Efficacy and outcomes of balloon pulmonary angioplasty in elderly vs non-elderly chronic thromboembolic pulmonary hypertension patients

Introduction

Balloon pulmonary angioplasty (BPA) has been reported as an effective and safe treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, its safety and efficacy in elderly patients remains unknown.

Purpose

We investigated the effect of BPA on hemodynamics and respiratory parameters, functional capacity, and short- and long-term outcome in elderly patients.

Methods

From November 2012 to May 2018, 141 consecutive CTEPH patients who underwent BPA in a single university hospital were enrolled (age: 65 [54.5–74] years old, WHO functional class [WHO-FC] II/III/IV; 35/96/10). Patients were divided into two groups according to the age; elderly (≥75 years, N=32) and young groups (<75 years, N=109). Hemodynamics (right-sided heart catheterization), biomarkers (brain natriuretic peptide), respiratory function (spirometry and diffusion capacity measurement), and functional capacity (6-minute walk distance [6MWD] and WHO-FC) were evaluated at baseline and 1-year post BPA. Procedure-related complications (in hospital death, use of percutaneous cardiopulmonary support [PCPS], and pulmonary injury) and all cause death during the follow up period were also assessed.

Results

At baseline, although elderly group had less severe hemodynamics (mPAP: 33.1±6.7 vs 39.0±11.8 mmHg, p<0.05), they had poor exercise capacity and reduced pulmonary diffusion capacity, compared with young group (6MWD: 264.6±101.3 vs 369.7±105.2 m, %DLco: 42.0±12.0 vs 50.2±12.7%, all p<0.05). BPA improved hemodynamics, biomarkers, exercise capacity, and pulmonary diffusion capacity in both elderly and young groups (all p<0.05). There was no in-hospital death or use of PCPS in both groups, although the incidence of pulmonary injury was higher in elderly group (14.3% vs 5.3%, p<0.01). Under the normalized hemodynamics 1-year after BPA in both groups, exercise capacity and pulmonary diffusion capacity were worse in the elderly group than young groups (p<0.01). The incidence of all-cause death in the follow up period was higher in elderly group, all of which were due to non-pulmonary hypertension (PH)-related death (p<0.01).

Conclusion

BPA was effective in improving hemodynamics and respiratory parameters and functional capacity, in associated with no critical complication, regardless of the age. Elderly patients who were treated with BPA were associated with higher incidence of non-PH-related death.

Changes of mean PAP in the two groups

Funding Acknowledgement

Type of funding source: None

A novel causative gene variant, TNFRSF13B p.Gly76Ser, in patients with pulmonary arterial hypertension

Background

Pulmonary artery hypertension (PAH) is a poor prognostic disease. Some causative genes were reported as the PAH-associated genes. However, the pathogenetic variants in PAH-associated genes have not been identified in majority of patients with idiopathic PAH.

Purpose

Our aim was to investigate the new causative gene variants associated with PAH.

Methods

We performed whole-exome sequencing in 272 patients with idiopathic/heritable PAH. Structural analysis simulation was performed to define how the candidate gene variant affected the structure of protein.

Results

We identified the heterozygous substitution change of c.226G>A (p.Gly76Ser, rs146436713) in tumor necrotic factor receptor superfamily 13B gene (TNFRSF13B) (NM_012452.2) in 6 (2.2%) patients with idiopathic/heritable PAH, although the allele frequency of this rare variant is 0% in Integrative Japanese Genome Variation Database (control population database). Two of the six cases were blood relatives, although they did not have the known causative gene variants of PAH. One of these two relatives died of right heart failure despite the combination medical therapy, and her pathological anatomy demonstrated intimal thickening and medial hypertrophy in the pulmonary arteries, formation of plexiform lesions (Heath-Edwards classification grade V). Time-lapse images from structural analysis simulation showed the instability of N-terminal in the protein, which regulates the vascular inflammation, synthesized from TNFRSF13B p.Gly76Ser variant (Figure), suggesting that p.Gly76Ser variant may be involved in the development of PAH via aberrant inflammation in pulmonary vessels.

Conclusions

TNFRSF13B p.Gly76Ser variant is a candidate of causative gene variant for PAH.

Structural analysis of proteins

Funding Acknowledgement

Type of funding source: None

De-escalation/discontinuation of oxygen-therapy and medication is feasible and safe in chronic thromboembolic pulmonary hypertension patients treated with balloon pulmonary angioplasty

Introduction

There has been increasing evidence of the efficacy of balloon pulmonary angioplasty (BPA) in improving the hemodynamics, exercise capacity, and biomarkers of patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, there is no consensus on the adjustment of home oxygen therapy (HOT) and pulmonary hypertension (PH)-specific medications after BPA in patients with CTEPH.

