Novel use of riociguat in infants with severe pulmonary arterial hypertension unable to wean from inhaled nitric oxide.

Introduction: Riociguat, an oral soluble guanylate cyclase stimulator, has been approved for use in adults with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension. However, there is limited data on its therapeutic use in children. Case Presentation: We report the case of two infants with severe suprasystemic pulmonary hypertension who were successfully treated with riociguat after failure to wean off inhaled nitric oxide (iNO) despite combination PAH therapy. Case 1 is a 6-month-old term male with TBX4 deletion who presented with severe hypoxemic respiratory failure and severe PAH immediately after birth. Initial cardiac catheterization showed PVRi 15.5 WU*m2. Marked hypoxemia and PAH persisted despite aggressive therapy with sildenafil, bosentan, intravenous treprostinil, and milrinone. The infant required high doses of inhaled nitric oxide (60 ppm) and manifested significant post-ductal hypoxemia and hemodynamic instability with any attempt at weaning. After discontinuation of sildenafil, initiation, and very slow uptitration of riociguat, the patient was able to maintain hemodynamic stability and wean from nitric oxide over 6 weeks with persistently severe but not worsened pulmonary hypertension. Case 2 is a 4-month-old term male with compound heterozygous SLC25A26 mutation and severe pulmonary hypertension. Initial cardiac catheterization showed PVRi 28.2 WU*m2. After uptitration of sildenafil, bosentan, and IV treprostinil, serial echocardiograms continued to demonstrate near-systemic pulmonary hypertension. He failed multiple attempts to wean off typical doses of iNO (10-20 ppm) over the following weeks with tachypnea, hypoxemia, and worsening pulmonary hypertension on echocardiogram despite continued aggressive combination targeted therapy. After a 24-h sildenafil washout, he was initiated and uptitrated on riociguat with concomitant, successful wean of nitric oxide over one week that was well tolerated. No serious adverse effects in the titration period were observed. Conclusion: Riociguat may be considered as an adjuvant therapeutic agent in selected children with severe PAH who are poorly responsive to sildenafil therapy and unable to wean from iNO.

Villin-type headpiece domains show a wide range of F-actin-binding affinities.

The villin-type "headpiece" domain is a modular motif found at the extreme C-terminus of larger "core" domains in over 25 cytoskeletal proteins in plants and animals. Although headpiece is classified as an F-actin-binding domain, it has been suggested that some expressed fusion-proteins containing headpiece may lack F-actin-binding in vivo. To determine the intrinsic F-actin affinity of headpiece domains, we quantified the F-actin affinity of seven headpiece domains and three N-terminal truncations, under identical in vitro conditions. The constructs are folded and adopt the native headpiece structure. However, they show a wide range of affinities that can be grouped into high, low, and nonspecific-binding categories. Computer models of the structure and charged surface potential of these headpiece domains suggest features important for high F-actin affinity. We conclude that not all headpiece domains are intrinsically F-actin-binding motifs, and suggest that the surface charge distribution may be an important element for F-actin recognition.

NMR structure of an F-actin-binding "headpiece" motif from villin.

A growing family of F-actin-bundling proteins harbors a modular F-actin-binding headpiece domain at the C terminus. Headpiece provides one of the two F-actin-binding sites essential for filament bundling. Here, we report the first structure of a functional headpiece domain. The NMR structure of chicken villin headpiece (HP67) reveals two subdomains that share a tightly packed hydrophobic core. The N-terminal subdomain contains bends, turns, and a four-residue alpha-helix as well as a buried histidine residue that imparts a pH-dependent folding. The C-terminal subdomain is composed of three alpha-helices and its folding is pH-independent. Two residues previously implicated in F-actin-binding form a buried salt-bridge between the N and C-terminal subdomains. The rest of the identified actin-binding residues are solvent-exposed and map onto a unique F-actin-binding surface.

Experience with intubated patients does not affect the accidental extubation rate in pediatric intensive care units and intensive care nurseries.

