DSpace community: 附設醫院醫學研究部

Enhancement of Vaccinia Vaccine Potency by Linkage of Tumor Antigen Gene to Gene Encoding Calreticulin

title: Enhancement of Vaccinia Vaccine Potency by Linkage of Tumor Antigen Gene to Gene Encoding Calreticulin abstract: Vaccinia vaccines have become important vectors for antigen- specific immunotherapy. Calreticulin has been shown to enhance MHC class I presentation of linked peptide/protein and may be useful for antigen- specific cancer treatment. An innovative vaccine administering antigen linked to calreticulin via a vaccinia vector may generate a potent antigen -specific antitumor response. We tested the efficacy of linking calreticulin (CRT) to model antigen human papilloma virus type 16 (HPV-16) E7 in the context of a vaccinia vaccine (Vac-CRT/E7). Intraperitoneal vaccination of C57BL/6 mice with Vac-CRT/E7 led to a dramatic increase in E7-specific IFN-gamma-secreting CD8(+) T cells and a potent antitumor effect against E7-expressing tumors compared to immunization with Vac-E7 or Vac-CRT. When compared to other chimeric vaccinia vaccines employing various intracellular targeting strategies previously developed in our lab , Vac-CRT/E7 elicited the highest number of E7-specific CD8(+) T cells. Thus, vaccination with vaccinia expressing CRT linked to a tumor antigen may represent an advantageous strategy for cancer immunotherapy. (C) 2004 Elsevier Ltd. All rights reserved.

Renal Afferent Signaling Diuretic Response Is Impaired in Streptozotocin- Induced Diabetic Rats

title: Renal Afferent Signaling Diuretic Response Is Impaired in Streptozotocin- Induced Diabetic Rats abstract: Background. Renal insufficiency develops in diabetes and shows structural and functional abnormalities. Renal afferents, including chemoreceptors and mechanoreceptors located in the vascular and ureteropelvic portions of the kidney, may reflect changes in the environment and trigger an afferent nerve-mediated regulatory function that is known as the reno renal reflex. In this study, the involvement of these renal sensory receptors during the early diabetic state is defined. Methods. Diabetes was induced in rats after a tail vein injection of streptozotocin (STZ; 60 mg/kg intravenously). Four groups of rats, control (C), diabetic( DM), diabetic with acute insulin treatment (DMAI, 9 U/rat, subcutaneously, on the experimental day), and chronic insulin treatment (DMCI, 9 Ui rat, subcutaneously, daily) were studied. Spontaneous firing type 2-renal chemoreceptor( CR2), arterial mechanoreceptor (MRa), ureteropelvic mechanoreceptor (MRu), and venous mechanoreceptor (MRv) were identified by single-unit analysis of renal efferent nervous activity. The receptor activities were confirmed by their response patterns to stimuli elicited by renal arterial occlusion (RAO), backflow of urine, increasing arterial pressure, increasing ureteropelvic pressure (UP), or renal venous occlusion (RVO). The response of these afferent receptors to a challenge of volume expansion and their functional activities on renorenal reflexes were also examined. Immunostaining with PGP 9.5 was applied for examination of the nerve distribution in the diabetic kidney . The tissue level of histamine in the renal pelvis was determined. We explored the effect of histamine on renal receptor activity in these animals to address the possible role of histamine in MRu receptor activity. Results. In early diabetics, signaling activities in MRa and MRv were maintained; however, activity in CR2 and MRu was depressed. For CR2, the reduced basal discharge and the repressed responses to RAG, backflow of urine, and volume expansion found in DM rats were recovered by acute insulin treatment to restore glucose levels to near normal. For MRu, the depressed response to increasing UP and volume expansion was not restored by acute correction of hyperglycemia in DMAI rats. However, antihistamine treatment or chronic insulin treatment recovered the MRu response to mechanical stimuli in DM rats. Because of the desensitized CR2 and MRu activity , renorenal reflexes elicited by backflow of urine and increasing UP were depressed in DM rats. Conclusion. Despite a lack of structural changes, the operating system, signaling ability, and renorenal reflex regulatory function of two renal afferent nerve receptors, CR2 and MRu, are altered in the early diabetic state.

