The N-terminal ricin propeptide influences the fate of ricin A-chain in tobacco protoplasts.

The plant toxin ricin is synthesized in castor bean seeds as an endoplasmic reticulum (ER)-targeted precursor. Removal of the signal peptide generates proricin in which the mature A- and B-chains are joined by an intervening propeptide and a 9-residue propeptide persists at the N terminus. The two propeptides are ultimately removed in protein storage vacuoles, where ricin accumulates. Here we have demonstrated that the N-terminal propeptide of proricin acts as a nonspecific spacer to ensure efficient ER import and glycosylation. Indeed, when absent from the N terminus of ricin A-chain, the non-imported material remained tethered to the cytosolic face of the ER membrane, presumably by the signal peptide. This species appeared toxic to ribosomes. The propeptide does not, however, influence catalytic activity per se or the vacuolar targeting of proricin or the rate of retrotranslocation/degradation of A-chain in the cytosol. The likely implications of these findings to the survival of the toxin-producing tissue are discussed

The role of CDC48 in the retro-translocation of non-ubiquitinated toxin substrates in plant cells

When the catalytic A subunits of the castor bean toxins ricin and Ricinus communis agglutinin (denoted as RTA and RCA A, respectively) are delivered into the endoplasmic reticulum (ER) of tobacco protoplasts, they become substrates for ER-associated protein degradation (ERAD). As such, these orphan polypeptides are retro-translocated to the cytosol, where a significant proportion of each protein is degraded by proteasomes. Here we begin to characterise the ERAD pathway in plant cells, showing that retro-translocation of these lysine-deficient glycoproteins requires the ATPase activity of cytosolic CDC48. Lysine polyubiquitination is not obligatory for this step. We also show that while RCA A is found in a mannose-untrimmed form prior to its retro-translocation, a significant proportion of newly synthesised RTA cycles via the Golgi and becomes modified by downstream glycosylation enzymes. Despite these differences, both proteins are similarly retro-translocated

Influence of vitamin D supplementation on growth, body composition, pubertal development and spirometry in South African schoolchildren: A randomised controlled trial (ViDiKids)

Objective: To determine whether weekly oral vitamin D supplementation influences growth, body composition, pubertal development or spirometric outcomes in South African schoolchildren.   Design: Phase 3 double-blind randomised placebo-controlled trial.   Setting: Socioeconomically disadvantaged peri-urban district of Cape Town, South Africa.   Participants: 1682 children of black African ancestry attending government primary schools and aged 6-11 years at baseline.   Interventions: Oral vitamin D 3 (10 000 IU/week) versus placebo for 3 years.   Main outcome measures: Height-for-age and body mass index-for-age, measured in all participants; Tanner scores for pubertal development, spirometric lung volumes and body composition, measured in a subset of 450 children who additionally took part in a nested substudy.   Results: Mean serum 25-hydroxyvitamin D 3 concentration at 3-year follow-up was higher among children randomised to receive vitamin D versus placebo (104.3 vs 64.7 nmol/L, respectively; mean difference (MD) 39.7 nmol/L, 95% CI 37.6 to 41.9 nmol/L). No statistically significant differences in height-for-age z-score (adjusted MD (aMD) -0.08, 95% CI -0.19 to 0.03) or body mass index-for-age z-score (aMD -0.04, 95% CI -0.16 to 0.07) were seen between vitamin D versus placebo groups at follow-up. Among substudy participants, allocation to vitamin D versus placebo did not influence pubertal development scores, % predicted forced expiratory volume in 1 s (FEV1), % predicted forced vital capacity (FVC), % predicted FEV1/FVC, fat mass or fat-free mass.   Conclusions: Weekly oral administration of 10 000 IU vitamin D 3 boosted vitamin D status but did not influence growth, body composition, pubertal development or spirometric outcomes in South African schoolchildren. Trial registration numbers ClinicalTrials.gov NCT02880982, South African National Clinical Trials Register DOH-27-0916-5527

Influence of vitamin D supplementation on bone mineral content, bone turnover markers and fracture risk in South African schoolchildren: Multicentre double-blind randomised placebo-controlled trial (ViDiKids)

