(max) are 0.26 microM and 3.6 micromol g of dry cell(-1) min(-1), respectively. Unlike Mn(2+) uptake, which is facilitated by citrate and related tricarboxylic acids, Cd(2+) uptake is weakly inhibited by citrate. Cd(2+) and Mn(2+) are competitive inhibitors of each other, and the affinity of the system for Cd(2+) is higher than that for Mn(2+). The other Cd(2+) uptake system is expressed in Mn(2+)-sufficient cells, and no K(m) can be calculated for it because uptake is nonsaturable. Mn(2+) does not compete for transport through this system, nor does any other tested cation, i.e., Zn(2+), Cu(2+), Co(2+), Mg(2+), Ca(2+), Fe(2+), or Ni(2+). Both systems require energy, since uncouplers completely inhibit their activities. Two Mn(2+)-dependent L. plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment. They required more than 5,000 times as much Mn(2+) for growth as the parental strain. Mn(2+) starvation-induced Cd(2+) uptake in both mutants was less than 5% the wild-type rate. The low level of long-term Mn(2+) or Cd(2+) accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn(2+) and Cd(2+) uptake system.

Biological Transport↗
PubMed1999

Cloning, expression, and characterization of cadmium and manganese uptake genes from Lactobacillus plantarum.

An Mn(2+) and Cd(2+) uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd(2+) sensitivity as well as energy-dependent Cd(2+) uptake activity. Both transcription and translation of mntA were induced by Mn(2+) starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd(2+) uptake systems have been identified in L. plantarum: one is a high-affinity Mn(2+) and Cd(2+) uptake system that is expressed in Mn(2+)-starved cells, and the other is a nonsaturable Cd(2+) uptake system that is expressed in Cd(2+)-sufficient cells (Z. Hao, H. R. Reiske, and D. B. Wilson, Appl. Environ. Microbiol. 65:592-99, 1999). MntA was not detected in an Mn(2+)-dependent mutant of L. plantarum which had lost high-affinity Mn(2+) and Cd(2+) uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn(2+) and Cd(2+) transporter. On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases. The topology and potential Mn(2+)- and Cd(2+)-binding sites of MntA are discussed. A second clone containing a low-affinity Cd(2+) transport system was also isolated.

Amino Acid Sequence↗
PubMed1999

[Study on double antigens sandwich enzyme immunoassay for detection of Brucella specific antibodies in human and animals].

OBJECTIVE: In order to develop practicable methods for serodiagnosis, surveillance and epidemiological surveys in human and animals Brucellosis. METHODS: A double antigens sandwich Enzyme Immunoassay (DAgS-EIA include DAgS-ELISA and DAgS-DIEA) have been developed under the basis of first production conjugate of Brucella antigen with horseradish peroxidase. Serum samples from diagnosed patients, suspected patients of Brucellosis and sheep infected with Brucella in Henan and Hebei provinces as well as from experimental animals of infected with Brucella in laboratory detected through DAgS-EIA, I-ELISA, RBPT and SAT tests. RESULTS: Of the diagnosed and suspected Brucellosis patients, positive rates of DAgS-ELISA, RBPT, I-ELISA, DAgS-DIEA and SAT were 60.0%-62.9%, 48.6%-58.1%, 55.6%, 53.7% and 44.2% respectively; as for sheep with Brucella-infection, positive rate of the above mentioned 5 tests were 81.8%. CONCLUSION: Results showed that DAgS-EIA were not only specific and practicable but may use for Brucella specific antibodies detection in humans and various animals with only one conjugate of Brucella antigen with horseradish peroxidase.

Animals↗
PubMed1999

[Rat submandibular gland tumor induced by 3-methylcholanthrene].

