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Biomedical subjects

R Wang

Publications and source records attributed to R Wang.

At least 487 records · Page 27Linked to original sources
PubMed1996

Protective efficacy against malaria of a combination sporozoite and erythrocytic stage vaccine.

Most malariologists believe that optimal malaria vaccines will induce protective immune responses against different stages of the parasite's life cycle. A multiple antigen peptide (MAP) vaccine based on the Plasmodium yoelii circumsporozoite protein (PyCSP) protects mice against sporozoite challenge by inducing antibodies that prevent sporozoites from invading hepatocytes. A purified recombinant protein vaccine based on the P. yoelii merozoite surface protein-1 (PyMSP-1) protects mice against challenge with infected erythrocytes, presumably by inducing antibodies against the erythrocytic stage of the parasite. We now report studies designed to determine if the PyMSP-1 vaccine protects against challenge with sporozoites, the stage encountered in the field, and if immunization with a combination of the PyCSP and PyMSP-1 vaccines provides additive or synergistic protection against sporozoite challenge. In two experiments, using TiterMax or Ribi R-700 as adjuvant, 3 of 19 mice immunized with the PyMSP-1 vaccine were completely protected against sporozoite challenge. The remaining mice had significantly delayed onset and lower levels of peak parasitemia than did control mice (11.1 +/- 2.8% vs. 36.7 +/- 1.6% in experiment #2, P < 0.01). Immunization with the combination vaccine reduced by approximately 50% the level of antibodies induced to PyCSP and PyMSP-1, as compared to that induced by the individual components. However, in two experiments, there was evidence of additive protection. Six of 19 (31.6%) immunized with the PyCSP vaccine, 3 of 19 (15.8%) immunized with the PyMSP-1 vaccine, and 10 of 19 (52.6%) immunized with the combination were completely protected against sporozoit challenge. This modest increase in protection in the combination group may be a reflection of additive anti-PyCSP and anti-PyMSP-1 immunity, since mice in the combination group had diminished levels of antibodies to each components. These studies indicate that considerable work may be required to optimize the construction, delivery, and assessment of multi-stage malaria vaccines.

Animals↗
PubMed1996

Familial Alzheimer's disease-linked presenilin 1 variants elevate Abeta1-42/1-40 ratio in vitro and in vivo.

Mutations in the presenilin 1 (PS1) and presenilin 2 genes cosegregate with the majority of early-onset familial Alzheimer's disease (FAD) pedigrees. We now document that the Abeta1-42(43)/Abeta1-40 ratio in the conditioned media of independent N2a cell lines expressing three FAD-linked PS1 variants is uniformly elevated relative to cells expressing similar levels of wild-type PS1. Similarly, the Abeta1-42(43)/Abeta1-40 ratio is elevated in the brains of young transgenic animals coexpressing a chimeric amyloid precursor protein (APP) and an FAD-linked PS1 variant compared with brains of transgenic mice expressing APP alone or transgenic mice coexpressing wild-type human PS1 and APP. These studies provide compelling support for the view that one mechanism by which these mutant PS1 cause AD is by increasing the extracellular concentration of Abeta peptides terminating at 42(43), species that foster Abeta deposition.

Alzheimer Disease↗
PubMed1996

DNA vaccines against malaria: immunogenicity and protection in a rodent model.

Since the first demonstration of the technology a few years ago, DNA vaccines have emerged as a promising method of vaccination. In a variety of experimental systems, DNA vaccines have been shown not only to induce potent immune responses, but also to offer many advantages in terms of ease of construction, testing, and production. In this article we summarize the progress achieved in development of DNA vaccines that can protect mice from infection by the rodent malaria parasite Plasmodium yoelii, describe initial studies of immunogenicity of a malaria DNA vaccine in a primate model, and outline the strategies being employed to design the next generation of malaria DNA vaccines.

Animals↗
PubMed1996

Human dermal fibroblasts produce nitric oxide and express both constitutive and inducible nitric oxide synthase isoforms.

