Biomedical subjects

C Y Chai

Publications and source records attributed to C Y Chai.

At least 19 recordsLinked to original sources

PubMed2004

Mechanisms underlying the cardioinhibitory and pressor responses elicited from the medullary neurons in the gigantocellular tegmental field of cats.

A stimulation of the gigantocellular tegmental field (FTG) in the medulla oblongata often increases systemic arterial blood pressure (SAP) and decreases heart rate (HR). We investigated if the cardioinhibitory/depressor areas, including the nucleus ambiguus (NA), the dorsal motor nucleus of vagus (DMV) and the caudal ventrolateral medulla (CVLM), underlied the functional expression of FTG neurons in regulating cardiovascular responses. In 73 chloralose-urethane anesthetized cats, the HR, SAP and vertebral nerve activity (VNA) were recorded. Neurons in the FTG, NA, DMV and CVLM were stimulated by microinjection of sodium glutamate (25 mM Glu, 70 nl). To study if the NA, DMV, and CVLM relayed the cardioinhibitory messages from the FTG, 24 mM kainic acid (KA, 100 nl) was used as an excitotoxic agent to lesion neurons in the NA, DMV or CVLM. We found that the cardioinhibition induced by FTG stimulation was significantly reduced by KA lesioning of the ipsilateral NA or DMV. Subsequently, a bilateral KA lesion of NA or DMV abolished the cardioinhibitory responses of FTG. Compared to the consequence of KA lesion of the DMV, only a smaller bradycardia was induced by FTG stimulation after KA lesion of the NA. The pressor response induced by Glu stimulation of the FTG was reduced by the KA lesion of the CVLM. Such an effect was dominant ipsilaterally. Our findings suggested that both NA and DMV mediated the cardioinhibitory responses of FTG. The pressor message from the FTG neurons might be partly working via a disinhibitory mechanism through the depressor neurons located in the CVLM.

Animals↗

PubMed2002

Nitric oxide reduces blood pressure in the nucleus tractus solitarius: a real time electrochemical study.

Increasing evidence has demonstrated that nitric oxide (NO) is involved in central cardiovascular regulation. In this study, we directly measured extracellular NO levels, in real-time, in the nucleus tractus solitarius (NTS) of anesthetized cats using Nafion/Porphyrine/o-Phenylenediamine-coated NO sensors. We found that local application of L-arginine (L-Arg) induced NO overflow in NTS and hypotension. These responses were potentiated in the vagotomized animals. Pretreatment with NO synthase (NOS)/guanylate cyclase inhibitor methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or NO scavenger hemoglobin attenuated L-Arg-induced hypotension, suggesting that exogenous supplement of NO suppressed cardiac functions through the NOS/cyclic guanosine monophosphate mechanism. The role of endogenous NO was examined after local application of N(G)-nitro-L-arginine methyl ester (L-NAME). We found that L-NAME suppressed endogenous NO levels in NTS and elicited hypertension and tachycardia. Taken together, our data suggest that NO is tonically released in the NTS to inhibit blood pressure.

Animals↗

PubMed2001

The relationship between FTL and NA, DMV or CVLM in central cardiovascular control.

The aim of the present study was to examine the relationship between the lateral tegmental field (FTL), a cardioinhibitory area, with other cardioinhibitory areas, i.e., the ambiguus nucleus (NA) and the dorsal motor nucleus of vagus (DMV) and the caudal ventrolateral medulla (CVLM), a vasopressor inhibitory area. In 55 cats anesthetized with chloralose (40 mg/kg) and urethane (400 mg/kg), the cardiovascular responses of heart rate (HR), systemic arterial blood pressure (SAP) and vertebral nerve activity (VNA) were recorded. The FTL, NA, DMV and CVLM were identified first by stimulation (rectangular pulses in 80 Hz, 0.5 ms, 50-100 microA) and then confirmed by microinjection of sodium glutamate (Glu, 0.25M, 70 nl). In studying the influence of NA, DMV, or CVLM lesion on the Gluinduced responses in FTL, kainic acid (KA, 24 mM, 100 nl) was microinjected into the NA, DMV or CVLM. FTL stimulation produced an average decrease of HR by 55%. After KA lesioning of the ipsilateral NA or the DMV, the decreased HR induced by FTL was significantly diminished. After subsequent lesion of the contralateral DMV or NA, the bradycardia of FTL was abolished. The reduction of resting HR was more intense after lesioning the NA than DMV and with the left side more than that of the right side. These studies suggest that the cardioinhibitory responses of FTL are mediated through both NA and DMV with predominance of the former, while the hypotensive effect of FTL is mediated through CVLM. The precise pathway responsible for the FTL-induced bradycardia and hypotension is to be determined.

