Dendritic Cell-Derived Exosomes Stimulate Stronger CD8^＋ CTL Responses and Antitumor Immunity than Tumor Cell-Derived Exosomes

Exosomes （EXO） derived from dendritic cells （DC） and tumor cells have been used to stimulate antitumor immune responses in animal models and in clinical trials. However, there has been no side-by-side comparison of the stimulatory efficiency of the antitumor immune responses induced by these two commonly used EXO vaccines. In this study, we selected to study the phenotype characteristics of EXO derived from a transfected EG7 tumor cells expressing ovalbumin （OVA） and OVA-pulsed DC by flow cytometry. We compared the stimulatory effect in induction of OVA-specific immune responses between these two types of EXO. We found that OVA protein-pulsed DCOVA-derived EXO （EXODC） can more efficiently stimulate naive OVA-specific CD8^＋ T cell proliferation and differentiation into cytotoxic T lymphocytes in vivo, and induce more efficient antitumor immunity than EG7 tumor cell-derived EXO （EXOEG7）. In addition, we elucidated the important role of the host DC in EXO vaccines that the stimulatory effect of EXO is delivered to T cell responses by the host DC. Therefore, DC-derived EXO may represent a more effective EXO-based vaccine in induction of antitumor immunity. Cellular ＆ Molecular Immunology. 2006;3（3）：205-211.     

Preclosure Pressure Gradients Predict Patent Ductus Arteriosus Patients at Risk for Later Left Pulmonary Artery Stenosis

The objective of this study was to evaluate the incidence of pre-existing catheterization left pulmonary artery (LPA) gradients and correlation of these gradients with later LPA stenosis after successful patent ductus arteriosus (PDA) occlusion. We performed a single-center review of 130 patients with PDA closure from October 1993 to February 2005. We analyzed the pre-PDA closure LPA pressure gradients at catheterization to determine if these were predictive of late LPA stenosis. On follow-up, a V _max >2 m/s by echocardiogram (transthoracic echocardiography; TTE) was considered indicative of possible LPA stenosis. Left lung perfusion of <35% was considered diagnostic of significant LPA stenosis. Post PDA closure, possible LPA stenosis by TTE was seen in 8 of 128 patients (6.25%). Seven of these eight had precatheter LPA gradients >7 mm Hg. Five of these had perfusion scans, three of the five had significant LPA stenosis, and two underwent LPA angioplasty. Patients with LPA catheter gradients >7 mm Hg were more likely to have possible LPA stenosis by TTE, significant LPA stenosis by lung scan, and intervention with LPA angioplasty. In conclusion, a preclosure main pulmonary artery-to-LPA pressure gradient >7 mm Hg was found in all patients who developed significant LPA stenosis on follow-up after transcatheter PDA closure. It appears likely that these patients have LPA abnormality rather than stenosis caused by the PDA occlusion device. Patients with preclosure LPA gradients >7 mm Hg should undergo follow-up evaluations for detection of significant stenosis and may require treatment if an important flow abnormality is documented.     

Augmenting Regional Cerebral Blood Flow Using External-to-Internal Carotid Artery Flow Diversion Method

The objective of this study was to assess the effect of flow diversion by external carotid artery (ECA) occlusion on ipsilateral regional cerebral blood flow (rCBF). Local cerebral hyperperfusion in rats (n = 12) was induced by ligating the right ECA. Ipsilateral rCBF was determined pre- and post-ligation for 120 min using a laser Doppler flow meter. Sham animals (n = 6) were subjected to the craniotomy without ligation of the right ECA. In a separate series of rats (n = 5), brain tissue oxygen levels (pO₂) in the right and left brain hemispheres were determined before and 90 min after ligation of the right ECA using a tissue oxygenation monitoring unit. We investigated the effect of ECA occlusion hemispheric changes in rCBF in one clinical case as a proof of concept. Ligation of ECA resulted in a statistically significant increase in rCBF on the ipsilateral side compared to the sham-operated rats (p < 0.0001). On average we observed a 34% increase (95% CI: 24–45%) in rCBF in the ipsilateral territory in the treated group compared with sham-operated rats. There was no significant variation in MAP for the treated animals. Vascular permeability and cerebral water content in the right hemisphere after ligation of ECA did not significantly differ from the contralateral hemisphere. Ipsilateral hemisphere tissue pO₂ was significantly higher compared to the contralateral area (p < 0.002) post-ligation or to the ipsilateral area (p < 0.001) prior to ligation. In the clinical case, occlusion of ECA resulted in 3.6% and 12.1% increase in peak value and rise-time of the time-density curves. Flow diversion by temporary occlusion of the ECA can result in increased rCBF and cerebral pO₂ on the ipsilateral side. The strategy may represent a viable option to augment rCBF in focal cerebral ischemia.     

Germline mutations in RAD51, RAD51AP1, RAD51B, RAD51C,RAD51D, RAD52 and RAD54L do not contribute to familial chronic lymphocytic leukemia.

