PARP inhibitor rucaparib induces changes in NAD levels in cells and liver tissues as assessed by MRS

Poly(adenosine diphosphate ribose) polymerases (PARPs) are multifunctional proteins which play a role in many cellular processes. Namely, PARP1 and PARP2 have been shown to be involved in DNA repair, and therefore are valid targets in cancer treatment with PARP inhibitors, such as rucaparib, currently in clinical trials. Proton magnetic resonance spectroscopy (¹H‐MRS) was used to study the impact of rucaparib in vitro and ex vivo in liver tissue from mice, via quantitative analysis of nicotinamide adenosine diphosphate (NAD⁺) spectra, to assess the potential of MRS as a biomarker of the PARP inhibitor response. SW620 (colorectal) and A2780 (ovarian) cancer cell lines, and PARP1 wild‐type (WT) and PARP1 knock‐out (KO) mice, were treated with rucaparib, temozolomide (methylating agent) or a combination of both drugs. ¹H‐MRS spectra were obtained from perchloric acid extracts of tumour cells and mouse liver. Both cell lines showed an increase in NAD⁺ levels following PARP inhibitor treatment in comparison with temozolomide treatment. Liver extracts from PARP1 WT mice showed a significant increase in NAD⁺ levels after rucaparib treatment compared with untreated mouse liver, and a significant decrease in NAD⁺ levels in the temozolomide‐treated group. The combination of rucaparib and temozolomide did not prevent the NAD⁺ depletion caused by temozolomide treatment. The ¹H‐MRS results show that NAD⁺ levels can be used as a biomarker of PARP inhibitor and methylating agent treatments, and suggest that in vivo measurement of NAD⁺ would be valuable.     

Graft-versus-host disease after liver transplantation is associated with bone marrow failure,hemophagocytosis, and DNMT3A mutations

Graft-versus-host disease after liver transplantation (LT-GVHD) is rare, frequently fatal, and associated with bone marrow failure (BMF), cytopenias, and hyperferritinemia. Given hyperferritinemia and cytopenias are present in hemophagocytic lymphohistiocytosis (HLH), and somatic mutations in hematopoietic cells are associated with hyperinflammatory responses (clonal hematopoiesis of indeterminate potential, CHIP), we identified the frequency of hemophagocytosis and CHIP mutations in LT-GVHD. We reviewed bone marrow aspirates and biopsies, quantified blood/marrow chimerism, and performed next-generation sequencing (NGS) with a targeted panel of genes relevant to myeloid malignancies, CHIP, and BMF. In all, 12 marrows were reviewed from 9 LT-GVHD patients. In all, 10 aspirates were evaluable for hemophagocytosis; 7 had adequate DNA for NGS. NGS was also performed on marrow from an LT cohort (n = 6) without GVHD. Nine of 10 aspirates in LT-GVHD patients showed increased hemophagocytosis. Five (71%) of 7 with LT-GVHD had DNMT3A mutations; only 1 of 6 in the non-GVHD LT cohort demonstrated DNMT3A mutation (p = .04). Only 1 LT-GVHD patient survived. BMF with HLH features was associated with poor hematopoietic recovery, and DNMT3A mutations were over-represented, in LT-GVHD patients. Identification of HLH features may guide prognosis and therapeutics. Further studies are needed to clarify the origin and impact of CHIP mutations on the hyperinflammatory state.

     

Impact of oral potentially malignant disorders on quality of life

Background

Oral potentially malignant disorders (OPMDs) could have a significant psychological impact on patients, principally because of the unknown risk of malignant transformation, while the physical and functional impairments could differ. This study aimed to assess the impact of three different OPMDs and their disease stages on the quality of life (QoL) of affected patients.

Methods

Oral leukoplakia (OL), oral lichen planus (OLP) and oral submucous fibrosis (OSF) patients who were undergoing treatment at an oral medicine clinic of a dental teaching hospital in India were the study population. All subjects completed the recently developed OPMDQoL questionnaire and a short form 12 item (version 2) health survey questionnaire (SF‐12v2). OPMDQoL questionnaire consists of 20 items over four dimensions. A higher score denotes poor OHRQoL. SF‐12v2 has two components, a Physical Component Summary (PCS) and Mental Component Summary (MCS).

Results

A total of 150 subjects (50 each of OL, OLP and OSF) participated. OL patients (37.7 ± 7.9) reported significantly better OPMDQoL scores than OLP (47.3 ± 5.8) and OSF (45.4 ± 9.2) patients. OLP patients reported significant problems in obtaining a clear diagnosis for their condition, more so than the other OPMDs. OL patients reported fewer problems for the dimension, “physical impairment and functional limitations” than the OLP and OSF patients. A significant trend was observed with the overall OPMDQoL and MCS, deteriorating as the disease stage increased.

Conclusions

OLP and OSF have a significant impact on the QoL of affected individuals: OL less so. Increasing stage of the disease is associated with worsening QoL.     

Force and time gain interact to nonlinearly scale adaptive visual-motor isometric force control

This study examined the influence of force–time gain on the visual-motor control of isometric force. The spatial lengths on the computer screen representing the unit of elapsed time (time gain) and force (force gain) of the force output were compressed or extended in a crossed fashion while subjects produced index finger abduction force to a sinewave and constant force target that was 20 % of maximal voluntary contraction. The results revealed a U-shaped interactive influence of force–time gain on force performance, namely a particular combination of moderate force–time gains leads to optimal force performance. The nature of the interaction between the force and time gains also differed depending on the task demand. During constant force production, the best gain at one dimension (force or time) was invariant across the other dimension (time or force), whereas during sinewave force production, the best gain at one dimension varied with the gain at the other dimension. The results support the proposition that the control of force output is organized by the interactive influence of different categories of constraints where the influence of visual information gain depends on the dynamics of the force control and the task demand. The findings also provide implications for visual gain parameter settings for adaptive force control.     

The effects of foot position and orientation on inter- and intra-foot coordination in standing postures: a frequency domain PCA analysis

We investigated the effect of foot position and foot orientation on asymmetrical body weight loading and the inter- and intra-foot coordination dynamics of standing postures. The participants were instructed to stand with the feet side-by-side and in staggered and tandem positions with the right foot oriented at different angles (30, 60 and 90°). The results showed that the participants naturally loaded more on their left foot when positioned with their right foot forward. As the orientation of the right foot was changed from 90 to 30°, they loaded a significantly large proportion of their body weight on their left foot and the degree of coordination of the 4 COP time series increased. Foot position, constrains both the area of the base of support and the loading of the feet, played an important role differentiating the contribution of each COP to the postural control system. In particular, when postural stance was challenged by the limitation of the base of support, the COPs in the unstable plane (inter-foot coordination) showed larger factor weightings. In contrast, when standing posture was not challenged by the base of support boundary, the COPs of the more loaded foot (intra-foot coordination) dominated foot coordination in postural control. These findings show that the mechanical constraints of foot position and orientation interact to channel different patterns of inter- and intra-foot coordination dynamics of standing postures.