Impact of contractures on daily functioning in adolescents with spinal muscular atrophy: a qualitative study

PURPOSE

Exploring the impact of contractures in adolescents and young adults (AYA) with spinal muscular atrophy (SMA) on daily functioning and participation and the impact of received contracture management.

METHODS

We included 14, non-ambulant AYA with SMA types 2/3 (10 females and 4 males), aged 16-30 years. Interviews focused on two topics: perceived impact of contractures on daily functioning and of previous contracture management. We used inductive thematic analysis for interview analysis.

RESULTS

In general, participants experienced muscle weakness to be more of a hindrance than contractures; they had adapted to their contractures over time. Participants considered contracture treatment useful when goals were meaningful and realistic. Participants mentioned that their perspective on contracture management would change in light of a promise of improved motor function due to disease-modifying treatment.

CONCLUSION

Despite the relatively low impact of contractures in comparison to the loss of muscle strength, non-ambulant AYA with SMA should be informed on the potential impact of contractures and benefits and potential adverse effects of their management. This information can support the shared decision-making process. While respecting individual choices, allows for incorporating interventions into daily life and the promotion of daily functioning and participation when children with SMA are growing up.

Atrial extrasystoles unmask early electropathology in pediatric congenital heart disease

Background

Despite improvement in (timing of) of intervention or surgery, atrial fibrillation (AF) still occurs more often and at a younger age in patients with congenital heart disease (CHD) than in the general population. This suggests that in this population atrial conduction is already affected in an early stage.

Purpose

To unmask early, enhanced non-uniform anisotropic atrial conduction in pediatric patients with CHD by examining the impact of spontaneous aberrant atrial extrasystoles (AES) on atrial conduction.

Methods

Twenty-one pediatric patients with various CHD (mild 43%, moderate 24% and severe 33%) (median age=1.8 years [0.2–7.3]) undergoing primary cardiac surgery were included for an intra-operative epicardial mapping of both atria, including Bachmann's bundle. Conduction velocity (CV), localized areas of conduction delay and/or block (CD, CB and continuousCDCB) and unipolar electrogram (EGM) characteristics (voltages and amount of fractionated potentials) were quantified during sinus rhythm (SR) and compared with corresponding AES beats.

Results

During 41 AES median unipolar voltage and CV decreased compared to corresponding SR beats (7.08 [5.50–9.10] mV vs. 5.71 [3.95–7.48] mV, p<0.001); 87.9 [76.7–101.6] cm/s vs. 84.5 [73.0–93.6] cm/s, p=0.013; respectively), whereas the amount of fractionated potentials increased (12.7 [3.5–18.2] % vs. 19.5 [10.5–30.0] %, p<0.001). Conduction disorders, consisting of CD, CB and cCDCB, were more prominent during AES (4.5 [2.3–6.3] %; 1.5 [0.0–4.3] %; 6.3 [2.6–11.2] %, respectively) (all p≤0.006). Differences in EGM morphology and conduction heterogeneity were not influenced by the degree of the prematurity of AES (p>0.05).

Conclusions

AES in pediatric patients with CHD cause localized areas of conduction slowing and block, potentials with lower unipolar voltages and a higher degree of fractionation compared to SR potentials, independent of its prematurity. Our findings indicate that in pediatric patients with CHD, early, enhanced non-uniform anisotropic atrial conduction is already present and can be unmasked by AES. These insights are the first step in further understanding the time course of AF in CHD patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CVON-AFFIPNWO-Vidi

Influence of Ion Source Geometry on the Repeatability of Topographically Guided LAESI-MSI

Spatially resolving the relative distribution of analyte molecules in biological matter holds great promise in the life sciences. Mass spectrometry imaging (MSI) is a technique that can provide such spatial resolution but remains underused in fields such as chemical ecology, as traditional MSI sample preparation is often chemically or morphologically invasive. Laser ablation electrospray ionization (LAESI)-MSI is a variation of MSI particularly well-suited for situations where chemical sample preparation is too invasive but provides new challenges related to the repeatability of measurement outcomes. We assess the repeatability of LAESI-MSI by sampling a droplet of [ring-¹³C₆]l-phenylalanine with known concentration and expressing the resulting variability as a coefficient of variation, c_v. In doing so, we entirely eliminate variability caused by surface morphology or underlying true sample gradients. We determine the limit of detection (LOD) for¹³C₆-Phe by sampling from droplets with successively decreasing but known concentration. We assess the influence of source geometry on the LOD and repeatability by performing these experiments using four distinct variations of sources: one commercial and three custom-built ones. Finally, we extend our study to leaf and stem samples Arabidopsis thaliana and Gossypium hirsutum. We overcome the challenges of LAESI associated with three-dimensional surface morphology by relying on work previously published. Our measurements on both controlled standard and realistic samples give strong evidence that LAESI-MSI's repeatability in current implementations is insufficient for MSI in chemical ecology.