While familial predisposition to B-cell chronic lymphocytic leukemia (CLL) is well recognized no gene which when mutated in the germline has been unambiguously shown to confer susceptibility to the disease. An approach based on mutation screening methods targeted to coding regions of candidate genes offers an attractive strategy for the identification of rare disease-causing alleles. The RAD genes participate in the cellular response to DNA double strand breaks, detecting DNA damage, activating cell cycle checkpoints and apoptosis. Defects in members of these genes are linked to increased chromosomal instability and in lymphoma predisposition, thereby representing strong candidate susceptibility genes a priori. To examine this proposition we screened 75 familial CLL probands for germline mutations in this set of genes. No overt pathogenic mutations were identified. These findings indicate that germline mutations in RAD51, RAD51AP1, RAD51L1, RAD51L3, RAD52 and RAD54L are unlikely to be causal of an inherited predisposition to CLL.     

Combining radioimmunotherapy with antihypoxia therapy 2-deoxy-D-glucose results in reduction of therapeutic efficacy.

PURPOSE: The efficacy of solid tumor radioimmunotherapy is reduced by heterogeneous tumor distribution of the radionuclide, with dose mainly deposited in the normoxic region and by the relative radioresistance of hypoxic tumor cells. In an attempt to overcome these challenges, radioimmunotherapy was combined with 2-deoxy-d-glucose (2DG), a hypoxia-selective cytotoxic inhibitor of glucose metabolism. EXPERIMENTAL DESIGN: In vitro toxicity of 2DG in LS174T cultures was tested using a colony-forming assay. The effect of combining 2DG with radioimmunotherapy in vivo was tested by administering radiolabeled anti-carcinoembryonic antigen antibody ([(131)I]A5B7 IgG1 whole monoclonal) to nude mice bearing s.c. LS174T tumors, followed by 10 daily injections of 2DG (2.0 g/kg). Tumors were measured to assess therapeutic efficacy. RESULTS: Data from in vitro studies confirmed 2DG cytotoxicity in this cell line. Greater toxicity was observed under standard laboratory conditions and in hypoxic cultures than at intermediate, physiologically relevant levels of glucose and oxygen. Alone, 2DG had no effect on in vivo tumor growth (P = 0.377 compared with saline-treated controls). Combination of radioimmunotherapy with 2DG reduced the therapeutic effect of radioimmunotherapy (e.g., 150 microCi (131)I alone mean survival time, 48.33 +/- 16.83 days; combined with 2DG, 30.67 +/- 5.62 days, P = 0.038). CONCLUSIONS: The combination investigated had a detrimental effect on survival. It is suggested that a cellular metabolic response to more aggressive therapy, previously reported in vitro, caused this. The results of this study have implications for the clinical application of combined cancer therapies with an antimetabolic modality component.     

Microdistribution of targeted, fluorescently labeled anti-carcinoembryonic antigen antibody in metastatic colorectal cancer: implications for radioimmunotherapy.

PURPOSE: Most radioimmunotherapy studies on radiolabeled antibody distribution are based on autoradiographic and radioluminographic data, which provide a lack of detailed information due to low resolution. We used fluorescently labeled anti-carcinoembryonic antigen (CEA) antibody (A5B7) to investigate quantitatively the kinetics and microdistribution of antibody in a clinically relevant orthotopic colorectal cancer model (LS174T) using high-resolution digital microscopy. EXPERIMENTAL DESIGN: Nude mice bearing LS174T liver orthotopic tumors received a single i.v. injection of fluorescently labeled A5B7 and were sacrificed at 10 minutes, 1 hour, or 24 hours postinjection. Before sacrifice, mice were injected with the perfusion marker Hoechst 33342. An anti-CD31 antibody was used to detect blood vessel distribution. Cryostat sections were processed with immunofluorescence procedures and analyzed with fluorescence microscopy and image analysis techniques. The fluorescence images were related to morphologic images of the same or adjacent tumor sections. RESULTS: Fluorescently labeled antibody showed rapid, selective uptake into tumor deposits, with a strong negative correlation with tumor size at 10 minutes and 1 hour (P < or = 0.01). By 24 hours, the correlation was no longer significant. The study showed movement of antibody across the tumor with time and a tendency to localize more uniformly by later time points (24 hours). The rate of antibody motility was similar in small and large tumor metastases, but small deposits showed more rapid antibody localization. Intratumoral vessels were positively related to tumor size (P < or = 0.001). CONCLUSION: The obtained data suggest that radioimmunotherapy can be highly efficient in an adjuvant or minimal residual disease setting.     

Utility of restriction fragment analysis for typing herpes simplex virus amplicons following PCR of targets in the DNA polymerase gene

We compared the utility of restriction endonuclease cleavage to type herpes simplex virus DNA polymerase gene amplicons from two well established PCR primer sets. Amplicons typed using Ava II had a 96% correlation to type determined by monoclonal antibody staining, while amplicons typed using Drd I had a 72% correlation to type determined by monoclonal antibody staining.     

Intestinal obstruction caused by malrotation of the gut in atrial isomerism.

Five children with atrial isomerism developed intestinal obstruction caused by malrotation of the gut. Other than asplenia, the extracardiac anomalies in these syndromes are rarely regarded as important as the outcome after intestinal surgery is poor. As cardiac treatment improves, early investigation and intervention for intestinal symptoms becomes more important.