Potent antitumor efficacy of XAF1 delivered by conditionally replicative adenovirus vector via caspase-independent apoptosis

XAF1 is a newly identified tumor-suppressor gene that can antagonize XIAP and sensitize cells to other cell death triggers. In this study, we utilized ZD55, a conditionally replicative adenovirus (CRAd) similar to ONYX-015 as the vector to transfer XAF1 into the tumor cells to evaluate its antitumor efficacy in vitro and in vivo. Potent and specific cytopathic effect (CPE) was observed upon infection with ZD55-XAF1 in tumor cell lines. Importantly, ZD55-XAF1 exhibited a superior suppression of tumor growth in an animal model of colorectal carcinoma in nude mice compared with Ad-XAF1 (E1-deleted replication-defective viral) and ONYX-015. Complete eradication of the established tumors was observed in four of eight mice. Our data also showed that infection with ZD55-XAF1 resulted in caspase-independent apoptosis. Although caspase-3, poly(ADP-ribose) polymerase were mildly activated in response to ZD55-XAF1 infection, pretreatment with pan-caspase inhibitor hardly influence its apoptosis-inducing activity. In summary, our study strongly suggested that ZD55-XAF1 could serve as an effective gene-virotherapy strategy and has highly potential against human cancers.

The effect of bi-level positive airway pressure mechanical ventilation on gas exchange during general anaesthesia

BACKGROUND

Atelectasis may occur and ventilation-perfusion mismatch may increase during general anaesthesia with neuromuscular paralysis and mechanical ventilation, though preservation of some intermittent muscle contraction might mitigate this process. There is still no ideal manoeuvre to minimize such mismatch or atelectasis. Bi-level positive airway pressure (BiPAP) ventilation adjusts to extra breaths and improves gas exchange during recovery of diaphragm function after neuromuscular paralysis. We hypothesize that BiPAP ventilation may limit the development of pulmonary shunt and may improve ventilation-perfusion mismatch when compared with standard IPPV, with or without PEEP when neuromuscular paralysis has been used during surgery.

METHODS

Twenty ventilated patients either on BiPAP or IPPV with or without PEEP were studied randomly using the multiple inert gas elimination technique (MIGET) at 60 and 120 min after rocuronium at induction and after 60 min. Non-invasive cardiac output (NICO) monitoring and plasma concentrations of rocuronium were measured. We compared the data of MIGET, gas exchange, haemodynamic variables and pulmonary mechanics measurements between the different ventilatory modes.

RESULTS

Intrapulmonary shunt (blood flow to V(A)/Q < 0.005) did not increase at 60 min of anaesthesia in any of the different ventilation modes compared with the shunt value before anaesthesia. Log standard deviation of perfusion increased in IPPV, with and without PEEP groups, compared with the baseline (P< 0.05) but did not increase in the BiPAP group. BiPAP ventilation generated a higher level of Pa(O2)than IPPV with or without PEEP (P<0.05).

CONCLUSION

BiPAP ventilation was beneficial in decreasing ventilation-perfusion mismatch and improving oxygenation when compared with conventional IPPV (with or without PEEP).

Hypoxia blocks 11beta-hydroxysteroid dehydrogenase type 2 induction in human trophoblast cells during differentiation by a time-dependent mechanism that involves both translation and transcription

