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Biomedical subjects

Z Feng

Publications and source records attributed to Z Feng.

At least 163 records · Page 9Linked to original sources
PubMed1998

Effect of artemether on hexokinase, glucose phosphate isomerase and phosphofructokinase of Schistosoma japonicum harbored in mice.

AIM: To study the effect of artemether (Art) on hexokinase (HK), glucose phosphate isomerase (GPI) and phosphofructokinase (PFK) of Schistosoma japonicum. METHODS: Mice infected with schistosome cercariae for 4-5 wk were treated ig with Art 100 or 300 mg.kg-1 and killed 24 h or 48 h after medication for collection of schistosomes. The activities of HK, GPI and PFK of the worms were determined by measuring the formation of NADPH or consumption of NADH. RESULTS: Worms from the infected mice treated ig with Art at a single dose of 300 mg.kg-1 the inhibition rates of HK activity of female and male worms were 33.7% and 13.7%, respectively 24 h after administration. Similar results were seen in GPI activity, but 48 h after medication, the inhibition rate of GPI increased to 46.2% (female) and 32.9% (male), respectively. Worms from mice treated with Art 100 or 300 mg.kg-1, the inhibitory effect on PFK in female worms was found much higher than that of male worms the inhibition rates of PFK were 64.9%-71.0% in female worms and 16.3%-54.2% in male worms, respectively at 24 h and 48 h after treatment. CONCLUSION: The results suggest that in the glycolytic pathway of schistosome PFK might be one of the targets attacked by Art.

Animals↗
PubMed1998

[Continuous cultivation of a large number of Plasmodium falciparum gametocytes in carbon dioxide incubator].

AIM: To establish a method for continuously cultivating a large number of P. falciparum gametocytes in vitro using carbon dioxide incubator. METHODS: The number of gametocytes produced in experimental and control groups was compared after the addition of various concentrations of NaHCO3 to the culture medium. RESULTS: The gametocytes began to rise on day 5 of cultivation and reached a peak on day 11-13. The peak gametocyte loads were 1.9% +/- 0.6% and 1.3% +/- 0.4% (P < 0.05) in experimental and control group, respectively, indicating that the complete medium with 30 mmol/L sodium bicarbonate was beneficial to gametogenesis. The numbers of stages I-V gametocytes rose to a peak on d5, d7, d11, d13 and d15, respectively. On day 15 the percentage of stage V gametocytes was 7.1%-52.6% with an average of 24.3%. The ratio of macrogametocyte to microgametocyte was 12.8:1. The parasites were able to produce high gametocytaemia up to 24th subculture after thawing. Laboratory reared Anopheles stephensi fed through membrane on blood infected with P. falciparum were dissected, no oocyst was found in the midgut. CONCLUSION: A culture system which could consistently and stably produce a large number of gametocytes of P. falciparum was established.

Animals↗
PubMed1998

[The construction of a general adeno-associated virus vector].

The general adeno-associated virus(AAV) vector pACR-Neo was constructed by substituting AAV's construct gene with cassette that was composed of CMV-IE promoter, multiple cloning sites and SV40-polyA. After transfecting pACR-Neo into recombinant AAV's packaging cell line AE1201, which was infected by Adenovirus 5 before transfection, we got rAAV/ACR-Neo at the titer of 4.2 x 10(5) CFU/ml. Using rAAV/ACR-Neo infected host cell A549, the recombinant AAV could transfer reporter gene Neo into host cell and mediate the integration of viral genome into host cell's chromosome DNA. By extracting chromosome DNA of host cell A549 that had been infected by rAAV/ACR-Neo, and digestion respectively with restriction endonuclease PvuII and HindIII, each of which has only one cutting site within rAAV/ACR-Neo's genome. We did Southern blot to check the hybridization of endonuclease digested chromosome to digoxin labelled Neo gene probe. After analyzing the experimental results, we found that rAAV/ACR-Neo's genome had integrate into host cell's chromosome compared to wild type AAV's site-specific integration. Through this work, we constructed a general AAV vector successfully. It lays foundation for research on AAV vector and application on gene therapy.

Adenoviridae↗
PubMed1998

[Adeno-associated virus vector mediated gene transfer of HSVI-TK and its effect on killing cancer cell].