OBJECTIVE: To study the genesis and the development of salivary gland tumor (SGT). METHODS: SGT animal models were established by injection of 3-methylcholanthrene (3-MCA) oil solution into 40 submandibular glands of Sprague-Dawley (SD) rats, then histopathology and ultrastructure of induced tumors were observed under microscope, and immunohistochemical detection of keratin and actin was carried out. RESULTS: 32 models of submandibular gland tumors were induced successfully, with 4 rats of squamous cell carcinoma and 28 leiomyosarcoma, and the carcinogenesis of 3-MCA and tissue genesis of induced tumors were discussed. CONCLUSION: Submandibular gland tumor can be induced by 3-MCA, and sarcoma was of high incidence.

Animals↗
PubMed1998

Carbocyclic analogues of the potent cytidine deaminase inhibitor 1-(beta-D-ribofuranosyl)-1,2-dihydropyrimidin-2-one (zebularine).

Three carbocylic analogues of the potent cytidine deaminase inhibitor (CDA) zebularine [1-(beta-D-ribofuranosyl)-1, 2-dihydropyrimidin-2-one, 1a] were synthesized. The selected pseudosugar templates correspond, respectively, to the cyclopentenyl moiety of neplanocin A (compound 4), the cyclopentyl moiety of aristeromycin (compound 5), and a newly designed, rigid bicyclo[3.1. 0]hexane moiety (compound 6). These three carba-nucleoside versions of zebularine were fashioned to overcome the inherent instability of the parent drug. Each target compound was approached differently using either convergent or linear approaches. The immediate precursor to the cyclopentenyl analogue 4 was obtained by a Mitsunobu coupling of pseudosugar 7 with 2-hydroxypyrimidine. The cyclopentyl analogue 5 was linearly constructed from carbocyclic amine 17, and the final target 6 was similarly constructed from the carbobicyclic amine 27. Of the three target compounds, only 5 showed a significant level of inhibition against human CDA, but it was 16 times less potent than zebularine (Ki = 38 microM vs Ki(apparent) = 2.3 microM). Although these carbocyclic analogues appeared to be more stable than zebularine, replacement of the electronegative CO4' oxygen for the less electronegative carbon in 4-6 presumably reduces the capacity of the pyrimidin-2(1H)-one ring to form a covalent hydrate, a step considered crucial for the compound to function as a transition-state inhibitor of the enzyme.

Animals↗
PubMed1998

[Determination of antioxidants BHT,BHA and PG in food with high performance liquid chromatography].

An accurate and rapid method for simultaneous determination of antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG) in food by reversed-phase high performance liquid chromatography was established. The sample was extracted with hexane. Being filtrated and dried by N2, the residues in evaporator was dissolved in a certain amount of water-C2H5OH (1:4, V/V) and filtered with 0.5 micron of filter membrane for HPLC analysis. The chromatographic conditions were Radial-PAK C12 column, methanol-water (92:8, V/V) mobile phase adjusted to pH = 3 with phosphoric acid and UV-280 nm detector. By using external standard method the analytical results showed that the coefficients of variation of PG,BHA and BHT were 0.61, 0.08 and 1.44 respectively, linear correlation coefficients were more than 0.999 and recoveries were 92%-98% (n = 6). The lowest detection limit was 0.5 mg/L.

Antioxidants↗
PubMed1998

[Diagnostic value of serum creatine kinase MB in patients with cardiac damage after electric injuries].

OBJECTIVE: To investigate the incidence of cardiac damage and the diagnostic value of serum myocardial enzyme following electric injuries. METHOD: 32 patients with electrical contact injuries were evaluated by serial electrocardiograms (ECG), creatine kinase (CK) and creatine kinase MB isoenzyme (CK-MB) determinations. The patients were divided into two groups according to the ECG. RESULT: 17 patients showed abnormal ECG (Group A), and 15 normal ECG (Group B). Positive correlations were noted between CK, CK-MB and the size of electric burns. The difference of serum CK-MB and 1.1% of total CK (CK-MB in skeletal muscle) was defined as CK-MB difference. CK, CK-MB, CK-MB/total CK ratio and the CK-MB difference were significantly higher in group A than in group B (all P < 0.05). The CK-MB difference of 88% (15/17) patients in group A was more than 25 U/L, whereas that was 6.7% (1/15) in group B (P < 0.01). Six patients with CK-MB difference greater than 100 U/L had obvious cardiac damage. CONCLUSION: Cardiac damage is a common complication of electric injuries. The cardiac damage could be estimated by serum CK-MB, particularly by the CK-MB difference. The CK-MB difference might be a useful indicator for evaluating the severity of the cardiac damage.