Purpose

We aimed to examine the current status of the de-escalation/discontinuation of HOT and PH-specific medications post-BPA, and clarify its effect on subsequent hemodynamics, biomarkers, and long-term clinical outcomes.

Methods and results

From November 2012 to July 2019, 134 consecutive CTEPH patients who underwent BPA at a single university hospital were enrolled (age; 63.6±13.4 years, female; n=87 [64.9%], WHO functional class [WHO-FC] II/III/IV; 33/92/9). Hemodynamic data, functional capacity (6-minute walk distance and WHO-FC), biomarkers (brain natriuretic peptide [BNP] and high-sensitivity troponin T [hs-TropT]), and respiratory function were evaluated at baseline, immediately and 1 year post-BPA. Clinical outcomes (all-cause death and heart failure [HF] admission) were also assessed during the follow up period. The total number of sessions was 6.3±2.0, and the number of target vessels was 14.3±2.0. Mean pulmonary arterial pressure decreased from 37.8±11.2 to 20.4±5.1 mmHg 1-year after BPA (p<0.01). The proportion of patients who required HOT (at rest or on exertion) and combination medical therapy (≥2 PH-specific medications) decreased 1 year post-BPA (from 59.0% to 7.5%, and from 41.8% to 10.4%, respectively; Figure). Among 79 patients who required HOT during daytime, 64 patients (81.0%) discontinued HOT just after BPA completion. Among 56 patients who required combination medical therapy, 29 (51.8%) discontinued combination therapy. Baseline factors influencing the continuation of HOT and combination medical therapy post-BPA were almost identical (i.e. lower exercise capacity and pulmonary diffusion capacity, and worse hemodynamics). Results showed that discontinuation of HOT and combination medical therapy did not affect the maintenance of improved hemodynamics and levels of BNP and hs-TropT, and no adverse clinical outcomes (all-cause death and HF hospitalization) were observed during 1 year post-BPA.

Conclusions

Most CTEPH patients discontinued HOT and PH-specific combination medical therapy after BPA, which was not associated with the deterioration of hemodynamics, functional capacity, or biomarkers. No adverse long-term outcomes were observed. De-escalation/discontinuation of HOT and PH-specific combination medical therapy after BPA is feasible and safe for patients with CTEPH.

De-escalation of HOT and medical therapy

Funding Acknowledgement

Type of funding source: None

P6009Poor outcomes in pulmonary arterial hypertension as a member of RNF213-associated vascular diseases

Background

A variant of c.14429G>A (p.Arg4810Lys, rs112735431) in the ring finger protein 213 gene (RNF213; NM_001256071.2) has been recently identified as a risk allele for pulmonary arterial hypertension (PAH), suggesting that PAH can be added as a new member of RNF213-associated vascular diseases including Moyamoya disease and peripheral pulmonary stenosis.

Purpose

Our aim was to identify the clinical features and outcomes of PAH patients with RNF213 p.Arg4810Lys variant.

Methods

Whole-exome sequencing was performed in 139 idiopathic (or possibly heritable) PAH patients. Hemodynamics and prognosis were evaluated in the patients with RNF213 p.Arg4810Lys variant and the patients with bone morphogenic protein receptor type 2 (BMPR2) mutations.

Results

The RNF213 p.Arg4810Lys variant was identified in a heterozygous state in 11 patients (7.9%). Time-course changes in hemodynamics after combination therapy in the patients with the RNF213 p.Arg4810Lys variant were significantly poorer compared with those in BMPR2 mutation carriers (n=36) (comparison of changes in mean pulmonary arterial pressure, P=0.007). The event-free rate of death or lung transplantation was significantly poorer in RNF213 p.Arg4810Lys variant carriers than in BMPR2 mutation carriers (5-year event-free rate since the introduction of prostaglandin I2 infusion, 0% vs. 93%, P<0.001) (Figure).

Time to death or lung transplantation

Conclusions

PAH patients with the RNF213 p.Arg4810Lys variant were associated with a poor reactivity to vasodilator drugs and poor clinical outcomes even in the recent era. Earlier consideration of lung transplantation might be required for RNF213 p.Arg4810Lys variant carriers developing PAH. Documentation of the RNF213 p.Arg4810Lys variant, as well as already known pathogenic genes, can provide clinically relevant information for therapeutic strategies, leading to a personalized approach for the treatment of PAH.