Nitric oxide (NO) is produced by a variety of human and animal cells and is involved in a broad array of physiological and pathophysiological processes. It can cause vasodilation, serve as a neurotransmitter, and have anti-neoplastic, anti-microbial, and anti-proliferative effects. In this study, we have demonstrated that fibroblasts derived from human skin spontaneously produce NO and that this production can be enhanced by stimulating the cells with interferon-gamma and lipopolysaccharide. The production of NO by human dermal fibroblasts can be blocked by NG-monomethyl-L-arginine (L-NMMA). The inhibitory effect of L-NMMA on NO production was restored by addition of L-arginine but not D-arginine. By measuring the rate of conversion of [14C]L-arginine to [14C]L-citrulline, we show that unstimulated cells expressed only Ca2+-dependent NO synthase (NOS) activity (1.36 +/- 0.57 pmol/mg/min; n = 4) whereas stimulated cells expressed both Ca2+-dependent (2.60 +/- 0.54 pmol/mg/min; n = 4) and -independent (1.59 +/- 0.14 pmol/mg/min; n = 4) NOS activities. With reverse transcription polymerase chain reaction (RT-PCR), the 422-bp RT-PCR product for human endothelial constitutive NOS and the 462-bp RT-PCR product for human hepatocyte inducible NOS were detected in proportion to the amount of mRNA-related RT-cDNA added to the reaction mixture. Further evidence by immunocytochemistry demonstrated that human dermal fibroblasts express both constitutive and inducible NOS proteins. These data collectively suggest that in addition to macrophages and other inflammatory cells, nitric oxide production by dermal fibroblasts could be important during the inflammatory stages of wound healing and possibly also in the later stages of proliferation and tissue remodeling after skin injury in humans.

Animals↗
PubMed1996

Collagenase production is lower in post-burn hypertrophic scar fibroblasts than in normal fibroblasts and is reduced by insulin-like growth factor-1.

We recently demonstrated that the accumulation of extracellular matrix in post-burn hypertrophic scarring (HSc) tissues is, in part, caused by an overexpression of mRNA for fibronectin, type I, and type III procollagen. Here, we report that five different fibroblast cell strains derived from HSc tissues are deficient in collagenase activity relative to paired fibroblasts from normal skin of the same patients. Quantitative analysis demonstrated significantly lower (52.5 +/- 16.8% vs 100 +/- 8.3%; n = 9; p < 0.05) collagenase activity in conditioned medium from HSc fibroblasts relative to that obtained from the control. The expression of collagenase mRNA was also significantly depressed (51 +/- 7% vs 100 +/- 11%; n = 5; p < 0.05) in four of five strains of HSc fibroblasts examined. The level of mRNA for collagenase in both HSc and normal fibroblasts increased with serial passage, but at any given passage number, the expression of this transcript was lower in HSc fibroblasts. Insulin-like growth factor 1 (IGF-1), which is present at the site of HSc in high quantity, reduced collagenase mRNA but increased type I collagen mRNA expression in a time-dependent manner. The collagenase activity in conditioned medium derived from IGF-1-treated normal dermal fibroblasts was reduced (23.1 +/- 7.81% vs 100 +/- 6.6%; n = 7; p < 0.05). A significant reduction in collagenase mRNA and activity was also found in HSc fibroblasts following IGF-1 treatment. These findings suggest that IGF-1-induced suppression of collagenase mRNA and activity may be a mechanism by which IGF-1 promotes the development of post-burn HSc.

Adolescent↗
PubMed1996

Enhanced vasocontraction of rat tail arteries by toxoflavin.

1. It has been suggested that the toxic effect of toxoflavin (TXF) produced by Pseudomonas cocovenenas is mainly due to the impairment of electron transfer of the mitochondrial respiratory chain. However, the cardiovascular effect of TXF is unknown. In the present study, the effect of TXF on the isometric contraction of rat isolated tail artery strips and the underlying mechanisms were investigated. 2. The basal force of the tissues was not affected by the toxin. However, the application of TXF before or during KCl (60 mM) stimulation potentiated KCl-induced vasocontraction, specifically the tonic phase of the contraction. 3. When the vessel strips were precontracted with phenylephrine (Phe), TXF further enhanced the tonic contraction of the tissue. Pretreatment of tissues with TXF also potentiated subsequent vasocontraction induced by Phe. The vasocontractor effects of TXF and Phe, however, were not additive. 4. The vascular effect of TXF was not mediated by oxygen-derived free radicals since catalase and SOD did not affect TXF-enhanced vasocontraction. In contrast, the vasocontractor effect of TXF was dependent on extracellular Ca2+ and abolished by nifedipine (a Ca2+ antagonist). TXF also had no effect on caffeine- or U46619-induced vasocontraction. 5. It is suggested that TXF may potentially contract blood vessels via its effect on Ca2+ channels. This effect of TXF depends on the contractile status of the vascular tissues.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Effects of purinoceptor agonists on cytosolic Ca2+ concentration in swine tracheal smooth muscle cells in culture.

