The effect of inhaled budesonide on the maximal degree of airway narrowing to leukotriene D4 and methacholine in normal subjects in vivo

In normal humans in vivo, maximal airway narrowing to LTD4 is more severe than to methacholine. Moreover, LTD4 heightens the maximal response to methacholine for several days. To investigate whether or not this is due to inflammatory changes in the airway wall, we studied the effects of the corticosteroid budesonide on the dose-response curves to inhaled LTD4 and to methacholine. In a two-period, double-blind, placebo-controlled design, budesonide (400 micrograms twice a day) or placebo was inhaled by eight normal subjects on six consecutive days, with a 3-wk washout. Complete dose-response curves to LTD4 (0.36 to 43 nmol) were performed on Day 5, and to methacholine (1.28 to 655 mumol) on Days 4 and 6 of each period using a validated method. The response was measured by FEV1 and standardized partial expiratory flow-volume curves (V40p), and was expressed as the percent fall from baseline. A maximal response plateau was considered if more than two doses fell within a 5% response range. All subjects reached plateaus to methacholine and to LTD4. Budesonide reduced the maximal response to LTD4 (mean difference with placebo, 7.9% fall for FEV1, and 8.4% fall for V40p; p less than 0.05). During placebo the maximal response to methacholine 24 h after LTD4 was higher than 24 h before (mean change, 2.7% fall in FEV1 and 5.5% fall in V40p; p less than 0.05), but not during budesonide (mean change, -2.5% fall in FEV1 and -0.1% fall in V40p; p greater than 0.2), the changes being significantly different between the two periods (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrocardiographic changes and conduction disturbances after transfemoral aortic valve implantation with Edwards Sapien 3 prosthesis

Objectives

The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI).

Predicting Vertical Jump Height from Bar Velocity

The objective of the study was to assess the use of maximum (V_max) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s^-2). Vertical jump height was calculated from the take-off velocity (V_take-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the V_max and FPV recorded by the linear velocity transducer. V_max (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and V_take-off was observed (r² = 0.307), while the differences between V_max and V_take-off were homogenously distributed (r² = 0.071). These results suggest that V_max is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine.

Key points

• Vertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.
• The relationship between the point at which bar acceleration is less than -9.81 m·s^-2 and the real take-off is affected by the velocity of movement.
• Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.

Key words: Linear velocity transducer, force platform, jump performance, swimming     

Accurate molecular diagnosis of phenylketonuria and tetrahydrobiopterin-deficient hyperphenylalaninemias using high-throughput targeted sequencing

Genetic diagnostics of phenylketonuria (PKU) and tetrahydrobiopterin (BH4) deficient hyperphenylalaninemia (BH4DH) rely on methods that scan for known mutations or on laborious molecular tools that use Sanger sequencing. We have implemented a novel and much more efficient strategy based on high-throughput multiplex-targeted resequencing of four genes (PAH, GCH1, PTS, and QDPR) that, when affected by loss-of-function mutations, cause PKU and BH4DH. We have validated this approach in a cohort of 95 samples with the previously known PAH, GCH1, PTS, and QDPR mutations and one control sample. Pooled barcoded DNA libraries were enriched using a custom NimbleGen SeqCap EZ Choice array and sequenced using a HiSeq2000 sequencer. The combination of several robust bioinformatics tools allowed us to detect all known pathogenic mutations (point mutations, short insertions/deletions, and large genomic rearrangements) in the 95 samples, without detecting spurious calls in these genes in the control sample. We then used the same capture assay in a discovery cohort of 11 uncharacterized HPA patients using a MiSeq sequencer. In addition, we report the precise characterization of the breakpoints of four genomic rearrangements in PAH, including a novel deletion of 899 bp in intron 3. Our study is a proof-of-principle that high-throughput-targeted resequencing is ready to substitute classical molecular methods to perform differential genetic diagnosis of hyperphenylalaninemias, allowing the establishment of specifically tailored treatments a few days after birth.     

Kinase-independent function of checkpoint kinase 1 (Chk1) in the replication of damaged DNA

The checkpoint kinases Chk1 and ATR are broadly known for their role in the response to the accumulation of damaged DNA. Because Chk1 activation requires its phosphorylation by ATR, it is expected that ATR or Chk1 down-regulation should cause similar alterations in the signals triggered by DNA lesions. Intriguingly, we found that Chk1, but not ATR, promotes the progression of replication forks after UV irradiation. Strikingly, this role of Chk1 is independent of its kinase-domain and of its partnership with Claspin. Instead, we demonstrate that the ability of Chk1 to promote replication fork progression on damaged DNA templates relies on its recently identified proliferating cell nuclear antigen-interacting motif, which is required for its release from chromatin after DNA damage. Also supporting the importance of Chk1 release, a histone H2B-Chk1 chimera, which is permanently immobilized in chromatin, is unable to promote the replication of damaged DNA. Moreover, inefficient chromatin dissociation of Chk1 impairs the efficient recruitment of the specialized DNA polymerase η (pol η) to replication-associated foci after UV. Given the critical role of pol η during translesion DNA synthesis (TLS), these findings unveil an unforeseen facet of the regulation by Chk1 of DNA replication. This kinase-independent role of Chk1 is exclusively associated to the maintenance of active replication forks after UV irradiation in a manner in which Chk1 release prompts TLS to avoid replication stalling.