MAL31, a sugar transporter involved in pullulan biosynthesis in Aureobasidium pullulans.

To investigate the role of the sugar transporter MAL31 on pullulan biosynthesis, the coding gene mal31 was respectively disrupted and overexpressed in the parental strain A. pullulans CCTCC M 2012259 to construct mutants of A. pullulans Δmal31 and A. pullulans Mal31. Batch pullulan production significantly decreased by 69.1 % in A. pullulans Δmal31 but increased by 15.9 % in A. pullulans Mal31, as compared to the parental strain. We performed kinetics analysis, assays of key enzymes, determination of intracellular UDPG, NADH, and ATP contents, and measurement of transcriptional levels of genes associated with pullulan biosynthesis and excretion. The results confirmed that the mal31 disruption decreased the glucose consumption rate, decreased the formation rate and titer of pullulan, but increased the intracellular UDPG supply for ß-glucan accumulation. In contrast, the mal31 overexpression increased the transcriptional levels of genes associated with pullulan biosynthesis, and accelerated the rates of glucose consumption and pullulan formation, thereby increased pullulan production. Our findings revealed that MAL31 is involved in the transport of precursors for pullulan biosynthesis. This study provides an accurate operating site for genetic modification of A. pullulans for improving pullulan production and also presents a feasible technique route for the overproduction of other polysaccharides.

Evaluation of MRI-TRUS fusion versus cognitive registration accuracy for MRI-targeted, TRUS-guided prostate biopsy.

OBJECTIVE: The purpose of this article is to compare transrectal ultrasound (TRUS) biopsy accuracies of operators with different levels of prostate MRI experience using cognitive registration versus MRI-TRUS fusion to assess the preferred method of TRUS prostate biopsy for MRI-identified lesions. SUBJECTS AND METHODS; One hundred patients from a prospective prostate MRI-TRUS fusion biopsy study were reviewed to identify all patients with clinically significant prostate adenocarcinoma (PCA) detected on MRI-targeted biopsy. Twenty-five PCA tumors were incorporated into a validated TRUS prostate biopsy simulator. Three prostate biopsy experts, each with different levels of experience in prostate MRI and MRI-TRUS fusion biopsy, performed a total of 225 simulated targeted biopsies on the MRI lesions as well as regional biopsy targets. Simulated biopsies performed using cognitive registration with 2D TRUS and 3D TRUS were compared with biopsies performed under MRI-TRUS fusion. RESULTS: Two-dimensional and 3D TRUS sampled only 48% and 45% of clinically significant PCA MRI lesions, respectively, compared with 100% with MRI-TRUS fusion. Lesion sampling accuracy did not statistically significantly vary according to operator experience or tumor volume. MRI-TRUS fusion-naïve operators showed consistent errors in targeting of the apex, midgland, and anterior targets, suggesting that there is biased error in cognitive registration. The MRI-TRUS fusion expert correctly targeted the prostate apex; however, his midgland and anterior mistargeting was similar to that of the less-experienced operators. CONCLUSION: MRI-targeted TRUS-guided prostate biopsy using cognitive registration appears to be inferior to MRI-TRUS fusion, with fewer than 50% of clinically significant PCA lesions successfully sampled. No statistically significant difference in biopsy accuracy was seen according to operator experience with prostate MRI or MRI-TRUS fusion.

Fabrication of doxorubicin functionalized gold nanorod probes for combined cancer imaging and drug delivery.

A novel strategy was utilized to develop a stable probe based on thiolated poly(ethylene glycol) (SH-PEG) and polyacrylic acid (PAA) functionalized gold nanorods (GNRs), following the attachment of an anti-cancer drug, doxorubicin (DOX), to obtain PAA-PEG-GNRs@DOX assemblies. Importantly, the obtained probe as a novel drug-delivery and fluorescent imaging agent for simultaneous imaging of and drug delivery to prostate cancer cells has also been demonstrated. In addition to designing PAA-PEG-GNRs that passively target tumor cells for cancer-fighting drug therapy, GNRs are also regarded as hyperthermia agents for photokilling cancer cells, so that the tumor would be attacked on two fronts simultaneously.