Animals↗

PubMed2001

Aberrant expression of homeobox gene HOXA7 is associated with müllerian-like differentiation of epithelial ovarian tumors and the generation of a specific autologous antibody response.

Autologous serum antibodies to molecules that are aberrantly expressed in tumors represent potential biomarkers for early diagnosis of cancer. In this study, we identified the homeobox gene HOXA7 as encoding an antigen in epithelial tumors of the ovary. These tumors are thought to arise from the simple epithelium lining the ovarian surface, but they often resemble the specialized epithelia derived from the müllerian ducts. Expression of HOXA7 was detected in ovarian tumors exhibiting müllerian-like features and correlated with the generation of anti-HOXA7 antibodies by patients. In contrast, it was observed that healthy women lack anti-HOXA7 antibodies (P < 0.0001) and that HOXA7 expression is absent from normal ovarian surface epithelium. Interestingly, HOXA7 expression was detected in the müllerian-like epithelium lining inclusion cysts in normal ovaries and in the müllerian duct-derived epithelium of normal fallopian tubes. Furthermore, ectopic expression of HOXA7 enhanced the epithelial phenotype of immortalized ovarian surface epithelial cells, as indicated by the appearance of cobblestone morphology, induction of E-cadherin expression, and down-regulation of vimentin. These findings associate aberrant HOXA7 expression with the müllerian-like differentiation of epithelial ovarian tumors and suggest diagnostic utility of serum antibodies to HOXA7.

Antibodies, Neoplasm↗

PubMed2001

The nNOS/cGMP signal transducing system is involved in the cardiovascular responses induced by activation of NMDA receptors in the rostral ventrolateral medulla of cats.

Nitric oxide (NO) is synthesized from L-arginine by NO synthase (NOS). NO stimulates the soluble form of guanylyl cyclase (sGC) and induces accumulation of cyclic guanosine monophosphate (cGMP). The purpose of this study was to examine whether the cardiovascular responses induced by N-methyl-D-aspartate (NMDA) in the rostral ventrolateral medulla (RVLM) depend on the actions of NOS and sGC. In anesthetized cats, the extracellular NO level was measured by in vivo voltammetry using a nafion/porphyrine/o-phenylenediamine-coated carbon-fiber electrode. Microinjection of NMDA into the RVLM produced hypertension and bradycardia associated with NO formation. These NMDA-induced responses were attenuated by prior injections of 7-nitroindazole, a neuronal NO synthase (nNOS) inhibitor, and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a sGC inhibitor. These findings suggest that NO is involved in the NMDA-induced cardiovascular responses in the RVLM.

Animals↗

PubMed2001

Nitric oxide produces different actions in different areas of the periaqueductal grey in cats.

In 20 urethane-anaesthetised cats, microinjection of N-methyl-D-aspartate (NMDA) into the intermediate-lateral (IL-) or the dorsolateral (DL-) periaqueductal grey areas (PAG) of the midbrain elicited similar patterns of cardiovascular responses: increases in mean systemic arterial pressure (MSAP), heart rate (HR) and mean blood flows (F) of the common carotid and femoral arteries, accompanied with a 'hissing-howling' response. Similar increases in MSAP and Fs were induced by microinjections of S-nitroso-N-acetylpenicillamine (SNAP), a potent nitric oxide (NO) donor, on the IL-PAG (A2.5-A0.5). In contrast, microinjections of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, in the same area elicited a decrease in MSAP and Fs. On the other hand, microinjections of either SNAP or L-NAME reversed the original IL-PAG responses when injected into the DL-PAG. Pretreatments with SNAP significantly inhibited NMDA-induced responses in the DL-PAG but potentiated such responses in the IL-PAG. In contrast, pretreatments with L-NAME potentiated the NMDA-induced responses in the DL-PAG but inhibited such responses in the IL-PAG. These data suggest that NO may be a neurotransmitter or neuromodulator that exerts differential function in different defense areas, namely the IL- and the DL-PAG.

Animals↗

PubMed2001

Evaluation of percutaneous absorption and skin irritation of ketoprofen through rat skin: in vitro and in vivo study.

