Biomedical subjects

J Zhu

Publications and source records attributed to J Zhu.

At least 217 records · Page 12Linked to original sources

PubMed2000

DNA immunization utilizing a herpes simplex virus type 2 myogenic DNA vaccine protects mice from mortality and prevents genital herpes.

A gene transfer vector for DNA immunization was developed in which the promoter was derived from the murine muscle creatine kinase (MCK) gene; a gene expressed only in differentiated skeletal muscle. In vitro, we observed high-level, but unrestricted, gene expression from the cytomegalovirus (CMV) promoter unlike expression from the MCK promoter which was weak but restricted to myofibers. A myogenic DNA vaccine (MDV) that encoded the glycoprotein D gene from herpes simplex virus type-2 (HSV-2) was used to DNA immunize mice. MDV immunization resulted in virus specific immunity that protected HSV-2 infected mice from mortality and prevented the development of genital herpes. Therefore, we conclude that high-level gene expression or the use of a strong transcription unit was not a prerequisite for an efficacious DNA vaccine and the use of a nonviral tissue specific promoter could suffice.

Animals↗

PubMed2000

A new synthesis of p-hydroxy phenylglycine and some analogues from p-benzoquinone

[reaction: see text] A new route to p-hydroxy phenylglycine and N-substituted analogues has been developed starting from p-benzoquinone. 1,2-Addition of methyl lithioacetate to p-benzoquinone and subsequent quenching of the oxygen anion with methyl chloroformate, followed by an elimination-addition reaction with an appropriate amine, resulted in the desired amino acid derivatives. A diastereoselectivity of 60% was achieved using 8-phenylmenthyl acetate as the chiral auxiliary.

Journal Article↗

PubMed2000

Differential expression and regulation by 20-hydroxyecdysone of mosquito ultraspiracle isoforms.

Ultraspiracle (USP), the insect homologue of the vertebrate retinoid X receptor, is an obligatory dimerization partner for the ecdysteroid receptor (EcR). Two USP isoforms, USP-A and USP-B, with distinct N-termini, occur in the mosquito Aedes aegypti. In the fat body and ovary, USP-A mRNA is highly expressed during the pre- and late vitellogenic stages, corresponding to a period of low ecdysteroid titer, while USP-B mRNA exhibits its highest levels during the vitellogenic period, correlating with a high ecdysteroid titer. Remarkably, 20-hydroxyecdysone (20E) has opposite effects on USP isoform transcripts in in vitro fat body culture. This steroid hormone upregulates USP-B transcription and its presence is required to sustain a high level of USP-B expression. In contrast, 20E inhibits activation of USP-A transcription. Although EcR.USP-A recognizes the same ecdysteroid-responsive elements, EcR.USP-B binds them with an affinity twofold higher than that of EcR.USP-A. Likewise, EcR.USP-B transactivates a reporter gene in CV-1 cells twofold more strongly than EcR.USP-A. These results suggest that USP-B functions as a major heterodimerization partner for EcR during the vitellogenic response to 20E in the mosquito.

Aedes↗

PubMed2000

AHR38, a homolog of NGFI-B, inhibits formation of the functional ecdysteroid receptor in the mosquito Aedes aegypti.

In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of numerous devastating human diseases. After ingestion of blood, 20-hydroxyecdysone activates yolk protein precursor (YPP) genes in the metabolic tissue, the fat body. An important adaptation for anautogenicity is the previtellogenic developmental arrest (the state-of-arrest) preventing the activation of YPP genes in previtellogenic females prior to blood feeding. Here, we show that a retinoid X receptor homolog, Ultraspiracle (AaUSP), which is an obligatory partner in the functional ecdysteroid receptor, exists at the state-of-arrest as a heterodimer with the orphan nuclear receptor AHR38, a homolog of Drosophila DHR38 and nerve growth factor-induced protein B. Yeast two-hybrid and glutathione S-transferase pull-down assays demonstrate that AHR38 can interact strongly with AaUSP. AHR38 also disrupts binding of ecdysteroid receptor to ecdysone response elements. Cell co-transfection of AHR38 with AaEcR and AaUSP inhibits ecdysone-dependent activation of a reporter gene by the ecdysteroid receptor. Co-immunoprecipitation experiments indicate that AaUSP protein associates with AHR38 instead of AaEcR in fat body nuclei at the state-of-arrest.

