Suppressing PARylation by 2',5'-oligoadenylate synthetase 1 inhibits DNA damage-induced cell death.

High expression of 2',5'-oligoadenylate synthetase 1 (OAS1), which adds AMP residues in 2',5' linkage to a variety of substrates, is observed in many cancers as a part of the interferon-related DNA damage resistance signature (IRDS). Poly(ADP-ribose) (PAR) is rapidly synthesized from NAD+ at sites of DNA damage to facilitate repair, but excessive PAR synthesis due to extensive DNA damage results in cell death by energy depletion and/or activation of PAR-dependent programmed cell death pathways. We find that OAS1 adds AMP residues in 2',5' linkage to PAR, inhibiting its synthesis in vitro and reducing its accumulation in cells. Increased OAS1 expression substantially improves cell viability following DNA-damaging treatments that stimulate PAR synthesis during DNA repair. We conclude that high expression of OAS1 in cancer cells promotes their ability to survive DNA damage by attenuating PAR synthesis and thus preventing cell death.

Initial Riociguat Monotherapy and Transition from Sildenafil to Riociguat in Patients with Idiopathic Pulmonary Arterial Hypertension: Influence on Right Heart Remodeling and Right Ventricular-Pulmonary Arterial Coupling.

PURPOSE: To evaluate the influence of riociguat on World Health Organization functional class (WHO FC), 6-min walk distance (6MWD), right heart remodeling, and right ventricular-pulmonary arterial (RV-PA) coupling in patients with idiopathic pulmonary arterial hypertension (IPAH) who are treatment-naïve or who have failed to achieve treatment goals with sildenafil therapy. METHODS: Twenty patients with IPAH were enrolled: 12 had not previously received PAH-targeted therapy (treatment-naïve subgroup) and 8 had been receiving sildenafil therapy but failed to achieve treatment goals; on entering this pilot study these 8 patients were switched from sildenafil to riociguat therapy (treatment-switch subgroup). Patients received riociguat individually dose-adjusted up to a maximum of 2.5 mg three times daily. After 12 weeks, patients were assessed for WHO FC, 6MWD, right heart remodeling, and RV-PA coupling. RESULTS: Riociguat significantly improved WHO FC in treatment-naïve patients (from 0/4/8/0 patients in WHO I/II/III/IV at baseline to 1/6/5/0 at week 12) and in treatment-switch patients (from 0/4/4/0 patients in WHO I/II/III/IV at baseline to 1/4/3/0 at week 12). Additionally, treatment-naïve and treatment-switch patients showed significant improvements at week 12 versus baseline in 6MWD (increases of + 76.8 m and + 71.6 m, respectively), RV systolic function, and RV-PA coupling. CONCLUSION: These results support the proven efficacy of riociguat in patients with IPAH, including treatment-naïve patients and those switching to riociguat following failure to achieve treatment goals with sildenafil, and suggest that it may be possible to delay disease progression in this patient group.

Results of orchiopexy for the undescended testis.

The undescended testis is one of the most common congenital abnormalities of the genitourinary system. Outcomes of orchiopexy include (1) having a viable, palpable testis in the scrotum, (2) fertility, as measured by paternity rates or semen analysis in adulthood and (3) risk of testicular cancer. Multiple operative techniques have been described and are associated with various success rates. In the past decade, success of orchiopexy for inguinal testes has been >95%. For abdominal testes, success for orchiopexy has been >85-90% in most series with single stage orchiopexy or two stage Fowler-Stephens orchiopexy, both with open surgical or laparoscopic technique. However, having a palpable testis in the scrotum does not assure fertility, as there are iatrogenic factors that may adversely affect the outcome. In adult men with a history of unilateral orchiopexy, fertility is nearly normal, but is significantly reduced following bilateral orchiopexy. The risk of testicular carcinoma is increased by a factor of 3.7 to 7.5 times. Tumor type is most commonly seminoma if the testis is undescended, whereas tumors that occur following orchiopexy are much more likely to be nonseminomatous.

High resolution NMR analysis of the seven transmembrane domains of a heptahelical receptor in organic-aqueous medium.

The NMR properties of seven peptides representing the transmembrane domains of the alpha-factor receptor from Saccharomyces cerevisiae were examined in trifluoroethanol/water (4:1) at 10 to 55 degrees C. The parameters extracted indicated all peptides were helical in this membrane mimetic solvent. Using chemical shift indices as the criterion, helicity varied from 64 to 83%. The helical residues in the peptides corresponded to the region predicted to cross the hydrocarbon interior of the bilayer. A study of a truncated 25-residue peptide corresponding to domain 2 gave evidence that the helix extended all the way to the N-terminus of this peptide, indicating that sequence and not chain end effects are very important in helix termination for our model peptides. Both nuclear Overhauser effect spectroscopy (NOESY) connectivities and chemical shift indices revealed significant perturbations around prolyl residues in the helices formed by transmembrane domains 6 and 7. Molecular models of the transmembrane domains indicate that helices for domains 6 and 7 are severely kinked at these prolyl residues. The helix perturbation around proline 258 in transmembrane domain 6 correlates with mutations that cause phenotypic changes in this receptor.