Biomedical subjects

C Luo

Publications and source records attributed to C Luo.

At least 73 records · Page 4Linked to original sources

PubMed2000

[Report on epidemic hemorrhagic fever (EHF) surveillance in 1999].

OBJECTIVE: To understand the epidemic tread of epidemic hemorrhagic fever (EHF) in 1999 and to develop programs for its control and prevention. METHODS: Epidemiological, zoo-epidemiologic, serologic and viral diagnostics were used to analyse the information of monthly and annual reports from surveillance spots. RESULTS: Twelve thousand nine hundred and thirty cases of EHF in all surveillance spots were reported with 135 cases of death in 1999. The morbidity and mortality were 5.37/100,000, and 1.04% respectively, which had a 1.47% decrease and 9.47% increase, comparing to that of 1998. The accordance of serological and clinical diagnosis was 67.25%, with rate of misreporting 1.28%. In animal surveillance, the density of mouse was 7.46% with predominant species Apodemus agrarius. In residential areas, the density of mouse was 6.21%, with predominant species Rattus norvegicus. For Apodemus agrarius in fields and Rattus norvegicus in residential areas, the indexes of HV carrier were 0.032 and 0.031 respectively in 1999. In spring and autumn, the indexes of HV carrier in Rattus norvegicus were apparently higher than that of Apodemus agrarius as the indexes of HV carrier in Rattus norvegicus were 0.028 and 0.036 comparing with 0.026 and 0.020 in Apodemus agrarius. CONCLUSION: It is suggested that more attention should be paid to the surveillance in low and medium-sized epidemic areas because northern China is dry with short rainy season while the epidemic situation in the serious epidemic areas had been under control to some degree.

Animals↗

PubMed2000

[The lymphocyte subset and blood interleukin-2 level in children with Henoch-Schönlein purpura before and after cimetidine treatment].

The objective of this study was to evaluate the effect of cimetidine treatment on cellular immunity in children with Henoch-Schönlein purpura. T cell subset was detected by double marker flow cytometry and the level of IL-2 in peripheral blood was measured by MTT method, before and after cimetidine treatment. The results showed that CD3+, CD4+ T cell subset, CD4+/CD8+ ratio, and blood IL-2 level increased after the treatment (P < 0.05). There was no significant change in CD8+ T subset after the treatment. These findings indicate that cimetidine can promote T lymphocyte proliferation and differentiation, especially TH1 lymphocyte activity.

Adjuvants, Immunologic↗

PubMed1999

Crystal structure of an inhibitor complex of the 3C proteinase from hepatitis A virus (HAV) and implications for the polyprotein processing in HAV.

The proteolytic processing of the viral polyprotein is an essential step during the life cycle of hepatitis A virus (HAV), as it is in all positive-sense, single-stranded RNA viruses of animals. In HAV the 3C proteinase is the only proteolytic activity involved in the polyprotein processing. The specific recognition of the cleavage sites by the 3C proteinase depends on the amino acid sequence of the cleavage site. The structure of the complex of the HAV 3C proteinase and a dipeptide inhibitor has been determined by X-ray crystallography. The double-mutant of HAV 3C (C24S, F82A) was inhibited with the specific inhibitor iodoacetyl-valyl-phenylalanyl-amide. The resulting complex had an acetyl-Val-Phe-amide group covalently attached to the S(gamma) atom of the nucleophilic Cys 172 of the enzyme. Crystals of the complex of HAV 3C (C24S, F82A) acetyl-Val-Phe-amide were found to be monoclinic, space group P2(1), having 4 molecules in the asymmetric unit and diffracting to 1.9-A resolution. The final refined structure consists of 4 molecules of HAV 3C (C24S,F82A) acetyl-Val-Phe-amide, 1 molecule of DMSO, 1 molecule of glycerol, and 514 water molecules. There are considerable conformational differences among the four molecules in the asymmetric unit. The final R-factor is 20.4% for all observed reflections between 15.0- and 1.9-A resolution and the corresponding R(free) is 29.8%. The dipeptide inhibitor is bound to the S(1)(') and S(2)(') specificity subsites of the proteinase. The crystal structure reveals that the HAV 3C proteinase possesses a well-defined S(2)(') specificity pocket and suggests that the P(2)(') residue could be an important determinant for the selection of the primary cleavage site during the polyprotein processing in HAV.