1. The effects of various purinoceptor agonists on intracellular Ca2+ concentration ([Ca2+]i) in swine tracheal smooth muscle cells in primary culture were examined to investigate the subtype of purinoceptors in these cells. 2. ATP (1 microM to 1 mM) concentration-dependently increased [Ca2+]i which was measured by monitoring the fluorescence signal of fura2. 3. alpha, beta-Me ATP at concentrations higher than 10 microM increased [ca2+]i in the presence of extracellular Ca2+. Responses to the drug were 12 +/- 5 and 61 +/- 4% of responses to ATP (100 microM) at 100 microM and 1 mM, respectively (n = 7). The response to 100 microM ATP was inhibited by 62% in the presence of 1 mM alpha, beta-Me ATP (n = 8), though the drug at concentrations lower than that did not affect the response to ATP. 4. ATP increased [Ca2+]i in the absence of extracellular Ca2+. The response to ATP in this condition was 40% of that in the presence of extracellular Ca2+ (n = 8). 5. Neither cibacron blue 3GA (10 microM) (n = 8) nor suramin (10 and 100 microM) (n = 10) affected the response to ATP (1 microM to 100 microM). 6. The rank order of potency in the absence of extracellular Ca2+ was UTP > ATP > adenosine 5'-o-(3-thiotriphosphate) > > ADP = alpha, beta-methylene adenosine 5'-triphosphate > 2-(methylthio)-adenosine 5'-(tetrahydrogen triphosphate). 7. UTP (1 microM to 100 microM) concentration-dependently increased inositol 1,4,5-triphosphate (IP3) production. 8. These results suggest that the increase in [Ca2+]i induced by purinoceptor agonists is mediated mainly via a nucleotide receptor in swine tracheal smooth muscle cells in primary culture.

Adenosine Triphosphate↗
PubMed1996

EGS4 dosimetry calculations for cylindrically symmetric brachytherapy sources.

Computer algorithms for electron binding correction to Compton scattering and for detailed simulation of K-edge characteristic x-ray production were incorporated into EGS4 unix version 2.0. Based on detailed modelling of the internal structures of sources, the modified version was used to calculate dose rate constants, radial dose functions, and anisotropy functions on the long axis for an 125I model 6711 source, 169Yb Type 5 and Type 8 sources, and a stainless steel clad (SS) 192Ir source. The geometry of these sources is cylindrically symmetric. Calculated results are generally in good agreement with corresponding values recommended by TG-43 and Monte Carlo results published by other authors. The influence of electron binding in Compton scattering on the calculated dose distribution for an 125I model 6711 source in water, and of different characteristic x-ray production models for 125I model 6711 and 192Ir SS sources, were also studied.

Brachytherapy↗
PubMed1996

Isolation of an ftsZ homolog from the archaebacterium Halobacterium salinarium: implications for the evolution of FtsZ and tubulin.

We have isolated a homolog of the cell division gene ftsZ from the extremely halophilic archaebacterium Halobacterium salinarium. The predicted protein of 39 kDa is divergent relative to eubacterial homologs, with 32% identity to Escherichia coli FtsZ. No other eubacterial cell division gene homologs were found adjacent to H. salinarium ftsZ. Expression of the ftsZ gene region in H. salinarium induced significant morphological changes leading to the loss of rod shape. Phylogenetic analysis demonstrated that the H. salinarium FtsZ protein is more related to tubulins than are the FtsZ proteins of eubacteria, supporting the hypothesis that FtsZ may have evolved into eukaryotic tubulin.

Amino Acid Sequence↗
PubMed1996

Erotomanic symptoms in 42 Chinese schizophrenic patients.

BACKGROUND: Reports on erotomania frequently include schizophrenic patients with secondary erotomania, but there are no reports on the prevalence and characteristics of erotomanic symptoms in schizophrenic patients. METHOD: A structured item on erotomanic delusions was added to the Chinese version of the Scale for Assessment of Positive Symptoms and administered to 448 randomly selected schizophrenic patients on admission to four psychiatric hospitals in China. RESULTS: Erotomanic symptoms were identified in 9.4% of the patients (42/448; 95% CI 6.9-12.4%) 4.5% (20/448; CI 2.8-6.8%) had erotomanic ideation and 4.9% (22/448; CI 3.1-7.4%) had fixed erotomanic delusions. Compared with patients without erotomanic symptoms, erotomanic patients were more likely to be male and unmarried, and they had a higher level of education, more severe grandiose delusions, more prominent hostility, and less severe negative symptoms. CONCLUSION: The relatively common occurence of erotomanic symptoms in Chinese schizophrenic patients may be related to the indirect manner of expressing sexual interest in Chinese culture and, thus, be an example of the cultural moulding of psychiatric symptoms.

Adolescent↗
PubMed1996

[Detection of placental alkaline phosphatase in ovarian cancer].