Accidental extubation is a potentially serious event for pediatric or neonatal patients with respiratory failure, especially in clinical settings in which personnel capable of performing reintubation may not be readily available. Thus the rate of accidental extubation in small intensive care units that operate without 24-hour in-house physician availability may be an important quality assurance indicator. The objective of this study were to determine the accidental extubation rate at a single small pediatric intensive care unit (PICU) and compare it with published reports. This study was carried out in a six-bed PICU at Washoe Medical Center in Reno, Nevada, with a relatively low level of patient acuity, as measured by PRISM score and the frequency of intubation, and without 24-hour in-house physician availability. All intubated patients admitted during the 5-year period from January 1, 1989 to December 31, 1993 were included. The primary outcome measure was the occurrence of accidental extubation. We observed only two accidental extubations in 1,749 intubated-patient-days (IPD) (0.114 accidental extubations/100 IPD [95% confidence interval 0.014-0.413 accidental extubations/ 100 IPD]). This rate of accidental extubation was compared with data in published reports from neonatal intensive care units (NICUs) and PICUs, which ranged from 0.14 accidental extubations/100 IPD to 4.36 accidental extubations/100 IPD. The dependence of the observed accidental extubation rate on unit size and institutional experience with intubated patients, as measured by the average number of intubated patients, was examined. We found no evidence that the accidental extubation rate is higher in smaller units or units with less institutional experience. Low rates can be achieved in small units with low acuity.

Differential response of cervical intraepithelial and cervical carcinoma cell lines to transforming growth factor-beta 1.

Transforming growth factor-beta 1 (TGF-beta 1) is a potent inhibitor of epithelial cell proliferation. It has been proposed that loss of sensitivity to growth inhibition by TGF-beta 1 may be an important step in the development of cervical carcinoma, but it remains unclear whether this represents an early or a late event. We compared the sensitivity to TGF-beta 1 of nontumorigenic human papillomavirus deoxyribonucleic acid (HPV DNA)-positive cell lines derived from cervical intraepithelial neoplasia (CIN), of newly established cervical carcinoma cell lines, of nontumorigenic HPV DNA-transfected cervical cell lines, and of normal ectocervical cells. There is a dose-dependent inhibition of DNA synthesis by TGF-beta 1 in the CIN cell lines and the HPV DNA-transfected cell lines. The carcinoma cell lines are resistant to the growth inhibitory effects of TGF-beta 1. The CIN cell lines are significantly more sensitive than the carcinoma cell lines (P < 0.001), but significantly less sensitive than normal cervical cells (P < 0.05). A CIN cell line which contains HPV 31b DNA is more sensitive to TGF-beta 1 at early passage than at late passage (P < 0.05). There are no differences in the sensitivity to the growth inhibitory effects of TGF-beta 1 between subclones of this cell line that have different episomal HPV DNA content, population-doubling time, or differentiation characteristics. Both normal and abnormal cervical epithelial cells were able to secrete latent TGF-beta 1 or TGF-beta 2. We conclude that resistance to growth inhibition by TGF-beta 1 is likely to be a late event in the development of cervical carcinoma; it is not the mere consequence of immortalization by HPV genes acquired following transfection in vitro or infection in vivo.

Quantitative quality assurance in a community hospital pediatric intensive care unit.

Unbiased, objective evaluations of quality of care are preferred over subjective evaluations. We observed 681 admissions to a pediatric intensive care unit of a community hospital from 1989 through 1990 for outcomes and physiologic profiles of the patients on the admission day using the Pediatric Risk of Mortality score to assess severity of illness. Mortality adjusted for severity of illness was compared with that predicted from a pediatric intensive care unit of a tertiary medical center: 32.6 deaths were predicted based on the physiologic profiles, and 23 occurred. The number of outcomes and their distribution according to mortality risk indicated close agreement between observed and predicted results. Thus, a quality-assurance technique developed in tertiary care centers can be used to indicate a comparable level of care in a community hospital.