Durability of Flexible Molded Polyurethane Foams

In recent years, we have developed highly resilient (HR) flexible molded foams with superb durability, resilience and vibration characteristics, and we have reported that these improvements were based on control of cross link degree of polymer, morphology and mobility of hard and soft segments. This paper describes factors that dominantly influence the durability and the mechanism of fatigue by investigation of cross linking by covalent and hydrogen-bonds and the morphology of hard/soft segments. In this study, we use molded foams with different durabilities. These are TDI-based high performance/conventional HR, MDI-based high-performance/conventional HR, and hot molded foams.

On the whole, a small apparent viscosity coefficient, which is calculated from vibration characteristics of the foam, and a higher cross link degree of foam polymer make static and dynamic durability of flexible molded foam better. Mobility of the soft segment, estimated by solid state NMR, also dominates dynamic durability. Accordingly, hydrogen-bonds of the hard segment contribute against creep as a cross link point in static/dynamic durability test, and tight hydrogen-bonds of hot molded foam are durable against rupture or rebonding by water molecules in the wet compression set oven.

The drop in cross link degree of foam polymer was not observed during vibration durability test. Accordingly, the mechanism of fatigue could be the change of state in hydrogen-bonds or tangling of polymer-chains, or relatively macro rupture.

A 12 month in vivo study on the response of bone to a hydroxyapatite–polymethylmethacrylate cranioplasty composite

We investigated the osteoconductivity and biocompatibility in vivo of a new hydroxyapatite-polymethylmethacrylate (HA-PMMA) composite developed for use as an implant material for cranioplasty, which is expected to have the good osteoconductivity of HA together with the strength and ease of handling of PMMA. The HA-PMMA composites were implanted in eight full-grown beagles and then 6, 12, 24 weeks and 1 year after implantation, the animals were sacrificed and the implanted materials removed along with the surrounding tissues. Extirpated specimens were studied using an optical microscope and micro-computed tomography (micro-CT). Fibrous connective tissue was prominent in the interface of the composite at 6 weeks. New bone formation was seen around the implant, 12 and 24 weeks after operation. At 1 year, new bone filled in the interface of the HA-PMMA composite and adhered to the surrounding autogenous bone. Mixing HA and PMMA did not interfere with the osteoconductivity of the HA component. In micro-CT findings, the new bone growing on the HA-PMMA composite could be seen attaching preferentially to HA particles exposed at the composite surface, rather than the PMMA. This study demonstrated that this HA-PMMA composite is a good candidate for cranial bone implants due to its good osteoconductivity and biocompatibility.

Adenosine receptor antagonists cancelled the ischemic tolerance phenomenon in gerbil

Pretreatment of the brain with sublethal ischemia has been reported to induce neuronal resistance to otherwise lethal ischemia, a phenomenon designated as ischemic tolerance. The protective mechanisms of the phenomenon are not known yet, however, recent experimental data suggest the involvement of adenosine receptor activation in the acquisition of tolerance. In this study, the effect of theophylline, a non-selective adenosine receptor antagonist, and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 receptor antagonist, were investigated to ascertain if these drugs could cancel the protective effect of ischemic tolerance in the gerbil. DPCPX or theophylline was administered at 3 h after a short preconditioning ischemia, and 21 h later animals were subjected to lethal ischemia of 5 min duration. DPCPX at a dose of 1.0 mg/kg (i.p) and theophylline at a dose of 20 mg/kg (i.p) significantly reduced the protective effect of preconditioning in the CA1 hippocampal neurons. These findings suggest the involvement of adenosine receptor activation for the development of ischemic tolerance phenomenon.

Chromatographic separation of a small subunit (PsbW/PsaY) and its assignment to Photosystem I reaction center

By using a hydroxyapatite column, the five major Photosystem I (PSI) subunits (PsaA,-B,-C,-D,-E) solubilized by sodium dodecyl sulfate (SDS) were fractionated from a spinach PSI reaction center preparation. Another small (5-6 kDa) polypeptide was also separated, and purified to homogeneity. Mass spectroscopy yielded its molecular weight to be 5942 +/- 10. This polypeptide had an N-terminal sequence homologous to those of previously reported 5-kDa subunits from spinach and wheat and a 6.1-kDa subunit of Chlamydomonas, which had all been assigned to Photosystem II (PSII) and designated as PsbW. However, we found similar 5-kDa polypeptides with highly conserved N-terminal sequences ubiquitously in PSI particles from other plants including Daikon (Raphanus sativus, Japanese radish), Chingensai (Brassica parachinensis, Chinese cabbage), parsley and Shungiku (Chrysanthemum coronarium, Garland chrysanthemum) as well. Preparations of spinach PSI particles prepared by using a mild detergent (digitonin) had this 5-kDa subunit, while PSII particles did not. Moreover, a bare-bone PSI reaction center preparation consisting of PsaA/B alone had a more than stoichiometric amount of this 5-kDa polypeptide. A mechanically (without detergent) fractionated stroma thylakoid preparation from Phytolacca americana, which lacked other PSII subunits, also contained this 5-kDa subunit. Thus, we propose that this 5-kDa polypeptide, previously designated as a PSII subunit (PsbW), is an integral subunit of PSI as well.