The plasmid pACTK-19 was constructed by inserting HSVI-TK gene into the multiple cloning sites of the general adeno-associated virus(AAV) vector pACR-Neo. When plasmid pACTK-19 was transfected to recombinant AAV's packaging cell line AE1201, which was exposed to Adenovirus 5 for two hours before transfection, we got rAAV/ACTK at the titer of 3.4 x 10(5) CFU/ml. After infecting human lung cancer cell A549 with rAAV/ACTK, we extracted host cell's chromosome cDNA and amplified part of the HSVI-TK sequence by a pair of HSVI-TK's primers and then hybridized to digoxin labelled HSVI-TK gene probe. We got corresponding positive band and it proved the integration of HSVI-TK into host cell's chromosome cDNA. By reverse transcripting rAAV/ACR-Neo infected A549 total cell RNA, we amplified part of HSVI-TK sequence and hybridized to Neo gene probe. The corresponding positive band demonstrated the expression of HSVI-TK. So through rAAV/ACTK, HSVI-TK was transferred into host cells and was expressed in them, the rAAV's genome was integrated into host cell's chromosome DNA. Connecting with Ganciclovir (GCV), the HSVI-TK gene transfer mediated by rAAV/ACTK, could inhibit the synthesis of chromosome DNA and lead to the killing of the lung cancer cell. This work proved that recombinant AAV could be used as vector for gene transduction to cancer cell, and also laid foundation for further research and application of AAV vector.

Cloning, Molecular↗
PubMed1998

[Effect on HLA-I expression in the presence of antisense oligonucleotides complementary to hepatitis B virus x gene].

In order to investigate inhibition of HLA-I expression by antisense oligonucleotides in vitro, three pieces of antisense phosphorothioate oligonucleotides (ASODN) complementary to hepatitis B virus (HBV) x gene key regions namely, 1510-1530, 1555-1581, 1768-1791 were synthesized. We also synthesized a SOND (sense strand) with same sequence of 1510-1530 as control. The specificity of inhibitory effect of the ASOND was determined using 2215 cell line by detection of HBxAg. In addition, we observed the inhibitory effect of ASODN on human HLA-I utilizing 2215 cells, the cells were stained with monoclonal antibody against human HLA-I heavy chain molecules, with fluorescenated sheep antimouse antibody as the second antibody and then analyzed on a EPICS profile II flow cytometer. HLA-I mRNA were assayed by in situ hybridization with a HLA-I heavy chain cDNA probe. The results indicated these ASODN could inhibit the expression of HBxAg, as well as HLA-I in cell surface. The result of 1 in situ hybridization showed that the decreased cell surface expression was correlated with steadily decreasing state of mRNA levels. The mechanism of action may be due to the inhibition of HBxAg by sequence specific ASODN, then resulting in decreasing of its transactivating effect on the HLA-I promoter.

Gene Expression↗
PubMed1998

[HLA-Cw genotyping of serologically and non-serologically defined alleles using sequence-specific primers (PCR-SSP) in a Shanghai Han population].

The new classical complement-mediated microlymphocytotoxicity test can detect a total of 10 different serologically defined antigen specificities (CWl-10) encoded by HLA-Cw locus. However, the blank amounts to 20%-50% for there are Cw antigens which can not be detected with antisera available. We adopted a PCR-SSP method to genotype a sample of 70 subjects collected from a Chinese Han population in Shanghai. We identified for the first time the following non-serologically defined HLA-Cw alleles in the Chinese Han population: Cw*1201/1202,1203,1301,14,1601,1602,1701, and also the serologically defined HLA-Cw alleles such as: Cw*01,02,0302/0304,0303,04,0501,0602,0701/0702/0703,08. With this sample we have made a survey of HLA-Cw allele frequencies in a Chinese Han population in Shanghai, with blank frequency being lowered from 0.307 to 0.028. The Cw*08 was originally considered to be rare in Chinese population. However, we found 12 cases of Cw*08 in this sample, which clearly does not coincide with the original point of view. Our results confirmed that PCR-SSP typing is rapid and accurate for HLA-Cw alleles.

Alleles↗
PubMed1997

Associations of race/ethnicity, education, and dietary intervention with the validity and reliability of a food frequency questionnaire: the Women's Health Trial Feasibility Study in Minority Populations.