The influences of different mechanisms of penetration enhancers (such as menthol, azone, ethanol and nonivarnide) regarding the percutaneous absorption and skin irritation of ketoprofen formulations through rat skin were investigated by in vitro and in vivo study. The skin irritation degree at the end of the experiment (10 h) was deterinined by pathologic biopsy and colorimetry methods. In vitro, the menthol showed the most potent enhancing effect. Furthermore, the enhancement effect of a combination of menthol and nonivamide was higher than that of their individual use alone. In vivo the formulation containing 0.05% nonivantide, 5% menthol and 20% ethanol showed a higher penetration rate and an acceptable degree of skin irritation compared to a commercial product (Formax plus gel containing 3% ketoprofen), indicating that it could be used in the clinical situation.

Animals↗

PubMed2001

Enhancement of Sindbis virus self-replicating RNA vaccine potency by linkage of Mycobacterium tuberculosis heat shock protein 70 gene to an antigen gene.

Recently, self-replicating RNA vaccines (RNA replicons) have emerged as an effective strategy for nucleic acid vaccine development. Unlike naked DNA vaccines, RNA replicons eventually cause lysis of transfected cells and therefore do not raise the concern of integration into the host genome. We evaluated the effect of linking human papillomavirus type 16 E7 as a model Ag to Mycobacterium tuberculosis heat shock protein 70 (HSP70) on the potency of Ag-specific immunity generated by a Sindbis virus self-replicating RNA vector, SINrep5. Our results indicated that this RNA replicon vaccine containing an E7/HSP70 fusion gene generated significantly higher E7-specific T cell-mediated immune responses in vaccinated mice than did vaccines containing the wild-type E7 gene. Furthermore, our in vitro studies demonstrated that E7 Ag from E7/HSP70 RNA replicon-transfected cells can be processed by bone marrow-derived dendritic cells and presented more efficiently through the MHC class I pathway than can wild-type E7 RNA replicon-transfected cells. More importantly, the fusion of HSP70 to E7 converted a less effective vaccine into one with significant potency against E7-expressing tumors. This antitumor effect was dependent on NK cells and CD8(+) T cells. These results indicated that fusion of HSP70 to an Ag gene may greatly enhance the potency of self-replicating RNA vaccines.

Adjuvants, Immunologic↗

PubMed2001

Improving vaccine potency through intercellular spreading and enhanced MHC class I presentation of antigen.

The potency of naked DNA vaccines is limited by their inability to amplify and spread in vivo. VP22, a HSV-1 protein, has demonstrated the remarkable property of intercellular transport and may thus provide a unique approach for enhancing vaccine potency. Therefore, we created a novel fusion of VP22 with a model Ag, human papillomavirus type 16 E7, in a DNA vaccine that generated enhanced spreading and MHC class I presentation of AG: These properties led to a dramatic increase in the number of E7-specific CD8(+) T cell precursors in vaccinated mice (around 50-fold) and converted a less effective DNA vaccine into one with significant potency against E7-expressing tumors. In comparison, nonspreading VP22(1-267) mutants failed to enhance vaccine potency. Our data indicated that the potency of DNA vaccines may be dramatically improved through intercellular spreading and enhanced MHC class I presentation of Ag.

Adjuvants, Immunologic↗

PubMed2001

Cancer immunotherapy using a DNA vaccine encoding the translocation domain of a bacterial toxin linked to a tumor antigen.

Certain domains of bacterial toxins have been shown to facilitate translocation from extracellular and vesicular compartments into the cytoplasm. This feature represents an opportunity to enhance class I presentation of exogenous antigen to CD8(+) T cells. We investigated this notion by creating a novel fusion of the translocation domain (domain II) of Pseudomonas aeruginosa exotoxin A (ETA(dII)) with a model tumor antigen, human papillomavirus type 16 E7, in the context of a DNA vaccine. Our in vitro studies indicated that cells transfected with ETA(dII)/E7 DNA or dendritic cells pulsed with lysates containing ETA(dII)/E7 protein exhibited enhanced MHC class I presentation of E7 antigen. Vaccination of mice with ETA(dII)/E7 DNA generated a dramatic increase in the number of E7-specific CD8(+) T cell precursors ( approximately 30-fold compared with wild-type E7 DNA) and converted a less effective DNA vaccine into one with significant potency against human papillomavirus type 16 E7-expressing murine tumors via a CD8-dependent pathway. These results indicate that fusion of the translocation domain of a bacterial toxin to an antigen may greatly enhance vaccine potency.

ADP Ribose Transferases↗

PubMed2001

Enhancement of sindbis virus self-replicating RNA vaccine potency by targeting antigen to endosomal/lysosomal compartments.