Cellular roles in relapse processes of experimentally-moved rat molars

This histological study was designed to clarify the relapse processes of rat molars following orthodontic tooth movement by the Waldo method. An elastic band was inserted between the upper first and second molars, and removed either 7 or 21 days later. The relapse processes of first molars were examined at 1 or 4 days after completing the 7-day-insertion and at 5 or 10 days after the end of the 21-day-insertion. At the end of the 7-day-insertion period, the mean interdental space was 158 microns, but decreased rapidly, reaching 44 microns by 1 day after removal, and 16 microns by day 4. In the periodontal ligament (PDL) compressed by elastic band insertion, partial hyalinization and/or mineralization occurred. The stretched PDL consisted of irregularly-distributed, thin principal fibres, approximately 2.4 microns in diameter. On days 1 and 4 after removal, osteoclasts, macrophage-like cells and fibroblast-like cells were localized around hyalinized tissues, but thick principal fibres, approximately 3.8 microns in diameter, were regularly distributed throughout the PDL proper. The mean interdental space after the 21-day-insertion was 536 microns, but this had decreased to 108 microns by day 5, and 71 microns by day 10. On day 5 after removal, numerous osteoclasts were evenly distributed in the compressed PDL, while thick principal fibres, approximately 3.5 microns, were present in the stretched PDL. These results suggest that, during relapse of experimentally-moved rat molars, (i) rapid remodelling of the PDL and surrounding alveolar bones is the main cause of tooth relapse and (ii) hyalinized and/or mineralized tissues occurred by compression are rapidly resorbed by osteoclasts, macrophage-like cells and fibroblast-like cells.

Persistent primitive hypoglossal artery complicated by atrial septal defect and congenital intrahepatic shunts

During early embryogenesis, anastomoses are formed between the carotid artery and the basilar or the vertebral artery, and subsequently, these anastomoses regress. In some cases, these anastomoses remain as persistent carotid-basilar or carotid-vertebral anastomoses. Atrial septal defect (ASD), a communication between the atria at the septal level, is a congenital heart anomaly. Intrahepatic venous shunts between the portal and hepatic veins are very rare and only some are considered congenital. We present the first case report of a patient with an ASD, a persistent primitive hypoglossal artery, and congenital portahepatic shunts.

Activation of cytosolic phospholipase A2 by platelet-derived growth factor is essential for cyclooxygenase-2-dependent prostaglandin E2 synthesis in mouse osteoblasts cultured with interleukin-1

The synthesis of prostaglandins (PGs) is regulated by the arachidonic acid release by phospholipase A2 (PLA2) and its conversion to PGs by cyclooxygenase (COX). In the present study, we examined the regulation of PG synthesis by interleukin (IL)-1alpha in primary mouse osteoblastic cells isolated from mouse calvaria. Although IL-1alpha greatly enhanced cox-2 mRNA expression and its protein levels, PGE2 was not produced until 24 h. When arachidonic acid was added to osteoblastic cells precultured with IL-1alpha for 24 h, PGE2 was produced within 10 min. Of several growth factors tested, platelet-derived growth factor (PDGF) specifically initiated the rapid synthesis of PGE2, which was markedly suppressed by a selective inhibitor of cox-2 (NS-398). In mouse osteoblastic cells, cytosolic PLA2 (cPLA2) mRNA and its protein were constitutively expressed and increased approximately 2-fold by IL-1alpha, but secretory PLA2 mRNA was not detected. PDGF rapidly stimulated PLA2 activity, which was blocked completely by a cPLA2 inhibitor (arachidonyltrifluoromethyl ketone). The PDGF-induced cPLA2 activation was accompanied by phosphorylation of its protein. These results indicate that cox-2 induction by IL-1alpha is not sufficient, but cPLA2 activation by PDGF is crucial for IL-1alpha-induced PGE2 synthesis in mouse osteoblasts.