OBJECTIVE: To establish a method for diagnosis of malignant tumors by determination of the placental alkaline phosphatase (PLAP) in serum. METHODS: A solid phase enzyme immunoassay was adopated by an antibody against PLAP. PLAP in serum of 81 patients with malignant tumor and 86 healthy people as control were determined. RESULTS: In the control group, the PLAP activity showed deviative distribution, the 95th percentile values of PLAP in control group was 3.8U/L. If this value served as normal cut-off line, 18 cases among 81 patients with malignant tumors were positive. The positive rate was 22.2%, but the positive rates in ovarian cancer was 61.9%. CONCLUSIONS: The increasing of serum PLAP may be helpful for the diagnosis of malignant tumors especially ovarian cancer.

Alkaline Phosphatase↗
PubMed1996

Proliferation kinetics of chorionic villi in chromosomally normal and abnormal spontaneous abortions analyzed by premature chromosome condensation and northern blot.

The activity of cell proliferation in human chorionic villi (CV) obtained from early spontaneous abortions (SAB) and from elective abortions (EAB) was determined by means of premature chromosome condensation (PCC), and by Northern blot analysis of expression of proliferation antigens Ki67 and PCNA. The rate of chromosome aberrations among the SABs was 57%, while the EABs, taken as controls, were shown to be chromosomally normal. PCCs were induced by fusion of the chorionic interphase cells with mitotic Chinese hamster ovary (CHO) cells. To analyze the proliferation stages of the chorionic G1-interphases, the potential proliferation index (PPI) was ascertained. The PPI values found in SABs ranged from 36% to 97% as described for intensely proliferating tissues. They did not differ from the values found in the controls (34-90%), indicating maintenance of proliferation activity of CV cells even after death of the embryo in missed abortions. No significant PPI differences were observed between the abortion groups with different cytogenetic results. The expression of proliferation associated antigens Ki67 and PCNA showed no significant differences between mean values of the total of SABs and of the controls. However, the comparison of mean values of chromosomally abnormal with chromosomally normal SABs revealed a significantly reduced Ki67 activity in the SABs with chromosome aberrations. A similar results was obtained when comparing mean values of Ki67 and PCNA expression from trisomic SABs with those of the controls. By further subdivision of chromosome aberrations a decrease for the expression of both antigens in chorionic villi from early lethal trisomies, and a significantly increased Ki67- and PCNA-expression in triploidies became evident.

Abortion, Induced↗
PubMed1996

[Fingerprinting varieties of foxtail millet using probe gFM31].

Fifty-nine genotypes (landraces, varieties or breeder's lines) of foxtail millet (Setaria italica Beauv.) were used in DNA fingerprinting with a highly polymorphic probe, xPSF31. Fifty-eight types were distinguished, with only two genotypes giving identical band patterns. DNA sequencing of xPSF31 did not reveal any relationship with mini-or micro-satellite sequences. The probe revealed only weak signals in genomic DNA from other cereal species, wheat, barley, maize, rice, and pearl millet, indicating that xPSF31 is a Setaria genus specific sequence.

Base Sequence↗
PubMed1996

Observation on solubility and pro-nucleative activity of monoconjugated bilirubin.

OBJECTIVE: To explore the effect of monoconjugated bilirubin (MCB) on gallstone formation of both categories. METHODS: Using a newly established high performance liquid chromatography (HPLC) technique. MCB was extracted, prepared and purified from gallstone patients bile, and its solubility and pro-nucleative activity were observed. RESULTS: In a near physiological environment of biliary tract (pH 7.9 and temperature 37 degrees C), the aqueous solubility of MCB (558.25 +/- 5.96 microns) was only 1/7 of that of disconjugated bilirubin (DCB) (3410.9 +/- 2.42 microns), but 44 times higher than that of unconjugated bilirubin (UCB) (2.43 +/- 0.31 microns) (P < 0.01, between and two of them). Moreover, the solubility of MCB changed curvilineally with the alteration of pH, being highest at pH 7.9, zero at pH 4.5 and even lower than that of ionized UCB at pH above 9. In 3 groups of model bile systems made from Kibe's formula, the nucleation time (NT) was examined by polarized microscopy after 170 microns and 340 microns of MCB was added in group 1 and 2 respectively (group 3 was the control, with no MCB added). The NT was 3.33 +/- 0.52. 2.17 +/- 0.41 and 5.83 +/- 0.75 days respectively in the 3 groups (P < 0.05, between any 2 of the 3 groups) and the nucleative activity (NA) was 0.57 and 0.37 in group 1 and 2 respectively, which confirmed that MCB possessed a dose-related NA which was even stronger than that of glycoprotein (0.56) at the dose of 340 microns. CONCLUSIONS: MCB might play an essential role in the formation and nucleation of gallstones with its poor aqueous solubility and strong pro-nucleative activity via certain lithogenic mechanism.

Bile↗