Aedes↗

PubMed2000

Effects of total pathogen burden on coronary artery disease risk and C-reactive protein levels.

Infection and inflammation have been suggested to play roles in coronary artery disease (CAD). We hypothesized that: (1) CAD risk is associated with the aggregate number of pathogens (pathogen burden), and (2) increased pathogen burden is associated with elevated levels of C-reactive protein (CRP), a marker of inflammation. We evaluated 233 patients for CAD. Blood samples from each patient were tested for immunoglobulin-G (IgG) antibodies to cytomegalovirus (CMV), Chlamydia pneumoniae, hepatitis A virus (HAV), herpes simplex virus type 1 (HSV-1) and HSV type 2 (HSV-2), and for the CRP levels. Of the 233 study subjects, 68% had evidence of CAD by coronary angiography. Although the prevalence of seropositivity for each pathogen tended to be higher in the patients with CAD than those without, only the association between CAD and seropositivity to HAV was significant in multivariate analysis. Over 75% of study subjects had been exposed to > or =3 of the 5 pathogens tested, and analysis determined that increasing pathogen burden was significantly associated with increasing CAD risk, even after adjustment for traditional CAD risk factors. The prevalence of CAD was 48%, 69%, and 85% in individuals with antibodies to < or =2 pathogens, to 3 or 4 pathogens, and to 5 pathogens, respectively. A similar association between increasing pathogen burden and CRP levels was also found. The pathogen burden remained a significant predictor of CRP levels after multivariate analysis. Our data suggest that infection does play a role in the genesis of atherosclerosis. However, the risk posed by infection is related to the pathogen burden that may contribute to CAD through inflammatory responses.

Adult↗

PubMed2000

Rolipram suppresses experimental autoimmune neuritis and prevents relapses in Lewis rats.

Rolipram, a phosphodiesterase type 4 inhibitor, can markedly down-regulate antigen-driven T cell proliferation and suppress TNF-alpha production in vitro and in vivo. Here we report the effects of Rolipram on experimental autoimmune neuritis (EAN), which can be induced by immunization with myelin components of the peripheral nervous system (PNS) combined with Freund's complete adjuvant (FCA), and which represents a CD4+ T cell-mediated animal model for human Guillain-Barré syndrome. EAN induced in Lewis rats by inoculation with the PNS P2 protein peptide 57-81 and FCA was strongly suppressed by Rolipram administered twice daily intraperitoneally from day 9 post immunization (p.i.), i.e. after onset of clinical EAN. Suppression of EAN was associated with down-regulated myelin antigen-induced T cell responses as well as down-regulated IFN-gamma and TNF-alpha production. A relapse of clinical EAN occurred upon treatment of a short duration (7 days), while prolongation of treatment resulted in the prevention of clinical EAN relapse. There was no relationship between clinical EAN relapse and high levels of TNF-alpha. The immunomodulatory effects of Rolipram call for further research into the potential role of drugs acting on the immune system in the treatment of autoimmune diseases.

Animals↗

PubMed2000

Dicyclomine, an M1 muscarinic antagonist, reduces infarct volume in a rat subdural hematoma model.

The rat subdural hematoma (SDH) model produces a zone of ischemic brain damage within the hemisphere beneath the SDH. Previous studies have measured large increases in extracellular acetylcholine during cerebral ischemia in the rat. We examined infarct volume after selectively blocking muscarinic M1 receptors with dicyclomine during SDH. Rats were anesthetized with isoflurane (2%), intubated, and femoral artery and vein cannulated. Autologous blood (0.375 ml) was injected (0.05 ml/min) under the dura of the right parietal cortex. Dicyclomine (5 mg/kg, i.v.) was injected at 5 min after and again at 2 h after completion of the subdural blood infusion. Blood pressure and intracranial pressure (ICP) were continuously measured. At 4 h after SDH rats were euthanized, brains sectioned, and immunoreacted with glia fibrillary acidic protein. Cortical infarct volume was quantified in coronal brain sections at 0.7-mm intervals from +1.0 mm to -3.9 mm relative to bregma. Infarct volume in drug-treated rats (n = 10) 22.1 +/- 6.99 mm3 was significantly smaller (p < 0.02) than vehicle treated rats (n = 10) 56.7 +/- 9.59 mm3. ICP, blood pressure and cerebral perfusion pressure were not significantly different between groups. These data suggest that activation of M1 muscarinic receptors during an ischemic event may contribute to the development of subsequent pathology.