3C Viral Proteases↗

PubMed1999

Case study of the effects of atmospheric aerosols and regional haze on agriculture: an opportunity to enhance crop yields in China through emission controls?

The effect of atmospheric aerosols and regional haze from air pollution on the yields of rice and winter wheat grown in China is assessed. The assessment is based on estimates of aerosol optical depths over China, the effect of these optical depths on the solar irradiance reaching the earth's surface, and the response of rice and winter wheat grown in Nanjing to the change in solar irradiance. Two sets of aerosol optical depths are presented: one based on a coupled, regional climate/air quality model simulation and the other inferred from solar radiation measurements made over a 12-year period at meteorological stations in China. The model-estimated optical depths are significantly smaller than those derived from observations, perhaps because of errors in one or both sets of optical depths or because the data from the meteorological stations has been affected by local pollution. Radiative transfer calculations using the smaller, model-estimated aerosol optical depths indicate that the so-called "direct effect" of regional haze results in an approximately 5-30% reduction in the solar irradiance reaching some of China's most productive agricultural regions. Crop-response model simulations suggest an approximately 1:1 relationship between a percentage increase (decrease) in total surface solar irradiance and a percentage increase (decrease) in the yields of rice and wheat. Collectively, these calculations suggest that regional haze in China is currently depressing optimal yields of approximately 70% of the crops grown in China by at least 5-30%. Reducing the severity of regional haze in China through air pollution control could potentially result in a significant increase in crop yields and help the nation meet its growing food demands in the coming decades.

Agriculture↗

PubMed1999

Involvement of peripheral NMDA and non-NMDA receptors in development of persistent firing of spinal wide-dynamic-range neurons induced by subcutaneous bee venom injection in the cat.

To study the roles of peripheral excitatory amino acids receptor subtypes N-methyl-D-aspartate (NMDA) and non-NMDA receptors in persistent nociception, extracellular single unit recording technique was used to assess the effects of a single dose NMDA and non-NMDA receptor antagonists, AP(5) (5-aminophosphonovaleric acid) and CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) or DNQX (6,7-dinitroquinoxaline-2,3-dione), on s.c. bee venom-induced increase in firing of wide-dynamic-range (WDR) neurons in the spinal dorsal horn of the urethane-chloralose anesthetized cats. Subcutaneous bee venom injection into the cutaneous receptive field resulted in a single phase of increased firing of WDR neurons over the background activity for more than 1 h. Local pre-administration of AP(5) (200 microg/100 microl) or CNQX (8.3 microg/100 microl) into the bee venom injection site produced 94% (1.01+/-0.96 spikes/s, n=5) or 76% (2.97+/-0.58 spikes/s, n=4) suppression of the increased neuronal firing when compared with local saline (16.32+/-4.55 spikes/s, n=10) or dimethyl sulfoxide (DMSO) (12.37+/-6.36 spikes/s, n=4) pre-treated group, respectively. Local post-administration of the same dose of AP(5) produced a similar result to the pre-treatment group with a 67% inhibition of the mean firing rate, however, the same treatment with CNQX and even a higher dose of DNQX (100 microg/100 microl) did not produce any inhibition of the neuronal firing induced by s.c. bee venom injection (DNQX vs. DMSO: 23.91+/-0. 25 vs. 22.14+/-0.04 spikes/s, P=0.0298, n=5). In the control experiments, local pre-administration of the same dose of AP(5) or CNQX into a region on the contralateral hindpaw symmetrical to the bee venom injection site produced no significant influence on the increased firing of the WDR neurons [contralateral AP(5) vs. saline: 14.17+/-6.27 spikes/s (n=5) vs. 16.32+/-4.55 spikes/s (n=10), P0.05; contralateral CNQX vs. DMSO: 12.85+/-6.38 spikes/s (n=4) vs. 12. 37+/-6.36 spikes/s (n=4), P0.05], implicating that the suppressive action of local AP(5) or CNQX was not the result of systemic effects. The present results suggest that activation of the peripheral NMDA receptors is involved in both induction and maintenance, while activation of non-NMDA receptors is only involved in induction, but not in the maintenance of persistent firing of the dorsal horn WDR neurons induced by s.c. bee venom injection.