The present study was undertaken to determine (1) if hypoxia-induced down-regulation of placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2; encoded by HSD11B2 gene) activity and protein in human trophoblast cells during in vitro differentiation was mediated at the level of HSD11B2 gene transcription; and (2) whether the reduced placental 11beta-HSD2 in pregnancies complicated with fetal growth restriction (FGR) was a consequence of intrinsic abnormalities in trophoblast cells. Trophoblast cells were isolated from uncomplicated pregnancies and those complicated with FGR at term, and cultured for up to 72 h under normoxic (20% oxygen) or hypoxic (1% oxygen) conditions. Under normoxia, 11beta-HSD2 activity and protein increased progressively over the 72 h culture period, which was accompanied by a corresponding rise in 11beta-HSD2 mRNA. As demonstrated previously, hypoxia blocked the increase in levels of both 11beta-HSD2 activity and protein within the first 24h. In contrast, although hypoxia also prevented the rise in 11beta-HSD2 mRNA, it did not do so until 48 h. This time-dependent effect of hypoxia on placental 11beta-HSD2 activity/protein and mRNA suggests a dual mechanism of action whereby hypoxia may induce a rapid down-regulation of 11beta-HSD2 protein synthesis, which occurs initially at the level of translation, and later extends to the level of transcription. Indeed, transient transfection studies demonstrated that hypoxia diminished HSD11B2 promoter activity. When trophoblast cells isolated from FGR placentas were cultured and allowed to differentiate under the same conditions, they not only exhibited a similar pattern of 11beta-HSD2 activity and mRNA expression but also responded to hypoxia similarly to those from normal placentas. This suggests that the reduced placental 11beta-HSD2 in FGR is not due to intrinsic abnormalities in trophoblast cells, but likely a result of extrinsic factors associated with FGR.

Sensitive detection of human papillomavirus in cervical, head/neck, and schistosomiasis-associated bladder malignancies

We assayed for the presence of human papilloma virus (HPV) DNA in serum and/or peripheral blood fraction (PBF) of individuals with cervical, head/neck, or bladder cancer due to schistosomiasis. Using mass spectroscopy coupled with competitive PCR, HPV DNA was detected at the individual molecule level by using "MassARRAY" assays. The resultant sensitivity was superior to real-time fluorescent PCR-based assays, while specificity was maintained. Our principal findings were: (i) Virtually all tested cervical cancers and schistosomiasis-associated bladder cancers, and a plurality of head/neck cancers, are associated with HPV DNA in the tumor. (ii) All 27 bladder cancers due to schistosomiasis were associated with the presence of HPV-16 DNA, which can be detected in tumor and serum but not in PBF. In contrast, no serum HPV-16 DNA signal was detected in seven individuals with schistosomiasis-associated bladder cancers after surgical removal of the tumor. (iii) Among the head/neck cancers we studied, anterior tumors were more often associated with HPV DNA in tumor, serum, and/or PBF than posterior tumors. (iv) In cervical cancer, where all tumors contain HPV DNA, viral DNA could be detected often in serum and/or PBF. Further, HPV-16 DNA was detected in serum and/or PBF of most patients with untreated high-grade cervical dysplasia but disappeared if the dysplasia was eliminated. The sensitive, specific, and quantitative MassARRAY technique should make it feasible to monitor cancer occurrence and treatment and recurrence of malignancies and dysplasias associated with HPV DNA.

Identification of two novel allelic variants of ESX1L in the human placenta: lack of an association with intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a leading cause of neonatal morbidity and mortality. Although epidemiological studies implicate an important role for genetic factors in determining birth weight, few candidate genes for IUGR have been identified. ESX1L, the orthologue of Esx1, is an X chromosome-linked human homeobox gene expressed in the placenta and testis. The present study was undertaken to determine if aberrations in the ESX1L gene were associated with idiopathic IUGR because targeted deletion of Esx1 in the mouse leads to abnormal placental development and consequent IUGR. Genotyping analysis of ESX1L gene was performed on placental samples from 22 normal term and 12 IUGR term fetuses. Two allelic variants were identified, and they contain an insertion and a deletion, respectively, of the same 27 nucleotides in the highly repetitive region of exon-4 that encodes the previously identified 12 contiguous repeats of a unique 9-amino acid motif, PPMAP(V/L)PPG. Thus, the insertion and deletion variants were predicted to code for an aberrant ESX1L protein containing 13 and 11 contiguous repeats, respectively. However, both variants were detectable and evenly distributed in normal as well as IUGR placentae, indicating that these two variants of ESX1L do not contribute to genetic susceptibility to idiopathic IUGR. Furthermore, no single nucleotide polymorphisms were identified, and there was no difference in the level of ESX1L mRNA between control and IUGR placentae. Taken together, these findings provide the first evidence that two allelic variants of ESX1L exist in the human placenta but they are not associated with idiopathic IUGR.