Animals↗

PubMed2000

High inflammation and mild demyelination in the peripheral nervous system induced by an intraneural injection of RR interleukin-4.

To examine the direct effects of IL-4 on peripheral nervous system (PNS) we injected recombinant rat IL-4 (rrIL-4) into the sciatic nerve of normal adult Lewis rats. Histopathological and immunohistochemical observations revealed that 1 day after injection, a large number of macrophages and MHC class II-positive cells appeared within both the perineurium and endoneurium. Only few CD4(+)and CD8(+)T cells existed in the endoneurium. From day 4 to day 7, we observed a gradual decline of inflammation, but the number of infiltrates in rrIL-4 injected nerves was significantly higher compared with sterile PBS-injected control group. On the contrary, demyelination affected significantly fewer nerve fibres in the rrIL-4-injected nerves compared with control group on day 7. Intraneural injection of rrIL-4 results in high grade inflammation and mild demyelination in the PNS.

Animals↗

PubMed2000

Enhancement of acute phase and inhibition of chronic phase of experimental autoimmune neuritis in Lewis rats by intranasal administration of recombinant mouse interleukin 17: potential immunoregulatory role.

Experimental autoimmune neuritis (EAN) is a CD4(+) T-cell-mediated demyelinating disease of the peripheral nervous system (PNS). We examined the effect of recombinant mouse interleukin 17 (rmIL-17) on chronic EAN induced in Lewis rats by inoculation of P2 57-81 peptide in Freund's complete adjuvant. Animals were treated nasally for 6 days with either 0.1 or 0.9 microg/rat/day rmIL-17 from the onset of neurological signs, i.e., days 9 to 14 postimmunization (p.i.). Prolonged follow-up demonstrated a chronic course in control and rmIL-17-treated rats. Treated rats had more severe disease initially (days 18-36 p.i.) with a stronger enhancing effect observed with the higher rmIL-17 dose. At day 19 rmIL-17-treated rats showed increased infiltration of inflammatory cells into the sciatic nerve, more severe demyelination, augmented proliferation of regional lymph node cells, and increased serum levels of tumor necrosis factor-alpha. After the initial phase of disease enhancement the IL-17-treated EAN rats improved gradually and ultimately recovered completely, whereas the control EAN rats remained affected until the end of the observation (day 120 p.i.). The lower dose of rmIL-17 induced an earlier recovery from clinical deficits than the higher one. The results indicate that IL-17 plays an immunoregulatory role in chronic EAN which could have implications for immunomodulatory treatments of chronic autoimmune disease of the PNS.

Acute Disease↗

PubMed2000

Postinjury administration of L-deprenyl improves cognitive function and enhances neuroplasticity after traumatic brain injury.

The rat model of combined central fluid percussion traumatic brain injury (TBI) and bilateral entorhinal cortical lesion (BEC) produces profound, persistent cognitive deficits, sequelae associated with human TBI. In contrast to percussive TBI alone, this combined injury induces maladaptive hippocampal plasticity. Recent reports suggest a potential role for dopamine in CNS plasticity after trauma. We have examined the effect of the dopamine enhancer l-deprenyl on cognitive function and neuroplasticity following TBI. Rats received fluid percussion TBI, BEC alone, or combined TBI + BEC lesion and were treated once daily for 7 days with l-deprenyl, beginning 24 h after TBI alone and 15 min after BEC or TBI + BEC. Postinjury motor assessment showed no effect of l-deprenyl treatment. Cognitive performance was assessed on days 11-15 postinjury and brains from the same cases examined for dopamine beta-hydroxylase immunoreactivity (DBH-IR) and acetylcholinesterase (AChE) histochemistry. Significant cognitive improvement relative to untreated injured cases was observed in both TBI groups following l-deprenyl treatment; however, no drug effects were seen with BEC alone. l-Deprenyl attenuated injury-induced loss in DBH-IR over CA1 and CA3 after TBI alone. However, after combined TBI + BEC, l-deprenyl was only effective in protecting CA1 DBH-IR. AChE histostaining in CA3 was significantly elevated with l-deprenyl in both injury models. After TBI + BEC, l-deprenyl also increased AChE in the dentate molecular layer relative to untreated injured cases. These results suggest that dopaminergic/noradrenergic enhancement facilitates cognitive recovery after brain injury and that noradrenergic fiber integrity is correlated with enhanced synaptic plasticity in the injured hippocampus.