2-Amino-5-phosphonovalerate↗

PubMed1999

Phosphoryl oxime inhibition of acetylcholinesterase during oxime reactivation is prevented by edrophonium.

Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) is a key objective in the treatment of OP poisoning. This study with native, wild-type, and mutant recombinant DNA-expressed AChEs, each inhibited by representative OP compounds, establishes a relationship between edrophonium acceleration of oxime-induced reactivation of OP-AChE conjugates and phosphoryl oxime inhibition of the reactivated enzyme that occurs during reactivation by pyridinium oximes LüH6 and TMB4. No such recurring inhibition could be observed with HI-6 as the reactivator due to the extreme lability of the phosphoryl oximes formed by this oxime. Phosphoryl oximes formed during reactivation of the ethoxy methylphosphonyl-AChE conjugate by LüH6 and TMB4 were isolated for the first time and their structures confirmed by (31)P NMR. However, phosphoryl oximes formed during the reactivation of the diethylphosphoryl-AChE conjugate were not sufficiently stable to be detected by (31)P NMR. The purified ethoxy methylphosphonyl oximes formed during the reactivation of ethoxy methylphosphonyl-AChE conjugate with LüH6 and TMB4 are 10- to 22-fold more potent than MEPQ as inhibitors of AChE and stable for several hours at pH 7.2 in HEPES buffer. Reactivation of both ethoxy methylphosphonyl- and diethylphosphoryl-AChE by these two oximes was accelerated in the presence of rabbit serum paraoxonase, suggesting that organophosphorus hydrolase can hydrolyze phosphoryl oxime formed during the reactivation. Our results emphasize that certain oximes, such as LüH6 and TMB4, if used in the treatment of OP pesticide poisoning may cause prolonged inhibition of AChE due to formation of phosphoryl oximes.

Acetylcholinesterase↗

PubMed1999

Role of edrophonium in prevention of the re-inhibition of acetylcholinesterase by phosphorylated oxime.

We examined the role of edrophonium in the acceleration phenomenon using mouse wild-type and mutant D74N AChE inhibited with 7-(O,O-diethyl-phosphinyloxy)-1-methylquinolinium methylsulfate (DEPQ). With DEPQ-inhibited wild-type mouse acetylcholinesterase (AChE), the reactivation kinetic profile demonstrated one-phase exponential association only when 2-[hydroxyimino methyl]-1-methylpyridinium chloride (2-PAM) and 1-(2-hydroxy-iminomethyl-1-pyridinium)-1-(4-carboxy-aminopyridi nium)-dimethyl ether hydrochloride (HI-6) were used as reactivators. When 1,1[oxybis-methylene)bis[4-(hydroxyimino)methyl] pyridinium dichloride (LüH6) and 1,1-trimethylene bis(4-hydroxyimino methyl) pyridinium dichloride (TMB4) were used, the reactivation kinetic profile was biphasic in nature. Edrophonium had no effect on reactivation by 2-PAM and HI-6, but significantly accelerated LüH6- and TMB4-induced reactivation of DEPQ-inhibited wild-type mouse AChE. Comparison of the initial and overall reactivation rate constants with five oximes indicated that acceleration by edrophonium may be due to the prevention of re-inhibition of the reactivated enzyme by the phosphorylated oxime (POX) produced during the reactivation. With LüH6 and TMB4, about 2.5-fold increase in the reactivation rate constants was observed in the presence of edrophonium, but little or no effect was observed with the other three oximes. The initial reactivation rate constants were 5.4- and 4.2-fold of the overall rate constants with LüH6 and TMB4 as reactivators respectively, however, very little change was found between the initial and overall rate constants with the other three oximes. In experiments with D74N AChE, for which the inhibition potency of charged organophosphate (OP) was two to three orders less than wild-type enzyme, edrophonium had no effect on the reactivation by LüH6 and TMB4 and the time courses of reactivation were monophasic. The data from mutant enzyme substantiate the involvement of edrophonium in protecting POX re-inhibition of reactivated enzyme formed during the reactivation of OP-inhibited AChE.