Self-replicating RNA vaccines (RNA replicons) have emerged as an attractive approach for tumor immunotherapy. RNA replicons do not integrate into host chromosomes, eliminating the concern for oncogenicity associated with a DNA vaccine. In this study, we used human papillomavirus type 16 (HPV-16) E7 as a model antigen and evaluated E7-specific immunity generated by a Sindbis virus self-replicating RNA vector, SIN-rep5. Three different constructs were created to target E7 antigen to different cellular localizations: (1) E7, a cytosolic/nuclear protein; (2) Sig/E7, a secretory protein; (3) Sig/E7/LAMP-1, in which we linked the transmembrane and cytoplasmic regions of the lysosome-associated membrane protein 1 (LAMP-1) to E7 protein to target E7 to the endosomal/lysosomal compartment. We found that the RNA replicon vaccine containing the Sig/E7/LAMP-1 fusion gene generated the highest E7-specific T cell-mediated immune responses and antitumor effects relative to RNA vaccines containing either wild-type E7 or Sig/E7. Our in vitro studies demonstrated that E7 antigen from Sig/E7/LAMP-1 RNA replicon-transfected apoptotic cells can be taken up by bone marrow-derived dendritic cells (DCs) and presented more efficiently through the MHC class I pathway than wild-type E7 RNA replicon-transfected apoptotic cells. Furthermore, our data revealed that CD8(+) T cells, CD4(+) T cells, and NK cells were important for the antitumor effects generated by Sig/E7/LAMP-1 RNA vaccination. These results indicate that targeting antigen to the endosomal/lysosomal compartment via fusion to LAMP-1 may greatly enhance the potency of self-replicating RNA vaccines.

Animals↗

PubMed2001

Enhancement of DNA vaccine potency by linkage of antigen gene to a gene encoding the extracellular domain of Fms-like tyrosine kinase 3-ligand.

Recently, Flt3 (Fms-like tyrosine kinase 3)-ligand has been identified as an important cytokine for the generation of professional antigen-presenting cells (APCs), particularly dendritic cells (DCs). A recombinant chimera of the extracellular domain of Flt3-ligand (FL) linked to a model antigen may potentially target the antigen to DCs and their precursor cells. Using human papillomavirus-16 E7 as a model antigen, we evaluated the effect of linkage to FL on the potency of antigen-specific immunity generated by naked DNA vaccines administered intradermally via gene gun. We found that vaccines containing chimeric FL-E7 fusion genes significantly increased the frequency of E7-specific CD8+ T cells relative to vaccines containing the wild-type E7 gene. In vitro studies indicated that cells transfected with FL-E7 DNA presented E7 antigen through the MHC class I pathway more efficiently than wild-type E7 DNA. Furthermore, bone marrow-derived DCs pulsed with cell lysates containing FL-E7 fusion protein presented E7 antigen through the MHC class I pathway more efficiently than DCs pulsed with cell lysates containing wild-type E7 protein. More importantly, this fusion converted a less effective vaccine into one with significant potency against established E7-expressing metastatic tumors. The FL-E7 fusion vaccine mainly targeted CD8+ T cells, and antitumor effects were completely CD4 independent. These results indicate that fusion of a gene encoding the extracellular domain of FL to an antigen gene may greatly enhance the potency of DNA vaccines via CD8-dependent pathways.

Animals↗

PubMed2001

Congenital prepubic sinus: a variant of dorsal urethral duplication suggested by immunohistochemical analysis.

PURPOSE: Congenital prepubic sinus is a rare disorder of uncertain etiology. Immunohistochemical staining is used to elucidate the etiology of the sinus. MATERIALS AND METHODS: We treated 5 patients with congenital prepubic sinus. A sinogram delineated the tract, which was then excised. In addition to routine hematoxylin and eosin stain of the 5 specimens, immunohistochemical analysis was also performed with smooth muscle and sarcomeric actin, high (34betaE12) and low molecular weight cytokeratin (35betaH11), and cytokeratin 7 antibodies. RESULTS: The 2 females and 3 males were 1 month to 14 years old. All patients had presented with purulent discharge from the sinus opening. Hematoxylin and eosin stain demonstrated transitional and squamous epithelium lining the sinus. Immunohistochemical study showed that the stain with 3 cytokeratin antibodies was moderately to strongly positive in all patients at the proximal end, low molecular weight cytokeratin weakly to moderately positive and cytokeratin 7 weakly positive to negative in 4 at the distal end. The results suggested that the lining epithelium was transitional proximally and squamous distally. An exception was a female patient who had the shortest tract lined with squamous epithelium only. Furthermore, smooth muscle but not sarcomeric actin demonstrated smooth muscle bundles around the sinus tract in 4 patients. CONCLUSIONS: The existence of transitional epithelium in the proximal part of the sinus and presence of smooth muscle bundles around it reinforce the theory that congenital prepubic sinus is a variant form of dorsal urethral duplication.