Acetylcholinesterase↗

PubMed2000

Significantly increased expression of beta-glucuronidase in the central nervous system of mucopolysaccharidosis type VII mice from the latency-associated transcript promoter in a nonpathogenic herpes simplex virus type 1 vector.

Herpes simplex virus (HSV) has the ability to establish life-long latent infections in postmitotic neurons and to remain transcriptionally active, continuously expressing latency-associated transcripts (LAT) while producing minimal disease. These properties have made HSV an excellent candidate for neuronal gene transfer. Previously, we have shown that in mucopolysaccharidosis type VII mice (MPS VII, beta-glucuronidase deficiency) the LAT promoter is capable of expressing beta-glucuronidase (GUSB) in the trigeminal ganglion and the brainstem after latency is established. However, the number of neurons expressing GUSB is much lower than the number expressing 2-kb LAT following a wild-type virus infection. In this study, we have evaluated the effect of the position of the coding sequence relative to the LAT promoter on beta-glucuronidase gene expression in the central nervous system (CNS). Non-neurovirulent (ICP-34.5-deleted HSV-1) vectors were used, allowing direct intracranial injection. Significantly more GUSB activity was detected in brains of MPS VII mice inoculated with a recombinant virus (HSV-LAT-GUSB-JS) in which the GUSB cDNA was inserted near the LAT promoter, compared to viruses where it was inserted farther downstream in either the LAT exon 1 or overlapping exon 1 and the 2-kb LAT intron. This vector produced more than 100 times the number of positive cells than the other constructs. During acute infection, the distribution of viral replication differed from the distribution of GUSB enzyme expression. Viral antigen was predominately present in cells around the site of injection in the caudate putamen and in ependymal cells lining the ventricles. In contrast, GUSB expression was present mainly in cells of the thalamus and hypothalamus, which did not exhibit viral antigen, suggesting that GUSB enzyme activity was expressed from latently but not acutely infected neuronal cells. This vector design should be useful for high-level expression of various genes in the CNS.

Animals↗

PubMed2000

Isolation of fetal nucleated red blood cells from maternal blood.

To find a simple, effective method of isolating fetal cells from maternal peripheral blood for prenatal diagnosis, 45 women were studied with their gestation being 6-14 weeks and age 21-30 years. The fetal cells were isolated from maternal blood by using discontinuous density gradient centrifugation. Some of the isolated cells were made smear and counted under the microscope; others were used for predicting fetal sex by PCR amplification of Y chromosome specific DYZ1 gene. The major cells in the upper separation interface were lymphocytes and monocytes, with occasionally seen nucleated red blood cells (NRBC); while those in the middle separation interface were neutrocytes, with NRBC scattering. The ratio of NRBC/nucleated cells was 1.98 +/- 0.28 x 10(-5). There was no significant difference between the first and second trimester (P > 0.05). The amount of isolated fetal cells was sufficient for prenatal genetic diagnosis. Male pregnancy was correctly predicted in 10 out of 13 cases. It is concluded that the method of discontinuous density gradient centrifugation was of considerable importance in the development of non-invasive prenatal genetic diagnosis.

Adult↗

PubMed2000

Nucleocytoplasmic shuttling and the control of NF-AT signaling.