Animals↗

PubMed1999

Lineshifts in the Fundamental Band of CO: Confirmation of Experimental Results for N(2) and Comparison with Theory.

We have used a three-channel version of a tunable difference frequency laser spectrometer to measure the collisionally induced lineshifts at room temperature for 26 lines of the fundamental band of CO perturbed by nitrogen. Each lineshift was obtained directly by comparing the line center positions of two simultaneous recordings, one for a pressure-shifted line, and the other for the same line in pure CO line at very low pressure. The experimental results are found to be in complete agreement with earlier measurements and confirm that shifts as small as 3 MHz may be measured in such a system. Our results are compared with theoretical calculations. The part of the shifting coefficient antisymmetric with respect to a change in sign of the line number m, is in disagreement with the calculations. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Line Broadening and the Temperature Exponent of the Fundamental Band in CO-N(2) Mixtures.

We have measured the width, Gamma, of many P and R lines of the fundamental vibration-rotation band of CO perturbed by N(2) at 348 K and pressures of about 50 kPa. We have also extended the measurements made earlier at room temperature. The broadening coefficients, gamma = Gamma/pressure, were obtained with an accuracy of 0.3% by fitting with a Lorentzian, a Voigt, and an empirical lineshape model that blends together a hard-collision model and a speed-dependent Lorentzian profile. In all cases the results are represented by an empirical exponential power law polynomial in the line number, m. Combining the data at the two temperatures yields the exponent n in the scaling law gamma(T(1))/gamma(T(2)) = (T(1)/T(2))(-n), as a function of line number. The broadening coefficients and the variation of the temperature exponent line number are compared with theory. In addition, the line-mixing parameters are also reported at 348 and 301 K. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Evolutionary pattern of influenza B viruses based on the HA and NS genes during 1940 to 1999: origin of the NS genes after 1997.

Phylogenetic analysis was carried out for genes encoding hemagglutinin (HA) (24 new and 25 previously reported sequences) and nonstructural proteins (NS) (22 new and 14 previously reported sequences) of influenza B virus isolates obtained from 1940 to 1999. Two antigenically and genetically distinct HA lineages are presently known to exist. Divergence into these two lineages was estimated to have occurred around 1969. Phylogenetic analysis of NS genes revealed that their phylogenetic relationships were not linked to the two HA lineages but suggested that reassortment of viral genes between the viruses of two HA lineages had occurred. In addition two distinct NS lineages which were not linked to the two HA lineages were observed. Viruses isolated after 1997 formed their own lineage in combination with B/Houston/84 while other virus isolates obtained from 1973 to 1995 comprised the other NS lineage.

Base Sequence↗

PubMed1999

Expression of barley ADP-glucose pyrophosphorylase in Escherichia coli: processing and regulatory considerations.