Adolescent↗

PubMed2001

Activation of noradrenergic mechanism attenuates glutamate-induced vasopressor responses in the pons and medulla of cats in vivo.

1. Using anesthetized cats, the authors examined the noradrenergic modulation of the glutamate induced pressor and depressor responses in various brainstem areas, including pontine gigantocellular tegmental field (FTG), dorsomedial medulla (DM), rostral ventrolateral medulla (RVLM), and caudal ventrolateral medulla (CVLM). 2. Unilateral microinjection of L-glutamate (Glu, 3 nmol in 30 nL saline) into FTG, DM and RVLM produced an increase in systemic arterial pressure (SAP) and a decrease in heart rate (HR), while into CVLM produced decreases of SAP and HR. 3. Application of norepinephrine (NE) into the pressor areas (0.05 to 5 nmol) did not alter the resting SAP and HR, but significantly attenuated the Glu-induced pressor response with an order of potency: FTG > DM > RVLM. In the depressor CVLM, NE alone produced a dose-dependent decrease of resting SAP and HR, but did not affect the Glu-induced depressor responses. 4. The involvement of different adrenoceptor subtypes was further investigated by application of selective adrenoceptor agonists including phenylephrine (alpha1), clonidine (alpha2), and isoproterenol (beta). Responses to these agonists are similar to those elicited by NE, except that only alpha-adrenoceptor agonists could antagonize the Glu-induced pressor responses of the RVLM. 5. Our observations indicate that NE not only inhibits the pressor mechanisms in various brainstem areas but also elicits a direct depressor response in CVLM. These findings also suggest that NE acts more likely a neurotransmitter, rather than a modulator, in the CVLM.

Adrenergic alpha-Agonists↗

PubMed2001

Role of nitric oxide on pressor mechanisms within the dorsomedial and rostral ventrolateral medulla in anaesthetized cats.

1. The role of nitric oxide (NO) in central cardiovascular regulation and the correlation between NO and glutamate-induced mechanisms is not clear. Microinjection of glutamate (3 nmol/30 nL) into dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM) increased arterial blood pressure (BP) and sympathetic vertebral nerve activity (VNA). Thus, in the present study, we examined the modulation by NO of glutamate-induced pressor responses in the DM and RVLM of cats. 2. Histochemical methods using nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) as a marker to stain neurons containing NO synthase (NOS), showed positive findings of NOS in both the DM and RVLM. 3. Microinjection of N(G)-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, into the DM or RVLM did not alter resting BP and VNA, but it did cause a dose-dependent attenuation of glutamate-induced pressor responses. Interestingly, the increase in NO levels that resulted from pretreatment with L-arginine (L-Arg) or sodium nitroprusside (SNP) did not alter resting BP and VNA, but still inhibited glutamate-induced pressor responses in the DM and RVLM in a dose-dependent manner. 4. We also examined whether NO modulated the pressor responses induced by activation of different excitatory amino acid receptors. N-Methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) were used. Consistent with the results from the initial glutamate studies, we observed that not only L-NAME, but also L-Arg and SNP attenuated pressor responses induced by NMDA and AMPA. No difference was found between the effects of NO on NMDA- and AMPA-induced pressor responses. 5. To investigate the possibility of a loss of agonist selectivity, the effects of D-2-amino-5-phosphonovalerate (D-AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) on AMPA and NMDA responses in the DM were examined. The results showed that CNQX did not alter NMDA-induced pressor responses, while D-AP5 failed to alter AMPA-induced responses. 6. Our results suggest that activation of the glutamate-induced pressor mechanism is regulated by changes in NO levels in the DM and RVLM. This implies that NO may play a permissive role to allow operation of the glutamate-activation mechanism.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2001

A prospective study of p53 expression and its correlation with clinical response of radiotherapy in nasopharyngeal carcinoma.