Bulbar Problems Self-Reported by Children and Adults with Spinal Muscular Atrophy

BACKGROUND

Spinal muscular atrophy (SMA) is hereditary motor neuron disorder, characterised by the degeneration of motor neurons and progressive muscle weakness. It is caused by the homozygous loss of function of the survival motor neuron (SMN) 1 gene. SMA shows a wide variability of disease severity.

OBJECTIVE

To investigate self-reported bulbar problems in patients with SMA, and their relationship to age, functional motor scores and active maximum mouth opening.

METHODS

We used the Diagnostic List of Dysphagia and Dysarthria in (pediatric) patients and relevant recent clinical data from the national SMA database.

RESULTS

The 118 included patients with SMA frequently reported jaw problems (34%), fatigue associated with mastication (44%), choking (56%) and intelligibility problems (27%). Jaw, mastication and swallowing problems frequently occurred in combination with each other. There was an increase of reported bulbar problems in patients with SMA type 3a, older than 30 years of age, compared to younger patients of this SMA type.The Hammersmith Functional Motor Scale Expanded scores showed a negligible correlation with jaw and mastication problems, a low negative correlation with swallowing problems and a moderate negative correlation with intelligibility problems. Reduced mouth opening showed a significant, but low correlation with bulbar complaints in patients with SMA type 2.

CONCLUSIONS

Fatigue associated with mastication and swallowing problems were frequently reported complaints. Patients 30 years and older with milder forms of SMA showed an increase of self-reported bulbar problems.

Muscle strength and motor function throughout life in a cross-sectional cohort of 180 patients with spinal muscular atrophy types 1c-4

BACKGROUND AND PURPOSE

Natural history studies in spinal muscular atrophy (SMA) have primarily focused on infants and children. Natural history studies encompassing all age groups and SMA types are important for the interpretation of treatment effects of recently introduced survival motor neuron gene-augmenting therapies.

METHODS

We conducted a cross-sectional study to investigate muscle strength, Hammersmith Functional Motor Scale (Expanded) score and the patterns of muscle weakness in relation to age and SMA type.

RESULTS

We included 180 patients with SMA types 1-4 in the age range 1-77.5 years with median disease duration of 18 (range 0-65.8) years. With the exception of the early phases of disease in which children with SMA types 2 and 3 may achieve new motor skills and show a temporary increase in muscle strength, cross-sectional data suggested that declining muscle strength and loss of motor skills over time are characteristic of all SMA types. Mean loss of strength was at least 1 point on the Medical Research Council score and 0.5 point on the Hammersmith Functional Motor Scale (Expanded) score per year. Trend lines compatible with deterioration of motor function and muscle strength started in childhood and continued into adulthood. The age at loss of specific motor skills was associated with disease severity. Triceps, deltoid, iliopsoas and quadriceps were the weakest muscles in all patients. Hierarchical cluster analysis did not show a segmental distribution of muscle weakness as suggested previously.

CONCLUSIONS

Progressive muscle weakness and loss of motor function are characteristic of all SMA types and all ages.

Mapping metabolites from rough terrain: laser ablation electrospray ionization on non-flat samples

A laser ablation electrospray ionization (LAESI) source was custom-built to accommodate the topography of non-flat sample surfaces. Reproducible ablation mark diameters of 69 ± 7 μm in average have been achieved.

Correction: Mapping metabolites from rough terrain: laser ablation electrospray ionization on non-flat samples

Correction for ‘Mapping metabolites from rough terrain: laser ablation electrospray ionization on non-flat samples’ by Benjamin Bartels et al., RSC Adv., 2017, 7, 9045–9050.