Full length cDNAs for barley ADP-glucose pyrophosphorylase (AGPase) coding for the large subunits of the endosperm and leaf homologues of the enzyme (AGPase-S1 and -S2, respectively) and for the small subunit protein from endosperm (AGPase-B1), have been expressed in Escherichia coli. The cDNAs for AGPase-S1 and -S2 required different induction conditions for their maximal expression and they encoded immunologically distinct proteins. The AGPase-S1 that was produced by E. coli had the same M(r) (58 kDa) as the corresponding protein in barley crude endosperm extracts, whereas the bacteria-produced AGPase-S2 (55 kDa) was larger than its counterpart from barley leaf preparations (53 kDa). An enzymatically active AGPase expressed in E. coli from a double construct containing cDNAs for AGPase-S1 and -B1 subunits was insensitive to the activation by 3-phosphoglycerate and to inhibition by inorganic phosphate, similarly to the enzyme in barley endosperm. Neither AGPase-S1 nor -B1 were active when expressed alone in the bacteria. The data are discussed with respect to possible mechanisms of intracellular targeting of immature AGPase-S proteins in barley tissues and regarding previous data on effector regulation of the barley enzyme.

Base Sequence↗

PubMed1999

Comparison between the comet assay and the oxygen microelectrode for measurement of tumor hypoxia.

BACKGROUND AND PURPOSE: Hypoxic cells are present in some solid tumours and are known to limit radiocurability. To compare two measures of tumour hypoxia, 25 patients with locally advanced disease and accessible tumours or metastatic nodes were examined using an oxygen microelectrode and the alkaline comet assay. MEASUREMENTS AND METHODS: For the comet assay, fine needle aspirate biopsies were taken immediately following a dose of 5-10 Gy. Single cells were examined for radiation-induced DNA strand breaks, and the percentage of radio-resistant hypoxic cells within the population was calculated from DNA damage histograms. For oxygen tension (pO2) measurements, multiple tracks were made using an Eppendorf oxygen microelectrode. The possibility that application of the first method might influence hypoxic fraction measurement by the second method was examined in a more controlled system by creating four tracks in murine SCC-VII tumours using an oxygen electrode, and measuring hypoxic fraction at subsequent times. RESULTS: For 28 tumours from 25 patients, hypoxic fraction measured by comet assay correlated with the percentage of PO2 values < 5 mmHg (r2 = 0.46, P < 0.001). The mean comet hypoxic fraction was 0.36 for five tumours with a median PO2 < 10 mmHg. For the remaining 23 tumours with a median PO2 > 10 mmHg, the mean hypoxic fraction was 0.09. Advancement of an oxygen electrode through SCCVII tumours had no significant effect on hypoxic fraction measured 5 min to 24 h later using the alkaline comet assay. CONCLUSIONS: Tumours defined as hypoxic based on a median pO2 < 10 mmHg appear to contain more than 20% radio-biologically hypoxic cells as estimated by the comet assay. In an animal tumour model, puncture of the tumour with an oxygen electrode did not influence hypoxic fraction measured using the comet assay, in agreement with the clinical data that the order in which the two methods were performed was not important.

Animals↗

PubMed1999

Primary hyperalgesia to mechanical and heat stimuli following subcutaneous bee venom injection into the plantar surface of hindpaw in the conscious rat: a comparative study with the formalin test.

