Genomic Signature of Mismatch Repair Deficiency in Areca Nut-Related Oral Cancer

Areca nut (AN) chewing contributes to an increase of oral squamous cell carcinoma (OSCC) cases in South and Southeast Asia; however, genomic events underlying the carcinogenesis process of AN-related OSCC remain unclear. Here, we comprehensively describe the genomic and transcriptome alterations of 113 Chinese OSCC patients (89 AN related and 24 AN negative) by whole-exome sequencing and RNA sequencing, and we compared the genomic differences between AN-related and AN-negative samples by integrating sequencing data of 325 OSCC patients from The Cancer Genome Atlas database and 50 from a published Taiwanese study. We identified 11 significantly mutated genes for OSCC, including 4 novel ones (ATG2A, WEE1, DST, and TSC2), of which WEE1 and ATG2A mutated with significantly higher rates in AN-related samples (P = 0.04 and P = 0.003, respectively). Mutational signature analysis revealed that AN-related OSCCs were specially characterized by the genomic signature of mismatch repair deficiency (dMMR), which could also predict the prognosis status of AN-related OSCC. In addition, an elevated PD-L1 expression was also observed in both AN-related patients (P = 3.71 × 10^-11) and those with a high dMMR level (P = 1.99 × 10^-4). Further differential expression analysis and in vitro experiments confirmed the role of dMMR in the development of OSCC induced by AN exposure. Taken together, this study first revealed the molecular profiles and highlighted the role of dMMR in AN-related OSCC among the Chinese population and identified that AN-related OSCC may represent a potential cohort for effective anti-PD-1/L1 immunotherapy.

Neutron yield enhancement in laser-induced deuterium-deuterium fusion using a novel shaped target

Neutron yields have direct correlation with the energy of incident deuterons in experiments of laser deuterated target interaction [Roth et al., Phys. Rev. Lett. 110, 044802 (2013) and Higginson et al., Phys. Plasmas 18, 100703 (2011)], while deuterated plasma density is also an important parameter. Experiments at the Shenguang II laser facility have produced neutrons with energy of 2.45 MeV using d (d, n) He reaction. Deuterated foil target and K-shaped target were employed to study the influence of plasma density on neutron yields. Neutron yield generated by K-shaped target (nearly 10(6)) was two times higher than by foil target because the K-shaped target results in higher density plasma. Interferometry and multi hydro-dynamics simulation confirmed the importance of plasma density for enhancement of neutron yields.

Spectrally peaked electron beams produced via surface guiding and acceleration in femtosecond laser-solid interactions

Highly collimated MeV electron beam guiding has been observed along the target surface following the interaction of bulk target irradiation by femtosecond laser pulses at relativistic intensities. The beam quality is shown to depend critically on the laser contrast: With a ns prepulse, the generated electron beam is well concentrated and intense, while a high laser contrast produces divergent electron beams. In the case of large preplasma scale lengths, tunable guiding and acceleration of the target surface electrons is achieved by changing the laser incident angle. By expanding the preplasma scale length to several hundred micrometers, we obtained MeV spectrum-peaked electron beams with a 100 pC per laser pulse and divergence angles of only 3°. This technique suggests a stable method of injection of elections into a variety of accelerator designs.

Intraurethral brachytherapy for prevention of recurrent urethral stricture after internal urethrotomy or transurethral resection of scar

BACKGROUND PURPOSE

Restricture after internal urethrotomy is the major limitation to the long-term success of the procedure. The objective of this study was to evaluate the effect of intraurethral brachytherapy after internal urethrotomy or transurethral scar resection on recurrent urethral stricture.

PATIENTS AND METHODS

From January 1998 to June 1999, catheter-based intraurethral brachytherapy with 192-iridium was performed in 17 patients with recurrent urethral stricture to prevent restricture after internal urethrotomy or transurethral resection of scar. The radiation was repeated within 3 days after surgery to reach a total dosage of 1000 to 1500 cGy.

RESULTS

During the follow-up (range 14-27 months; mean 20 months), two patients had dysuria, including one patient with an atonic detrusor muscle. The other patient needed self-dilation. Fifteen patients presented normal voiding. The stricture recurred 3 months later in only one patient, so the restricture rate is 7%. No significant complication was observed associated with brachytherapy during the follow-up.

CONCLUSION

Intraurethral brachytherapy after internal urethrotomy or transurethral resection of scar is a safe and effective treatment for recurrent urethral strictures.