This report describes the associations of race/ethnicity and years of education with the validity, reliability, and bias of a self-administered food frequency questionnaire (FFQ) designed to be sensitive to low-fat, regional, and ethnic dietary patterns. Data were from the Women's Health Trial Feasibility Study in Minority Populations, a randomized clinical trial conducted between 1992 and 1994 to test the feasibility of a low-fat dietary intervention that targeted low-income, black, and Hispanic women. Of 1,015 participants eligible for these analyses, 28.1% were black, 16.2% were Hispanic, and 12.3% had not completed high school. The analyses focused on percentage of energy obtained from fat, and used 4-day food records as the criterion instrument. Validity at baseline, defined as the correlation between FFQs and food records, was lower among blacks than among whites (0.26 vs. 0.49; p < 0.001), did not differ between Hispanics and whites, and was lower among women with fewer years of education (0.19, 0.35, 0.49, and 0.42 for <12, 12, 13-15, and > or =16 years of education, respectively; for trend, p < 0.05). Six months after randomization, validity increased in most race/ethnicity and education subgroups, and differences across groups became small and statistically nonsignificant. Validity increased significantly among participants receiving the dietary intervention, while increases among control women were somewhat smaller. Reliability, defined as the correlation between baseline and 6-month measures among controls, was similar across racial/ethnic and educational groups. Bias at baseline, defined as the mean value from the FFQ minus the mean from the food record, was 4.6 percentage points of energy from fat; it was lowest among blacks (p < 0.01) and did not differ by years of education. These results suggest that special protocols which address participant training may be necessary when using self-administered FFQs in minority or poorly educated populations.

Aged↗
PubMed1997

Characterization of the long-lasting activator protein-1 complex induced by kainic acid treatment.

Kainic acid is known to induce seizures, neuronal damage and cell loss in the rat hippocampus. Our laboratory has shown that a single kainic acid injection elicits acute increases of activator protein-1 DNA-binding activity and this activity stays at an elevated level for 2 weeks after kainic acid injection. However, some pathological changes such as mossy fiber sprouting do not occur until 2-3 weeks after the kainic acid injection and the specific transcription factors regulating the long-term events after kainic acid treatment are not clear. To determine the involvement of activator protein-1 transcription factors in the long-term events after kainic acid treatment, gel mobility-shift and Western blot analyses were used. The results showed that two activator protein-1 complexes with different mobilities occur during the acute stage. However, only the faster-migrating complex as well as the 35-37-kDa fos-related antigen and Jun-D proteins were seen during the late stage. These results suggest that different activator protein-1 complexes exist at different stages after convulsions and that they regulate ensembles of different genes.

Animals↗
PubMed1997

A single dose of kainic acid elevates the levels of enkephalins and activator protein-1 transcription factors in the hippocampus for up to 1 year.

Neuronal plasticity plays a very important role in brain adaptations to environmental stimuli, disease, and aging processes. The kainic acid model of temporal lobe epilepsy was used to study the long-term anatomical and biochemical changes in the hippocampus after seizures. Using Northern blot analysis, immunocytochemistry, and Western blot analysis, we have found a long-term elevation of the proconvulsive opioid peptide, enkephalin, in the rat hippocampus. We have also demonstrated that an activator protein-1 transcription factor, the 35-kDa fos-related antigen, can be induced and elevated for at least 1 year after kainate treatment. This study demonstrated that a single systemic injection of kainate produces almost permanent increases in the enkephalin and an activator protein-1 transcription factor, the 35-kDa fos-related antigen, in the rat hippocampus, and it is likely that these two events are closely associated with the molecular mechanisms of induction of long-lasting enhanced seizure susceptibility in the kainate-induced seizure model. The long-term expression of the proenkephalin mRNA and its peptides in the kainate-treated rat hippocampus also suggests an important role in the recurrent seizures of temporal lobe epilepsy.

Animals↗
PubMed1997

Comparative study on the inhibitory effect of recombinant FN polypeptide CH50 and CH56 on the metastasis of melanoma cells.

On the basis of preparation of anti-metastatic recombinant FN polypeptides, CH50 and CH56, we further studied the function of these polypeptides. The capacity of CH50 binding with melanoma cells (ED50 30 mM) was higher than that of CH56 (ED50 45 mM). Both of the polypeptides could significantly suppress the binding of melanoma B16 cells to laminin. There was no significant difference in the inhibitory effect between two polypeptides. In the experimental metastasis of melanoma cells, both of CH50 and CH56 could significantly inhibit the metastasis of the tumor cells, and reduce the number of lung metastasis by about 80%. Our results suggest that III-11 and ED-A repeats influenced, to some extent, the binding capacity of bifunctional-domain polypeptide to cells, but did not affect the inhibition of the polypeptide on the metastasis of melanoma cells. The presence and connection of cell I and Hep II domains are the elements which determine the ability of recombinant FN polypeptides to inhibit the metastasis of tumor cells.

Animals↗
PubMed1997

Expression of foreign gene in mycobacterium regulated by human Mycobacterium tuberculosis heat shock protein 70 promoter.