To elucidate the underlying mechanisms of pathological pain, it is important and necessary to develop an animal model characterized by both spontaneous tonic pain and hyperalgesia with a prolonged duration post-tissue injury. In this report, we investigated whether the two animal models of spontaneous tonic pain (the formalin test and the bee venom test) could develop a hyperalgesia to mechanical and thermal stimuli in the injured area following subcutaneous (s.c. ) administration of the two chemical agents into the plantar surface of one hindpaw in the conscious rats. It was found that the persistent nociceptive response (flinching and lifting/licking the injected hindpaw) was monophasic and lasted for 1-2 h followed by a 72-96 h period of reduction in mechanical threshold and heat latency of withdrawal reflex in the bee venom injection area; however, in contrast, the spontaneous pain-related response was biphasic followed by a permanent hypoalgesia or analgesia in the formalin injection area although the duration and response intensity of spontaneous pain was comparable with those following bee venom treatment. Subcutaneous. bee venom injection also produced a distinct reduction of heat latency on the contralateral hindpaw, while s.c. formalin did not. On the other hand, s.c. bee venom injection produced a striking edema and redness of the plantar surface for nearly the same period as the development of hyperalgesia, while the edema and redness could not be obviously observed after the formalin treatment. In the control study, repetitive suprathreshold mechanical or heat stimuli applied to the plantar surface with or without saline treatment did not significantly influence the mechanical threshold or heat latency, suggesting that the phenomena of mechanical and heat hyperalgesia were not the effects of vehicle treatment or those of the stimulus modalities themselves. Taken together, our present results showed that in contrast to s.c. formalin injection, subcutaneous. bee venom injection produced little tissue damage but a striking inflammation accompanied by a prolonged spontaneous pain and a pronounced primary hyperalgesia to mechanical and heat stimuli in the treated hindpaw and a heat, but not mechanical, hyperalgesia in the contralateral hindpaw, implicating that bee venom model may have more advantages over the formalin test and probably other chemoirritants to study the neural mechanisms underlying pathological pain and, especially, the relationship between spontaneous pain and development of hyperalgesia.

Animals↗

PubMed1999

Pig xenogeneic antigen modification with green coffee bean alpha-galactosidase.

Green coffee bean alpha-galactosidase can cleave the terminal alpha-galactose (alphaGal) on oligosaccharides that form the major antigen on pig endothelial cells recognized by primate-specific antibodies. Studies have been made of the conditions under which it is functional (e.g. temperature, pH) and of its biochemical and immunologic effects. Pig-to-rhesus monkey vein transplants were studied to identify the efficiency of the enzyme in delaying hyperacute rejection. When a graft became occluded, biopsies were taken for light microscopy (hematoxylin and eosin), scanning electron microscopy (SEM) and immunostaining with Griffonia simplicifolia IB4 lectin (GSIB4), and for IgM, IgG and C3. alpha-Galactosidase was stable for 72-96 h and was effective at 4 degrees C and pH 6.9 (conditions of human liver graft storage), although better function was obtained at 20 degrees C and pH 6.5. Using the porcine PK15 cell assay, the cytotoxicity of human serum was reduced after treatment of the pig cells with the enzyme. In vitro studies demonstrated that porcine veins treated with alpha-galactosidase lost endothelial expression of the Gal epitope within 30 min. SEM, however, demonstrated endothelial damage beginning within 2 h, probably caused by the alpha-galactosidase, as no damage was found in phosphate-buffered saline-treated veins, where the Gal epitope was preserved for >3 h. No change was found in either group on light microscopy. In vivo studies demonstrated that patency of the alpha-galactosidase-treated veins (mean 2.5 h) was longer than that of untreated veins (0.23 h) (P < 0.01). Biopsies showed no GSIB4 lectin staining for alpha-Gal epitopes and much less IgM and C3 deposition in the treated group. Light microscopy and SEM demonstrated more severe endothelial damage, hemorrhage, and fibrin formation in the untreated group. Galactosidase is effective in removing the terminal alphaGal and delays the onset of hyperacute rejection of pig veins transplanted into monkeys. However, its effect is temporary and, on its own, its use is unlikely to prolong survival of pig organs transplanted into primates sufficiently to be of clinical value.

Animals↗

PubMed1999

The comet assay in clinical practice.

The comet assay is a single-cell gel electrophoresis technique that measures DNA damage in individual cells. Since radiation produces 3-4 times more DNA damage in well-oxygenated cells compared with hypoxic cells, this assay can quantify the fraction of radiation-resistant hypoxic cells found in many solid tumours. This paper summarizes our results with 73 accessible metastatic tumours irradiated with palliative intent. Hypoxic fractions ranged from 0.0 to 0.67 with a mean of 0.15; 62% of these advanced tumours showed a hypoxic fraction > 0.05. Comparisons between two sequential aspirates in 33 tumours gave a slope of 0.92 (r2 = 0.88), suggesting that a single aspirate is generally representative of the tumour. A limitation, however, is that the hypoxic fraction could not be measured in clinical samples given a conventional dose of 2 Gy.