The nuclear factors of activated T cells (NF-ATs) constitute a family of transcription factors that transduce calcium signals in the immune, cardiac, muscular and nervous systems. Like their distant relatives of the Rel family, including NF-kappaB, NF-ATs are cytoplasmic in resting cells and activated by means of induced nuclear import. Unlike NF-kappaB, however, NF-ATs show highly dynamic nuclear shuttling properties that have important implications for graded signaling by these molecules. This review focuses on recent advances in deciphering mechanisms by which calcium signaling regulates the nucleo-cytoplasmic shuttling,and therefore transactivation functions of the NF-ATs. These discoveries highlight the interplay between nuclear import and export signals on NF-ATs, and the roles of the calcium-activated phosphatase calcineurin and NF-AT kinases in controlling the activity of these signals. They also reveal that NF-ATs, as well as other transcription factors controlled at the level of nuclear import, face the very real prospect of futile cycling across the nuclear envelope as a consequence of conflicting nuclear import and export signals. We discuss the molecular mechanisms by which calcineurin suppresses futile cycling, as well as the major challenges to our understanding of NF-AT signaling in diverse biological systems.

Animals↗

PubMed2000

Voltammetric determination of mifepristone at a DNA-modified carbon paste electrode.

A new strategy for the preparation of a DNA-modified carbon paste electrode is developed. It is found that the anodic response of mifepristone is greatly enhanced at the dsDNA-modified carbon paste electrode comparing with that obtained at the bare electrode, while the response at a ssDNA-modified electrode is similar to bare electrode. So the dsDNA-modified electrode is employed as a sensitive biosensor for the detection of mifepristone. A linear dependence of the peak currents on the concentration is observed in the range 2.0 x 10(-7) approximately 2.0 x 10(6) mol/L, with a detection limit of 1.0 x 10(-7) mol/L. The relative standard deviation is 4.3% for six successive determinations of 1.0 x 10(6) mol/L mifepristone. The determination of mifepristone tablets is carried out and satisfactory results are obtained.

Biosensing Techniques↗

PubMed2000

Serotonin released from intestinal enterochromaffin cells mediates luminal non-cholecystokinin-stimulated pancreatic secretion in rats.

BACKGROUND & AIMS: Similar to cholecystokinin (CCK), non-CCK-dependent duodenal factors stimulate vagal mucosal afferent fibers to mediate pancreatic enzyme secretion via a common cholinergic pathway. We tested the hypothesis that 5-hydroxytryptamine (5-HT) released from enterochromaffin (EC) cells plays an important role in the transduction of luminal information to the central nervous system via vagal afferent fibers to mediate pancreatic secretion. METHODS: Pancreatic secretions were examined in conscious rats after intragastric administration of chopped rodent chow in the presence and absence of CCK or 5-HT(3) and 5-HT(2) antagonists. Pancreatic responses to intraduodenal administration of maltose, hyperosmolar NaCl, and light mucosal stroking were examined in rats pretreated with various pharmacological antagonists or after surgical or chemical ablation of vagal and 5-HT neural pathways. RESULTS: Administration of L364, 718 inhibited 54% of pancreatic protein secretion evoked by intragastric administration of rodent chow. L364,714 and ICS 205-930, a 5-HT(3) antagonist, combined produced a 94% inhibition. Vagal afferent rootlet section eliminated pancreatic secretions evoked by intraduodenal stimuli. p-Chlorophenylalanine, a 5-HT synthesis inhibitor, but not 5,7-hydroxytryptamine, a 5-HT neurotoxin, also eliminated the pancreatic response to these luminal stimuli. The 5-HT(3) antagonist markedly inhibited pancreatic secretion induced by maltose and hyperosmolar NaCl. 5-HT(2) and 5-HT(3) antagonists combined inhibited the pancreatic response to light stroking of the mucosa. CONCLUSIONS: Luminal factors such as osmolality, disaccharides, and mechanical stimulation stimulated pancreatic secretion via intestinal vagal mucosal afferent fibers. It is likely that 5-HT originating from intestinal EC cells activated 5-HT(3) and 5-HT(2) receptors on vagal afferent fibers to mediate luminal factor-stimulated pancreatic secretion.

5,7-Dihydroxytryptamine↗

PubMed2000

K(+) channel-blocking alkoxypsoralens inhibit the immune response of encephalitogenic T line cells and lymphocytes from Lewis rats challenged for experimental autoimmune encephalomyelitis.

