A review on current status of antiviral siRNA

Viral diseases like influenza, AIDS, hepatitis, and Ebola cause severe epidemics worldwide. Along with their resistant strains, new pathogenic viruses continue to be discovered so creating an ongoing need for new antiviral treatments. RNA interference is a cellular gene‐silencing phenomenon in which sequence‐specific degradation of target mRNA is achieved by means of complementary short interfering RNA (siRNA) molecules. Short interfering RNA technology affords a potential tractable strategy to combat viral pathogenesis because siRNAs are specific, easy to design, and can be directed against multiple strains of a virus by targeting their conserved gene regions. In this review, we briefly summarize the current status of siRNA therapy for representative examples from different virus families. In addition, other aspects like their design, delivery, medical significance, bioinformatics resources, and limitations are also discussed.     

Rapidly Progressive Congenital Rhabdomyosarcoma Presenting with Multiple Cutaneous Lesions: An Uncommon Diagnosis and a Therapeutic Challenge

Congenital rhabdomyosarcomas (RMSs) are rare tumors with variable clinical presentations. A 2 month-old, term male neonate (37 weeks, 4 days), weighing 3.2 kg, born to a 24 year-old primigravida, by simple vaginal delivery presented with multiple erythematous papulonodular lesions over his trunk that progressed to his whole body, on the first day of delivery. Prior to conception, his mother was treated for polycystic ovarian disease. On the tenth day, his chest computed tomogram scans revealed multiple, heterogeneously enhancing, bilateral pleural-based soft tissue density nodular lesions, along with multiple soft tissue density lesions, involving skeletal muscles of all his body parts. Microsections from two biopsies (on 10th day and after 2 months) revealed a malignant round cell tumor with cells arranged in a diffuse, solid pattern, comprising embryonal and solid alveolar components. Immunohistochemically, the tumor cells were diffusely positive for desmin, myoD1 and myogenin. Diagnosis of embryonal and alveolar (mixed type) RMS was offered. Further molecular cytogenetic analysis was negative for PAX3-FKHR and PAX7-FKHR. The patient was induced on chemotherapy as per intergroup rhabdomyosarcoma study IV protocol. There was treatment response with near total remission after 8 weeks of treatment. Thereafter, new lesions started appearing that also disappeared after modification of the chemotherapy drugs. However, after 16 months, the baby died of brain metastasis. The present case forms the fourth case report of an aggressive form of a congenital RMS with extensive cutaneous involvement and brain metastasis. A review of previously diagnosed cases of congenital RMSs is discussed herewith.     

Role of HPV DNA testing in predicting cervical intraepithelial lesions: comparison of HC HPV and ISH HPV

Human papillomavirus (HPV) is widely accepted as the primary agent involved in the development of squamous intraepithelial neoplasia and cervical carcinoma. Several commercial tests are available for detecting HPV DNA. This study compares the efficacy of INFORM HPV (in situ hybridization [ISH] HPV) and HCII (HC HPV) in predicting cervical lesions. A total of 762 sequential Papanicolaou (Pap) smears determined by cytologic examination to be either atypical squamous cells of undetermined significance (ASC-US) or low-grade squamous intraepithelial lesions (LSIL) were tested by both Hybrid Capture (HC) HPV and ISH HPV; 250 follow-up biopsies were reviewed as the reference standard for presence or absence of a lesion. ISH HPV and HC HPV differed significantly in accurately predicting biopsy findings from ASC-US and LSIL cases. The overall sensitivity and specificity of ISH HPV were 97% (28/29) and 86% (191/221); and HC HPV was 79% (23/29) and 56% (123/221). The positive predictive value (PPV) of ISH HPV was 48% (28/58) vs HC HPV value of 19% (23/121). Negative predictive value (NPV) was also better with ISH HPV at 99% (191/192) and HC HPV at 95% (123/129). Of equal importance, ISH HPV demonstrated a lower false-positive rate compared to HC HPV, 12% (30/250) vs 39% (98/250), as well as having a slightly lower false-negative rate 0.4% (1/250) vs 2.4% (6/250). ISH HPV is more predictive of biopsy histopathology in patients with detectable cervical lesions than is HC HPV. Effective triage of patients by HPV analysis using ISH HPV as compared to HC HPV has the potential of significant public health impact by reducing unnecessary colposcopies, as well as adverse medical, social, and psychological patient consequences.     

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.