Animals↗

PubMed1999

An analysis of the role of neuraminidase in the receptor-binding activity of influenza B virus: the inhibitory effect of Zanamivir on haemadsorption.

We analysed the role of neuraminidase (NA) on haemadsorption by the haemagglutinin (HA) protein of influenza B virus. The influenza B virus mutant ts-7 has a temperature-sensitive mutation in the NA protein. At high temperature, cells infected with this virus did not exhibit haemadsorption activity, but the addition of bacterial neuraminidase (bNA) restored haemadsorption activity. COS cells transfected with HA cDNAs of B/Kanagawa/73 or B/Lee/40 virus showed no evidence of haemadsorption. However, with the addition of bNA or co- transfection with NA cDNA of the B/Lee/40 virus, haemadsorption was observed. Experiments with point-mutated HA cDNAs of B/Lee/40 virus showed that two N-acetyl glycosylation sites at amino acid residues 160 and 217 were responsible for the inability of the HA protein to adsorb to erythrocytes. These results indicated that haemadsorption by the HA protein of influenza B virus required the involvement of NA. Because the NA inhibitor Zanamivir was reported not to penetrate cells, we investigated the action of this inhibitor and found that Zanamivir inhibited haemadsorption on MDCK cells infected with B/Kanagawa/73 or B/Lee/40 virus. After removing Zanamivir by washing, the addition of bNA restored the haemadsorption activity on the infected cells. Scanning electron microscopy indicated that at 0.4 microM Zanamivir, HA protein did not adsorb to erythrocytes but retained the ability to aggregate virions. However, at 4 microM Zanamivir, distinct virion formation could not be observed.

Adsorption↗

PubMed1999

[Experimental research on in vivo gene-therapy of retinoblastoma].

OBJECTIVE: To investigate the expression condition of exogenous Rb gene in nude mouse vitreous transplanted retinoblastoma(RB) and its influence on the growth of the RB tumor in vivo. METHODS: Establishing the model of RB transplantation in nude mouse vitreous, followed by constructing the retrovirus vector of Rb gene and transfecting it into the model by using liposome. The expression condition of Rb gene was analyzed by immunohistochemistry and flow cytometry. The growth condition of the RB transplantation tumor was examined ophthalmologically and pathologically. RESULTS: The exogenous Rb gene expressed in the RB transplantation tumor for at least 7 days and partially suppressed the growth of the RB tumor. The level of suppression was related with the amount of the Rb protein expressed and the time to transfect the Rb gene after the RB transplantation tumor was established. CONCLUSION: The exogenous Rb gene can express in the RB transplantation tumor and can partially suppress the growth of the RB tumor in vivo.

Animals↗

PubMed1999

[A study on the T-cell subsets and glucocorticoid receptor in children with anaphylactoid purpura].

To study the changes of T-cell subsets and glucocorticoid receptor (GCR) in children with anaphylactoid purpura. T-cell subsets and GCR were measured respectively by cytotoxicity assay and GCR radioligand-binding assay in peripheral blood lymphocytes from 35 children with anaphylactoid purpura and 35 normal children. The result showed that the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 46.03% +/- 9.40%, 31.06% +/- 6.80% and 1.23 +/- 0.33 respectively, and the GCR numbered 3060 +/- 2153 binding sites per cell in the study group, on the other hand, the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 53.11% +/- 5.40%, 35.01% +/- 4.41% and 1.52 +/- 0.26 respectively, and the GCR numbered 5210 +/- 1639 binding sites per cell in the control group. These indicate that and that patients with anaphylactoid purpura may have abnormal immunomodulations and decreased GCR numbers per cell, which may have effects on the immune dysfunctions in the pathogenesis of anaphylactoid purpura.

Adolescent↗