Alkoxypsoralens, known as DNA photomodifying agents, have been shown to block voltage-dependent K(+) channels (Kv) as well as to alleviate functional deficits in certain multiple sclerosis (MS) patients in a manner similar to 4-aminopyridine. Since Kv channel blockers are known to inhibit T cell-mediated immune responses both in vitro and in vivo, we investigated the effects of three alkoxypsoralens, 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and 5,8-diethoxypsoralen (H37), on the following parameters: (1) whole-cell K(+) currents of encephalitogenic, myelin basic protein-specific memory T cell line cells (MBP-TCLC) derived from Lewis rats as measured by patch-clamp technique, (2) proliferation of MBP-TCLC and lymph node cells (LNC) from Lewis rats challenged for experimental autoimmune encephalomyelitis (EAE) by immunisation with spinal cord homogenate as measured by 3H-thymidine incorporation, (3) interferon-gamma (IFN-gamma) secretion of MBP-TCLC as measured by ELISA, and (4) IFN-gamma gene expression of LNC as measured by quantitative reverse transcription polymerase chain reaction (RT-PCR) with ELISA-detection. The examined alkoxypsoralens exhibited suppressive effects on the measured parameters with the same sequence of efficacy: H37>5-MOP>8-MOP. We, therefore, conclude that Kv channel-blocking alkoxypsoralens interfere with voltage-controlled signal transduction in lymphocytes and might thereby suppress immune responses in autoimmune diseases of the central nervous system and most likely also in other autoimmune disorders. Thus, alkoxypsoralens, especially the non-phototoxic substance H37, are new candidates for further studies on K(+) channel blocking immunosuppressive drugs. The agents may exert a dual beneficial effect on demyelinating diseases like MS, because they could attenuate the inflammatory process and improve axonal conductivity.

4-Aminopyridine↗

PubMed2000

A practical simulated annealing program and its application to quantitative CBED pattern matching

A modified simulated annealing (SA) program is presented (source code available from the authors). The program was used for the refinement procedure in quantitative convergent beam diffraction (QCBED). Considering the practical situation in QCBED, three modifications have been made to the conventional SA algorithm. First, a most probable search boundary (MPB) was suggested, which guarantees the program to search mainly within the MPB, but allows it also to go out of the boundary sometimes. Secondly, the MPB was set to shrink during the minimization. This algorithm decreases the computing time significantly. Thirdly, a more meaningful stop criterion was adopted using the nominal physical precision of each refinement parameter. The feasibility and the efficiency of the modified program were tested using both calculated and experimental CBED patterns. The presented program is proved to be capable of high performance.

Journal Article↗

PubMed2000

Formation and decompositions of chloride adduct ions,

The ability to promote chloride-attachment ions of the form [M + Cl]- in negative ion electrospray ionization mass spectrometry (ESI-MS) has been developed using chlorinated solvents such as chloroform and carbon tetrachloride. This approach expands the current capabilities of negative ion ESI-MS by enabling detection of analytes that lack acidic sites and thus exhibit weak [M - H]- signals. In contrast to the remote-site collision-induced dissociation (CID) often observed in positive ion ESI-MS/MS for alkali metal cation adducts, the decomposition of chloride adducts usually proceeds via competitive dissociations to form Cl-, which is not structurally informative, or [M - H]-. The latter can provide structural information via consecutive decompositions. For compounds having higher gas-phase acidities than HCl, a low CID collision energy can promote the formation of [M - H]-, whereas for the majority of compounds with lower gas phase acidities than HCl, higher collision energies generally improve the relative yield of [M- H] . Because chloride attachment occurs primarily at electrophilic hydrogens, the daughter ion ratio, Cl-/[M - H]-, depends primarily upon the difference in gas phase acidity between the analyte molecule and HCl. At higher collision energies, entropic factors take on increased importance in determining the product ratio. The difference between the deltaS(0) terms for formation of Cl and formation of [M - H]- has been estimated for a series of substituted phenols and a series of acetic acid analogs. Finally, a novel neutral loss of CH3Cl from glycerophosphocholine and from ganglioside GM3 methyl ester is reported.

Journal Article↗