OBJECTIVES/HYPOTHESIS: Nasopharyngeal carcinoma (NPC) is a common malignant neoplasm of the head and neck that occurs in people in the southeastern Asian area, including Taiwan. The significant association of p53 expression in NPC suggested that p53 overexpression seemed to occur at an early stage in the development of NPC. Alterations of p53 status were probably the most commonly encountered in head and neck carcinomas, and there was extensive evidence that p53 status might determine tumor response to therapy. Ionizing radiation was studied extensively for the relationship between its damaging effect and p53 status in human cancer cells. STUDY DESIGN: This study was carried out to investigate whether there was any correlation between overexpression of p53 protein and locoregional tumor response in patients with NPC treated with 7000 cGy of radiotherapy. METHODS: Sixty-eight patients (50 males, 18 females) with NPC who were diagnosed and treated with radiotherapy were studied prospectively. Before they had received a radiation dose of 7000 cGy in 35 fractions, five fractions a week, p53 status from a nasopharyngeal biopsy was studied using immunohistochemical staining (IHC). RESULTS: The locoregional response rate of primary tumor was analyzed statistically. Forty-seven patients (69.1%) showed positive p53 staining in their tumors. There were 5 positive stains in 6 squamous cell carcinomas (SCC; 83.3%), 34 positive in 53 non-keratinizing carcinomas (NKC; 64.2%), and 8 positive in 9 undifferentiated carcinomas (UC; 88.9%). The mean ages for patients with three different histopathologies were 48.5, 46.1, and 61.1 years. There were 8 patients (7 positive stains, 1 negative stain) with residual tumor after radiotherapy and all were NKC (6 males, 2 females). Therefore, the clinical response rate of primary tumor was 85.1% in positive p53 immunostaining (40 of 47 cases), 95.2% in those with no immunostaining (20 of 21 cases); the former was poorer in locoregional tumor response than the latter, but there was no significant difference (P > .05, chi2 test). CONCLUSIONS: We conclude that there is no statistically significant correlation in locoregional response of primary tumor between p53 overexpression and radiotherapy in patients with NPC (P > .05, Fisher exact test).

Adolescent↗

PubMed2001

Enhancement of sindbis virus self-replicating RNA vaccine potency by linkage of herpes simplex virus type 1 VP22 protein to antigen.

Recently, self-replicating and self-limiting RNA vaccines (RNA replicons) have emerged as an important form of nucleic acid vaccines. Self-replicating RNA eventually causes lysis of transfected cells and does not raise the concern associated with naked DNA vaccines of integration into the host genome. This is particularly important for development of vaccines targeting proteins that are potentially oncogenic. However, the potency of RNA replicons is significantly limited by their lack of intrinsic ability to spread in vivo. The herpes simplex virus type 1 protein VP22 has demonstrated the remarkable property of intercellular transport and provides the opportunity to enhance RNA replicon vaccine potency. We therefore created a novel fusion of VP22 with a model tumor antigen, human papillomavirus type 16 E7, in a Sindbis virus RNA replicon vector. The linkage of VP22 with E7 resulted in a significant enhancement of E7-specific CD8+ T-cell activities in vaccinated mice and converted a less effective RNA replicon vaccine into one with significant potency against E7-expressing tumors. These results indicate that fusion of VP22 to an antigen gene may greatly enhance the potency of RNA replicon vaccines.

Animals↗

PubMed2001

Dorsomedial medulla is more susceptible than rostral ventrolateral medulla to hypoxic insult in cats.

We investigated the responses of systemic arterial pressure and vertebral sympathetic nerve activity to glutamate microinjections (0. 1 M, 70 nl) in the dorsomedial (DM) and the rostral ventrolateral medulla (RVLM) before hypoxia and after reoxygenation (posthypoxia) after various degrees of hypoxia in anesthetized cats. Hypoxia was produced by ventilating 5% O(2) and 95% N(2) for different durations (hypoxia I-III). In intact cats, the glutamate-induced systemic arterial pressure and vertebral nerve activity responses of the DM were depressed after all degrees of hypoxia. Posthypoxic depression in the RVLM, however, was not observed until hypoxia II and III. Precollicular decerebration prevented depression in the RVLM, but, for the DM, it was effective only for hypoxia I. Baro- and chemoreceptor denervation abolished all posthypoxic depression in both the DM and the RVLM. Pressor responses to tyramine (100-400 microg/kg iv) remained unchanged after all degrees of hypoxia. These results suggest that the DM is more susceptible to hypoxia than the RVLM. The peripheral baro- and chemoreceptors and the suprapontine structures apparently play an important role in posthypoxic depression. Moreover, the depression is not due to the postganglionic norepinephrine depletion.

Animals↗