Adolescent↗
PubMed1998

[Three-dimensional volumetric display--a new application of frequency up-conversion].

This paper discusses the present research situation and the application prospect of 3-D volumetric display technology. The possible usability and science significance of frequency up-conversion in 3-D volumetric display field are also demonstrated systematically. In ZBLAN: Pr, Yb glasses, we primarily demonstrated and achieved a new application of frequency up-conversion three dimensional volumetric display, using the two-frequency up-conversion of the rare earth ions. The efficiency of luminescence of Pr was enhanced much by the energy transfer between Pr and Yb ions.

English Abstract↗
PubMed1997

Long-term erythropoietin expression in rodents and non-human primates following intramuscular injection of a replication-defective adenoviral vector.

Erythropoietin (Epo)-responsive anemia is a debilitating complication of chronic renal failure and human immunodeficiency virus (HIV) infection that effects more than 150,000 Americans. Patients with Epo-responsive anemias are currently treated with repeated injections of recombinant human Epo. In the studies described in this report, we have examined the safety and efficacy of using a single intramuscular (i.m.) injection of replication-defective adenoviral vectors (RDAd) encoding Epo for the treatment of Epo-responsive anemias in both mice and non-human primates. Our results demonstrate that there is a threshold dose of virus (2.5-8 x 10(7) pfu/gram of body weight) which is required to obtain long-term Epo expression and polycythemia in both species. A single i.m. injection of mice with 10(9) pfu of an RDAd encoding murine Epo (AdmEpo) resulted in elevations in hematocrits from control values of 49 +/- 0.9% to treated values of 81 +/- 3%, which were stable for more than 1 year. Similarly, a single i.m. injection of a monkey with 4 x 10(11) pfu of an RDAd-encoding simian Epo (AdsEpo) resulted in elevations of hematocrits from control levels of 40% to treated levels of > or =70%, which were stable for 84 days. Intramuscular injection of monkeys with AdsEpo appeared to be safe in that we did not detect abnormalities in chest X-rays, serum chemistries, hematologic, or clotting profiles (apart from elevated hematocrits) or organ histologies during the 84-day time course of the experiment. Taken together, these results suggest the feasibility of using i.m. injection of RDAd for the treatment of Epo-responsive anemias in humans.

Adenoviridae↗
PubMed1997

p53 mediated sensitization of squamous cell carcinoma of the head and neck to radiotherapy.

Radiation resistant squamous cell carcinoma of the head and neck cell line JSQ-3 carries a mutant form of tumor suppressor gene p53. Treatment of these cells with an adenoviral vector containing wild-type p53 (Av1p53) was able to inhibit their growth in vitro and in vivo while having no effect on normal cells. More significantly, introduction of wtp53 also reduced the radiation-resistance level of this cell line in vitro, in a viral dose-dependent manner. Furthermore, this radiosensitization also carried over to the in vivo situation where the response of JSQ-3 cell-induced mouse xenografts to radiotherapy was markedly enhanced after treatment with Av1p53. Complete, long-term regression of the tumors for up to 162 days was observed when a single dose of Av1p53 was administered in combination with ionizing radiation, demonstrating the effectiveness of this combination of gene therapy and conventional radiotherapy. This sensitization of tumors to radiation therapy by replacement of wtp53 could significantly decrease the rate of recurrence after radiation treatment. Since radiation is one of the most prevalent forms of adjunctive therapy for a variety of cancers, these results have great relevance in moving toward an improved cancer therapy.