Bcl-Xl Augmentation Potentially Reduces Ischemia/Reperfusion Induced Proximal and Distal Tubular Apoptosis and Autophagy

title: Bcl-Xl Augmentation Potentially Reduces Ischemia/Reperfusion Induced Proximal and Distal Tubular Apoptosis and Autophagy abstract: Background. Apoptosis and autophagy may contribute to cell homeostasis in the kidney subjected to ischemia/reperfusion injury via mitochondrial injury. Ischemia/reperfusion induces differential sensitivity between proximal and distal tubules via a dissociated Bcl-xL expression. We hypothesized Bcl-xL augmentation in the proximal and distal tubules may potentially reduce ischemia/reperfusion induced renal dysfunction. Methods . We augmented Bcl-xL protein expression in the kidney with intrarenal adenoviral bcl-xL gene transfer and evaluated the potential effect of Bcl- xL augmentation on ischemia/reperfusion induced renal oxidative stress, apoptosis, and autophagy in the rat. Results. Intrarenal arterial Adv-bcl- xL administration augmented maximal Bcl-xL protein expression of rat kidney after 7 days of transfection. The primary location of Bcl-xL augmentation was found in proximal and distal tubules, but not in glomeruli. Ischemia/reperfusion increased mitochondrial cytochrome C release, renal O-2(-) level and renal 3-nitrosine and 4-hydroxyneonal accumulation, potentiated tubular apoptosis and autophagy, including increase in microtubule-associated protein 1 light chain 3 ( LC-3) and Beclin-1 expression, Bax/Bcl-xL ratio, caspase 3 expression and poly-(ADP- ribose)-polymerase fragments, and subsequent proximal and distal tubular apoptosis/autophagy. However, Adv-bcl-xL administration significantly reduced ischemia/reperfusion enhanced mitochondrial cytochrome C release, O-2(-) production, 3-nitrotyrosine and 4- hydroxynonenal accumulation, Beclin-1 expression, Bax/Bcl-YL ratio, and proximal and distal tubular apoptosis/autophagy, consequently improving renal dysfunction. Further study showed that Bcl-xL augmentation was more efficiently than Bcl-2 augmentation in amelioration of ischemia/reperfusion induced proximal and distal tubular apoptosis and renal dysfunction. Conclusions. Our results suggest that Adv-bcl- xL gene transfer significantly improves ischemia/ reperfusion -induced renal dysfunction via the downregulation of renal tubular apoptosis and autophagy.

Adenovirus-Mediated Bcl-2 Gene Transfer Inhibits Renal Ischemia/ Reperfusion Induced Tubular Oxidative Stress and Apoptosis

title: Adenovirus-Mediated Bcl-2 Gene Transfer Inhibits Renal Ischemia/ Reperfusion Induced Tubular Oxidative Stress and Apoptosis abstract: Ischemia/reperfusion induces oxidative injury to proximal and distal renal tubular cells. We hypothesize that Bcl-2 protein augmentation with adenovirus vector mediated bcl-2 ( Adv-bcl-2) gene transfer may improve ischemia/reperfusion induced renal proximal and distal tubular apoptosis through the mitochondrial control of Bax and cytochrome C translocation. Twenty-four hours of Adv-bcl-2 transfection to proximal and distal tubular cells in vitro upregulated Bcl-2/Bax ratio and inhibited hypoxia/ reoxygenation induced cytochrome C translocation, O2 production and tubular apoptosis. Intra-renal arterial Adv-bcl-2 administration with renal venous clamping augmented Bcl-2 protein of rat kidney in vivo in a time-dependent manner. The maximal Bcl-2 protein expression appeared at 7 days after Adv-bcl-2 administration and the primary location of Bcl-2 augmentation was in proximal and distal tubules, but not in glomeruli. With a real-time monitoring O2 production and apoptosis analysis of rat kidneys, ischemia/reperfusion increased renal O2 level, potentiated proapoptotic mechanisms, including decrease in Bcl-2/Bax ratio, increases in caspase 3 expression and poly-(ADP-ribose)-polymerase fragments and subsequent proximal and distal tubular apoptosis. However, Adv-bcl-2 administration significantly enhanced Bcl-2/Bax ratio, decreased ischemia/ reperfusion induced O2 amount, inhibited proximal and distal tubular apoptosis and improved renal function. Our results suggest that Adv-bcl-2 gene transfer significantly reduces ischemia/ reperfusion induced oxidative injury in the kidney.