The DNA fragments of 150bp length promoter of human Mycobacterium (M.) tuberculosis heat shock protein (hsp) 70 and 650bp length foreign gene, the Schistosoma japonicum glutathione S-transferase (Sj26GST) gene, were obtained by amplification with polymerase chain reaction. And the 150bp DNA sequence upstream initiation codon ATG of the human M. tuberculosis hsp 70 promoter that contains the sequence TTGAG and ATCATA which consensus with E. coli promoter's -35 and -10 region respectively, as well as ribosome binding site GGAGG at position -12--8 upstream the ATG were determined by SangerDideoxyribonucleotide-mediated chain-termination method. Then, the human M. tuberculosis hsp70 promoter and Sj26GST cDNA were cloned into E. coli-mycobacteria shuttle plasmid pBCG- 2000 to construct E. coli-Mycobacterium expression shuttle plasmid pBCG- Sj26 that can express Sj26GST gene. The M. smegmatis were electroporated and the positivecolonies were selected by kanamycin. The M. smegmatis containing the vector pBCG-Sj26 can be induced by heating and hydrogen peroxide (H2O2) to express GST. The molecular weight of the recombinant GST (rGST) was 26,000. The rGST contents that were about 10 percent of the total bacterial protein were analyzed by density scanning after running SDS-PAGE. This study would provide scientific evidences for application of hsp70 promoter in expressing foreign gene in mycobacterium and development of mycobacterium as multiple-valent vectoral vaccine.

Animals↗
PubMed1997

Competitive exclusion in a vector-host model for the dengue fever.

We study a system of differential equations that models the population dynamics of an SIR vector transmitted disease with two pathogen strains. This model arose from our study of the population dynamics of dengue fever. The dengue virus presents four serotypes each induces host immunity but only certain degree of cross-immunity to heterologous serotypes. Our model has been constructed to study both the epidemiological trends of the disease and conditions that permit coexistence in competing strains. Dengue is in the Americas an epidemic disease and our model reproduces this kind of dynamics. We consider two viral strains and temporary cross-immunity. Our analysis shows the existence of an unstable endemic state ('saddle' point) that produces a long transient behavior where both dengue serotypes cocirculate. Conditions for asymptotic stability of equilibria are discussed supported by numerical simulations. We argue that the existence of competitive exclusion in this system is product of the interplay between the host superinfection process and frequency-dependent (vector to host) contact rates.

Aedes↗
PubMed1997

To treat or not to treat: the case of tuberculosis.

Incomplete treatment of patients with infectious tuberculosis (TB) may not only lead to relapse but also to the development of antibiotic resistant TB-one of the most serious health problems facing society today. In this article, we formulate one-strain and two-strain TB models to determine possible mechanisms that may allow for the survival and spread of naturally resistant strains of TB as well as antibiotic-generated resistant strains of TB. Analysis of our models shows that non-antibiotic co-existence is possible but rare for naturally resistant strains while co-existence is almost the rule for strains that result from the lack of compliance with antibiotic treatment by TB infected individuals.

Antitubercular Agents↗
PubMed1997

One-shot delayed-type hypersensitivity reaction in the mouse liver causes a sustained liver injury to picryl chloride.

The developmental characteristics of liver injury induced by a delayed-type hypersensitivity (DTH) mechanism against picryl chloride were examined for 9 consecutive weeks in 3 mouse strains, BALB/c, Kunming and ICR mice. The changes of most biochemical parameters were similar in these three strains, namely, the activities of serum transaminases, lactic dehydrogenase, and prolidase were elevated significantly on day 1, during the first several weeks, and almost throughout the duration, respectively, of liver injury. The content of liver hydroxyproline was also increased after 1-9 weeks of liver injury. In addition, a significant decrease of liver weight, serum alkaline phosphatase and albumin level was observed in BALB/c and Kunming mice. Similar changes in liver histology were also found in the three strains. The hepatocellular necrosis and inflammatory infiltration into the portal area were the predominant features on day 1 and were still distinct during the subsequent several weeks. The mild or moderate hepatocellular degeneration, regeneration and connective tissue hyperplasia were observed after 1 or 3 weeks. A bridging necrosis between portal and portal was observed in several BALB/c and ICR mice, reflecting the possibility of exacerbation of liver injury. These results suggest that the liver injury could be caused and sustained by a one-shot DTH reaction to picryl chloride. The chronicity of the biochemical and histopathological characteristics may be helpful in elucidating the mechanisms of chronic development of liver injury.

