A quantitative multistandard reverse transcriptase-polymerase chain reaction assay of the cystic fibrosis transmembrane conductance regulator: its usefulness in studying efficiency of gene transfer

Development of a low-cost multi-channel nucleic acid detection PCR instrument and clinical detection application of COVID-19

Since the COVID-19 outbreak at the end of December 2019, a variety of novel Coronavirus nucleic acid detection methods have been proposed at home and abroad. Because of the disadvantages of most existing PCR instruments on the market such as long reaction time and high cost, this study developed a more timesaving and cheaper two-channel real-time quantitative PCR instrument. In this instrument, a PCR system combining a thermal cycle system and real-time fluorescence quantitative technology was designed. The software system and data processing, optical system, thermal cycle module, and hardware module of the PCR instrument were studied. The low-cost, portable real-time quantitative PCR system has been validated with consistent results compared to Bio-rad CFX Connect. At the same time, the same samples were used for the contract experiment with the hospital instrument, and the amplification result was better than the existing instrument in the hospital.

Current Status of Gene Therapy for Cystic Fibrosis Pulmonary Disease

Cystic fibrosis (CF) is a common lethal genetic disorder that affects all ethnic populations; however, it is most prevalent in Caucasians. Intensive basic research over the last 20 years has resulted in a wealth of information regarding the CF gene, its protein product and the mutational basis of disease. This increased understanding has lead to the development of gene therapy for the treatment of CF pulmonary disease. Delivery of the CF gene to the airway requires direct in vivo transfer using vectors encoding for normal CF transmembrane regulator (CFTR) protein. Several vectors are currently available for CF gene transfer and include both viral (adenoviruses, adeno-associated viruses) and non-viral (liposomal) systems. Initial clinical trials with each of these vectors have demonstrated that gene transfer to the CF airway is possible. The efficiency of transfer and duration of expression, however, have been limited. The effects of gene transfer on correction of the basic ion transport defects have also been highly variable and inconsistent, irrespective of the vector. Currently, the risk of severe immunological reactions is the primary factor limiting the clinical advancement of gene therapy. Both the adenoviral and liposomal vectors are associated with significant acute inflammatory reactions. The adenoviruses and adeno-associated viruses also elicit humoral immune responses that significantly reduce the efficiency of transgene expression and increase the risk of readministration. Several strategies are under investigation to improve the efficiency of gene transfer to the CF airway. These include overcoming local barriers in the lung, circumventing the immune response and improving vector internalization and/or uptake. Application of gene transfer in the child and possibly the fetus are also potential future clinical applications of gene therapy. However, despite considerable research with gene therapy, there is little evidence to suggest that a well tolerated and effective gene transfer method is imminent and aggressive use of conventional pharmacological therapies currently offer the greatest promise in the treatment of patients with CF.

Recombinant adenovirus vectors for gene therapy and clinical trials

In the last decade adenovirus (AdV) vectors have emerged as promising technology in gene therapy. They have been used for genetic modification of a variety of somatic cells in vitro and in vivo. They have been widely used as gene delivery vectors in experiments both with curative and preventive purposes. AdV vectors have been used in the experimental and in some extent in the clinical gene therapy of a variety of cancers. The combination of recombinant AdV technology with chemotherapy (pro drug system) seems to be promising, too. AdV vectors offer several advantages over other vectors. Replication defective vectors can be produced in very high titers (10(11) pfu/ml) thus allowing a substantially greater efficiency of direct gene transfer; they have the capacity to infect both replicating and nonreplicating (quiescent) cells from a variety of tissues and species. Several important limitations of adenovirus mediated gene transfer are also known, such as the relatively short-term (transient) expression of foreign genes, induction of the host humoral and cellular immune response to viral proteins and viral infected cells, which may substantially inhibit the effect of repeated treatment with AdV vectors, the limited cloning capacity and the lack of target cell specificity. However, the well-understood structure, molecular biology and host cell interactions of AdV-s offer some potential solutions to these limitations.

Effects of antiretroviral drug combinations on the differentiation of adipocytes

OBJECTIVE

Preadipocyte cell lines present a cell model with which to understand the physiopathological mechanisms underlying lipodystrophy syndrome, a common complication observed in patients treated with highly active antiretroviral therapy (HAART) that, in general, is associated with the use of protease inhibitors (PI) and nucleoside reverse transcriptase inhibitors (NRTI). The aim of this study was to evaluate the effects of NRTI and of PI and NRTI combinations in this cell model.

METHODS

The differentiation of 3T3-F442A cells was studied by monitoring the expression of specific genes in the presence of therapeutic concentrations of antiretroviral drugs. Messenger RNA (mRNA) was quantified by two reverse transcription-PCR-based methods.

RESULTS

In the presence of 2 microM saquinavir, 30 microM ritonavir or 1 microM zidovudine preadipocytes delayed their differentiation, whereas the use of 10 microM nelfinavir led to cell death. Indinavir (10 microM) promoted lipoprotein lipase expression whereas 1 microM lamivudine or 1 microM stavudine enhanced slightly the expression of the malic enzyme gene. However, the combination of indinavir, lamivudine and stavudine led to a large increase in both lipoprotein lipase and malic enzyme mRNA transcription whereas the combination of indinavir, lamivudine and zidovudine led to a 2.5-fold increase in the expression of the lipogenic malic enzyme gene. Similar potentiating effects of NRTI and PI were observed on the expression of the fatty acid synthase gene.

CONCLUSIONS

Our data suggest that, like PI (although to a lesser extent) NRTI interfere with the differentiation process of adipocytes. In addition, we demonstrate that the effects produced by combinations of NRTI and PI are different from those elicited by each drug separately. This point may be particularly relevant in understanding the physiopathological mechanisms underlying the lipodystrophic syndrome.