Adenoviridae↗
PubMed1997

Evidence supporting a signal transduction pathway leading to the radiation-resistant phenotype in human tumor cells.

A signal transduction pathway, involving oncogenes and their normal counterparts the proto-oncogenes, analogous to that for cell growth and differentiation has been proposed to lead to the phenotype of cellular radioresistance (RR). In this report we provide evidence demonstrating the existence of such a pathway by using antisense oligonucleotides (ASO) to reverse the RR phenotype. Utilizing ASO directed against the raf-1 gene, a central component of this proposed pathway, we were able to reverse the RR phenotype of human tumor cell lines having elevated HER-2 expression or a mutant form of Ha-ras, two genes upstream of raf-1 in signal transduction. Additionally, anti-ras ASO were able to radiosensitize HER-2 overexpressing cells. These results, which verify the presence of a signaling pathway leading to cellular RR, also have possible clinical implications for the use of ASO as a means to sensitize radioresistant tumors to radiation therapy.

Breast↗
PubMed1997

Restoration of the G1 checkpoint and the apoptotic pathway mediated by wild-type p53 sensitizes squamous cell carcinoma of the head and neck to radiotherapy.

BACKGROUND: A significant number of squamous cell carcinomas of the head and neck (SCCHN) resist radiation treatment, the most common form of adjuvant therapy for this disease. The presence of a mutant form of the tumor suppressor gene p53 has been correlated with disruption of programmed cell death (apoptosis) and reduced cell cycle arrest, resulting in increased radiation resistance and survival. METHODS AND RESULTS: We introduced by means of an adenoviral vector a functional p53 gene into a radiation-resistant SCCHN cell line that harbors mutant p53. Replacement of wild-type p53 restored the G1 block and apoptosis in these cells in vitro. Moreover, introduction of wild-type p53 sensitized SCCHN-induced mouse xenografts to radiotherapy in vivo. CONCLUSION: The combination of p53 replacement gene therapy with conventional radiotherapy may treat SCCHN more effectively.

Animals↗
PubMed1997

A zinc finger protein required for stationary phase viability in fission yeast.

Yeast cells exit the cell cycle and enter a metabolically inert stationary phase when starved for nutrients essential for normal proliferation. We have cloned a novel gene named rsv1+ (required for stationary phase viability) that is essential for fission yeast cell viability in a stationary phase induced by glucose starvation. rsv1+ encodes a 47 kDa protein with two zinc finger motifs that are partially homologous with Aspergillus nidulans CreA, Saccharomyces cerevisiae Mig1 and mammalian EGR-1/NGFI-A. Cells deleted for rsv1+ are unable to survive glucose starvation. Transcription of rsv1+ is negatively regulated by the cAMP pathway and induced by glucose starvation. Cells with the constitutively activated cAMP pathway are known to lose viability when grown to confluence or when starved for glucose. These cells are poor in rsv1+ induction and their viability loss is largely suppressed by ectopic expression of rsv1+. Thus, poor induction of rsv1+ is at least partially responsible for the viability loss. Analysis also showed that cells need to receive starvation signals before entry into the stationary phase in order to maintain viability in a glucose-poor environment.

Amino Acid Sequence↗
PubMed1997

[Analysis of vitamin K1 in Cephalanoplos segetum (Bunge) Kitam by high performance liquid chromatography].

A modified method for the analysis of vitamin K1 in Cephalanoplos segetum (Bunge) Kitam, an edible wild herb, is proposed in this paper. The ground herb sample was extracted with CHCl3, followed by evaporation to dryness with nitrogen. The residue was dissolved with methanol, filtered through 0.5microm micropore membrane and then determined on a Novapak C18, 150mm x 3.9mm i.d., column with methanol/isopropanol (70:30) as mobile phase and UV-248nm as detector. Recovery was more than 95% with CV 1.23%. The method is simple and accurate without saponification, extraction and evaporation procedures as those used previously.

Asteraceae↗