Animals↗
PubMed1997

The ability of quantitative ultrasound to predict the mechanical properties of trabecular bone under different strain rates.

The ability of quantitative ultrasound to predict the mechanical properties of trabecular bone under different strain rates was investigated. Ultrasound velocity (UV) and broadband attenuation (BUA) were measured for 60 specimens of human trabecular bone. Samples were divided into two equal groups and loaded in compression at the strain rates of 0.0004 and 0.08 s-1. The ultimate strength, elastic modulus, and energy absorption capacity were determined for each specimen. Specimens tested at 0.08 s-1 had a mean value of strength 63% higher than the specimens tested at 0.0004 s-1. The elastic modulus and energy absorption capacity were 82% and 42% higher, respectively, for the higher strain rate. UV and BUA were significantly associated with most mechanical properties at both strain rates. All mechanical properties were also correlated strongly with a linear combination of UV and BUA for both the low and high loading rates. The use of ultrasound parameters may provide good clinical means for assessing the resistance of trabecular bone to both low and high energy trauma.

Aged↗
PubMed1997

Apoptosis in the rat mammary gland and ventral prostate: detection of cell death-associated genes using a coincident-expression cloning approach.

Apoptosis plays a striking role in the hormone-dependent involution of the mammary gland, but it has proved difficult to distinguish between the 'cell death' associated genes and the 'tissue remodelling' genes which are expressed concurrently. To identify cell death-associated genes, we have established a 'coincidence analysis' based on the previously described 'RNA differential display' method of Liang and Pardee (1992). Coincidence analysis allows the detection of genes expressed during related processes in different organs and was employed here to identify transcripts in which expression patterns are seen to be associated with apoptosis during involution of both rat mammary- and the ventral prostate glands. That the coincidence analysis is a promising approach can be seen from the fact that while widely accepted apoptosis markers such as transglutaminase (Fesus et al, 1987; Strange et al, 1992) and sulfated glycoprotein-2 (Buttyan et al, 1989; Strange et al, 1992; Guenette et al 1994) exhibited similar expression in both regressing tissues, transcription of tissue remodelling enzymes was minimal in the involuting prostate. We describe here the characteristics of five clones isolated which show coincident expression during programmed cell death in mammary and prostate tissues. Partial sequence analysis revealed for three clones high homologies with previously described genes; the putative rat homolog of the growth arrest gene gas-1 (Schneider et al, 1988; Del Sal et al, 1992), an homolog of the mouse 'Integrin Associated Protein' (IAP) (Brown et al, 1990; Lindberg et al, 1993) and the sequence encoding for the 'Allograft Inflammatory Factor' AIF-1 (Autieri et al, 1995; Utans et al, 1995). One clone displayed homology with an expressed human sequence tag and one clone unrelated to any known DNA sequence was isolated. The expression of these genes in involuting rat mammary and ventral prostate, was correlated with that in other organs and in situ hybridization was applied to establish that the secretory epithelial cells which undergo programmed cell death are the site of elevated expression during the course of involution. Furthermore, we conclude that the coincidence analysis approach described here could be easily applied to facilitate the characterization of gene expression i.e. for the detection and comparison of hormonally regulated genes in different organs.

Journal Article↗
PubMed1997

Long-term expression of Fos-related antigen and transient expression of delta FosB associated with seizures in the rat hippocampus and striatum.

Systemic administration of kainic acid (KA), an analogue of glutamic acid, causes limbic seizures and pathophysiological changes in adult rats that are very similar to human temporal lobe epilepsy. One of the earliest changes in gene expression after treatment with KA is the induction of immediate-early genes. The fos and jun families are frequently studied immediate-early genes that are induced by KA. Several groups, including ours, have recently reported that a 35-kDa Fos-related antigen (FRA) is induced for a protracted time by various stimuli. It has been suggested that this FRA is delta FosB, which has a molecular mass of approximately 35 kDa. The present study characterizes the long-term expression of FRA and delta FosB after systemic treatment with KA. Immunocytochemistry and western blot analysis using an antibody that cross-reacts with all known FRAs showed that a 35-kDa FRA was induced at high levels in both the hippocampus and striatum for up to 1 month by KA. A semiquantitative PCR analysis showed that delta FosB was induced by KA, but its expression lasted for only 6 h. This result was also verified by northern blot analysis. These results suggested that the 35-kDa FRA with long-term elevated levels seen with western blot analysis and immunocytochemistry is a new species of the FRA and not delta FosB. The long-term expression of FRA in both the hippocampus and striatum may be associated with the pathophysiological changes after KA administration.

Animals↗