Motility, Chemotaxis and Aerotaxis Contribute to Competitiveness during Bacterial Pellicle Biofilm Development

Biofilm formation is a complex process involving various signaling pathways and changes in gene expression. Many of the sensory mechanisms and regulatory cascades involved have been defined for biofilms formed by diverse organisms attached to solid surfaces. By comparison, our knowledge on the basic mechanisms underlying the formation of biofilms at air-liquid interfaces, that is, pellicles, is much less complete. In particular, the roles of flagella have been studied in multiple solid-surface biofilm models but remain largely undefined for pellicles. In this work, we characterize the contributions of flagellum-based motility, chemotaxis and oxygen sensing to pellicle formation in the Gram-positive Bacillus subtilis. We confirm that flagellum-based motility is involved in, but is not absolutely essential for, B. subtilis pellicle formation. Further, we show that flagellum-based motility, chemotaxis and oxygen sensing are important for successful competition during B. subtilis pellicle formation. We report that flagellum-based motility similarly contributes to pellicle formation and fitness in competition assays in the Gram-negative Pseudomonas aeruginosa. Time-lapse imaging of static liquid cultures demonstrates that, in both B. subtilis and P. aeruginosa, a turbulent flow forms in the tube and a zone of clearing appears below the air-liquid interface just before the formation of the pellicle but only in strains that have flagella.

Spatially resolved in vivo plant metabolomics by laser ablation-based mass spectrometry imaging (MSI) techniques: LDI-MSI and LAESI

This short review aims to summarize the current developments and applications of mass spectrometry-based methods for in situ profiling and imaging of plants with minimal or no sample pre-treatment or manipulation. Infrared-laser ablation electrospray ionization and UV-laser desorption/ionization methods are reviewed. The underlying mechanisms of the ionization techniques-namely, laser ablation of biological samples and electrospray ionization-as well as variations of the LAESI ion source for specific targets of interest are described.

Peptide methyl ketones as reversible inhibitors of cysteine proteinases

Peptide methyl ketones represent a new class of reversible, competitive cysteine proteinase inhibitor with little or no effect on serine proteinases. The affinity of the inhibitors to papain (EC 3.4.22.3), cathepsin B (EC 3.4.22.1) and cathepsin L (EC 3.4.22.15) depends on the peptide chain length and on side-chain effects. Variations in the P1 and P4 positions (terminology of Schechter and Berger) and their influence on the efficiency of the inhibitors have been investigated. The most effective inhibitors display inhibition constants in the micromolar range. In contrast to the endopeptidases papain and the cathepsins B and L, the aminoendopeptidase cathepsin H (EC 3.4.22.16) is not inhibited by N-acylated peptide methyl ketones but only by amino methyl ketones containing a free alpha-amino group. The endopeptidases are not affected by amino methyl ketones.

Regulation of the in vitro monoclonal immunoglobulin production in cultures of peripheral blood mononuclear cells and bone marrow cells from myeloma patients mediated by T cell dependent mitogens

In vitro monoclonal immunoglobulin (mIg) production of cultured tumour cells--prepared from the bone marrow (BM) or from the peripheral blood (PB) of 40 multiple myeloma (MM) patients, 16 patients with monoclonal gammopathy of undetermined significance and two patients with M. Waldenström--was measured with an enzyme-linked immunosorbent assay (ELISA) using anti-idiotype and anti-class specific antisera. After in vitro stimulation with pokeweed mitogen (PWM) or OKT3 antibody, mIg production was regularly suppressed in BM cell cultures, whereas enhanced, unaltered or suppressed production was observed in PB cell cultures. These observations show that the expanded clone in MM can still be regulated in vitro. Separation experiments demonstrated the involvement of T cells in this in vitro system. The results could be explained by the hypothesis that activated T cells can suppress mature cells of B cell differentiation, as found in BM of the patients, but stimulate earlier B cells from the peripheral blood towards differentiation into Ig secreting cells.

Cytostatic drug sensitivity test for human multiple myeloma, measuring monoclonal immunoglobulin produced by bone marrow cells in vitro

An in vitro cytostatic drug sensitivity test for human multiple myeloma has been developed, predicting differences in sensitivity of the individual tumor to various anticancer drugs. Bone marrow preparations containing the tumor cells were incubated with cytostatic drugs and cultured for 10 days. Using an enzyme-linked immunosorbent assay we measured tumor products--monoclonal immunoglobulin and beta 2-microglobulin--in the culture supernatants. The reduction of these products in vitro due to the drugs administered was compared with the patients' further clinical course during treatment with different standard cytostatic drug regimens. We found a predictive value of more than 80% for this easily performed test.

State as a determinant of infants' heart rate response to stimulation

With each infant serving as his own control, the data indicate that waking or sleeping states, independent of the prestimulation heart rate, can significantly affect the heart rate response to tactile stimulation.