Expression of c-fos-like protein in the rat brain after injection of interleukin-1-beta into the gingiva

Expression of the c-fos proto-oncogene in the rat brain was examined by immunostaining for fos, the nuclear protein product of the c-fos gene, after injection of interleukin-1-beta (IL-1 beta) into the gingiva of an incisor. The distribution pattern of labelled cells was compared with that induced by tooth pulp stimulation. Neurons that express fos-immunoreactivity (fos-IR) appeared in several regions in the neuraxis 1.5 h after IL-1 beta injection, peaked at 2 h, and then declined. Labelled cells were found bilaterally in regions that contribute to pain-relay and pain-inhibition. The distribution of labelled cells almost matched the pattern induced by noxious tooth pulp stimulation. In indomethacin-pretreated animals, no neurons expressing fos-IR were found in nuclei associated with relay of nociception nor in nuclei contributing to inhibition of nociception. The results suggest that a small amount of IL-1 beta at the site of periodontal disease can induce fos-IR in brain neurons through increased prostaglandin production.

Continuously applied compressive pressure induces bone resorption by a mechanism involving prostaglandin E2 synthesis

In previous research, we devised a specific culture chamber to examine the effect of continuously applied compressive pressure (CCP) on bone formation and resorption. The chamber was infused with compressed mixed gases with different O2 and CO2 composition to maintain the pO2, pCO2, and pH in the culture medium under pressures of +0.5 atm (1.5 atm total) to +2.0 atm (3.0 atm total) at the same levels as those at the ordinary pressure (1 atm). Using the specific culture chamber, we demonstrated that CCP greatly suppressed the differentiation of mouse osteoblast-like MC3T3-E1 cells. The inhibition by CCP appeared to be mediated by prostaglandin E2 (PGE2). In the present study, we examined the effect of CCP on osteoclastic bone resorption. CCP treatment of mouse bone marrow culture markedly increased both the PGE2 production and the number of tartrate-resistant acid phosphatase (TRACP)-positive mononuclear cells (possibly precursors of multinucleated osteoclasts). An autoradiographic study using [125I]-salmon calcitonin showed clearly that those TRACP-positive cells had calcitonin receptors. The CCP effect was the greatest at +1.0 atm (2.0 atm total). Isobutylmethylxanthine potentiated the production of TRACP-positive cells induced by CCP. Adding indomethacin completely inhibited both the TRACP-positive cell formation and the PGE2 production induced by CCP. CCP also increased the release of 45Ca from prelabeled mouse calvaria during later stages (2-6 days) of the 6-day culture period. CCP markedly increased PGE2 but not interleukin 1 in the culture media of mouse calvaria. These results indicate that, besides inhibiting osteoblast differentiation, CCP stimulates bone resorption by generating new osteoclasts through a mechanism involving PGE2 production.

Effect of a continuously applied compressive pressure on mouse osteoblast-like cells (MC3T3-E1) in vitro

Bone metabolism is often affected by a variety of mechanical forces, but the cytological basis of their action is not known. In this study, we examined the effect of a continuously applied compressive pressure (CCP) on the growth and differentiation of clonal mouse osteoblast-like cells (MC3T3-E1) cultured in a specifically devised culture chamber. The gas phase of the chamber was maintained at a pressure of 2 atmospheres (atm) above ambient (3 atm total, 3.1 kg/cm2; 3.0 x 10(5) Pa) by continuously infusing a compressed mixed gas (O2: N2:CO2 = 7.0%:91.3%:1.7%). The pO2, pCO2, and pH in the culture medium at 37 degrees C under 3 atm were maintained at the same levels as those under 1 atm. MC3T3-E1 cells were cultured in alpha-minimal essential medium containing 10% fetal bovine serum under either 3 atm in the CCP culture chamber or 1 atm in an ordinary CO2 incubator. Alkaline phosphatase activity, a marker of osteoblasts, was greatly suppressed by the CCP treatment. The inhibition of alkaline phosphatase activity was rapidly restored when the cells were transferred to an ordinary CO2 incubator under 1 atm, indicating that the inhibition of alkaline phosphatase activity by CCP is reversible. Cell growth was not altered under CCP. The CCP treatment greatly increased the production and secretion of prostaglandin E2 (PGE2). Adding either conditioned medium from the CCP culture or exogenous PGE2 to the control culture under 1 atm suppressed alkaline phosphatase activity dose-dependently. The CCP treatment also suppressed collagen synthesis and calcification. These results suggest that CCP causes the cells to produce and secrete PGE2, which, in turn, inhibits differentiation of osteoblasts and the concomitant calcification.