Randomised controlled trials (RCT) to determine the influence of vitamin D on bone mineral content (BMC) and fracture risk in children of Black African ancestry are lacking. We conducted a sub-study (n=450) nested within a Phase 3 RCT of weekly oral supplementation with 10,000 IU vitamin D3 vs. placebo for 3 years in HIV- uninfected Cape Town schoolchildren aged 6-11 years. Outcomes were BMC at the whole body less head (WBLH) and lumbar spine (LS) and serum 25-hydroxyvitamin D3 (25[OH]D3), parathyroid hormone (PTH), alkaline phosphatase, C-terminal telopeptide and procollagen type 1 N propeptide. Incidence of fractures was a secondary outcome of the main trial (n=1682). At baseline, mean serum 25(OH)D3 concentration was 70.0 nmol/L (s.d. 13.5), and 5.8% of participants had serum 25(OH)D3 concentrations <50 nmol/L. Among sub-study participants, end-trial serum 25(OH)D3 concentrations were higher for participants allocated to vitamin D vs. placebo (adjusted mean difference [aMD] 39.9 nmol/L, 95% CI 36.1 to 43.6) and serum PTH concentrations were lower (aMD -0.55 pmol/L, 95% CI -0.94 to -0.17). However, no interarm differences were seen for WBLH BMC (aMD -8.0 g, 95% CI - 30.7 to 14.7) or LS BMC (aMD -0.3 g, 95% CI -1.3 to 0.8) or serum concentrations of bone turnover markers. Fractures were rare among participants in the main trial randomised to vitamin D vs. placebo (7/755 vs. 10/758 attending at least one follow- up; adjusted odds ratio 0.70, 95% CI 0.27 to 1.85). In conclusion, a 3-year course of weekly oral vitamin D supplementation elevated serum 25(OH)D3 concentrations and suppressed serum PTH concentrations in HIV-uninfected South African schoolchildren of Black African ancestry but did not influence BMC or serum concentrations of bone turnover markers. Fracture incidence was low, limiting power to detect an effect of vitamin D on this outcome

Extraction and transport of sulfate using macrocyclic squaramide receptors

The selective extraction of the hydrophilic sulfate ion from water is highly challenging because the high free energy of hydration of this ion makes it more difficult to extract than less hydrophilic ions such as chloride and nitrate. Lipophilic macrocyclic squaramide receptors 1 and 2 were synthesized. Receptor 2 efficiently extracted sulfate from aqueous sodium sulfate solutions into a chloroform phase, via exchange with nitrate ions, overcoming the Hofmeister bias. The resulting 2$SO4 2� complex was readily recycled through precipitation of BaSO4. Transport of sulfate across a bulk chloroform membrane by 2 was demonstrated across a wide pH range (pH 3.2–9.4) and in the presence of high concentrations of competing anions (chloride, nitrate and dihydrogenphosphate), opening the door to the use of 2 for the selective removal of sulfate from water across a range of applications

Staying Active with Multimorbidity In Acute hospital settings (StAMInA) trial: protocol for a feasibility randomised controlled trial of allied health assistant mobility rehabilitation for patients with multimorbidity

Introduction Key to improving outcomes for patients with multimorbidity is increasing mobility through prescription of a physical activity programme, but this can be difficult to achieve in acute hospital settings. One approach that would assist physiotherapists to increase levels of physical activity is delegation of rehabilitation to allied health assistants. We aim to conduct a randomised controlled trial to determine the feasibility of an allied health assistant providing daily inpatient mobility rehabilitation for patients with multimorbidity.Methods and analysis Using a parallel group randomised controlled design, participants will be allocated to allied health assistant mobility rehabilitation or physiotherapist mobility rehabilitation. Adult inpatients (n=60) in an acute hospital with a diagnosis of multimorbidity who walked independently preadmission will be included. The experimental group will receive routine mobility rehabilitation, including daily mobilisation, from an allied health assistant under the supervision of a physiotherapist. The comparison group will receive routine rehabilitation from a physiotherapist. Feasibility will be determined using the following areas of focus in Bowen’s feasibility framework: Acceptability (patient satisfaction); demand (proportion of patients who participate); implementation (time allied health assistant/physiotherapist spends with participant, occasions of service); and practicality (cost, adverse events). Staff involved in the implementation of allied health assistant rehabilitation will be interviewed to explore their perspectives on feasibility. Secondary outcomes include: Physical activity (daily time spent walking); daily mobilisation (Y/N); discharge destination; hospital readmission; falls; functional activity (Modified Iowa Level of Assistance Scale); and length of stay. Descriptive statistics will be used to describe feasibility. Secondary outcomes will be compared between groups using Poisson or negative binomial regression, Cox proportional hazards regression, survival analysis, linear regression or logistic regression.Ethics and dissemination Ethics approval was obtained from Peninsula Health (HREC/97 431/PH-2023). Findings will be disseminated in peer-reviewed journals and conference presentations.Trial registration number Australian and New Zealand Clinical Trial Registry ACTRN12623000584639p