Pluripotent stem cell derived dopaminergic subpopulations model the selective neuron degeneration in Parkinson's disease

In Parkinson’s disease (PD), substantia nigra (SN) dopaminergic (DA) neurons degenerate, while related ventral tegmental area (VTA) DA neurons remain relatively unaffected. Here, we present a methodology that directs the differentiation of mouse and human pluripotent stem cells toward either SN- or VTA-like DA lineage and models their distinct vulnerabilities. We show that the level of WNT activity is critical for the induction of the SN- and VTA-lineage transcription factors Sox6 and Otx2, respectively. Both WNT signaling modulation and forced expression of these transcription factors can drive DA neurons toward the SN- or VTA-like fate. Importantly, the SN-like lineage enriched DA cultures recapitulate the selective sensitivity to mitochondrial toxins as observed in PD, while VTA-like neuron-enriched cultures are more resistant. Furthermore, a proteomics approach led to the identification of compounds that alter SN neuronal survival, demonstrating the utility of our strategy for disease modeling and drug discovery.

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Derivation of distinct dopaminergic subpopulations from pluripotent stem cells

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Wnt signaling inhibitors promote SN dopaminergic neuron specification

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Modeling selective vulnerability of SN dopaminergic neurons in vitro

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Proteomics reveals pathways that promote SN dopaminergic neuron survival

Transversus abdominis release (TAR) for ventral hernia repair: open or robotic? Short-term outcomes from a systematic review with meta-analysis

PURPOSE

To compare early postoperative outcomes after transversus abdominis release (TAR) for ventral hernia repair with open (oTAR) and robotic (rTAR) approach.

METHODS

A systematic search of PubMed/MEDLINE, EMBASE, SCOPUS and Web of Science databases was conducted to identify comparative studies until October 2020. A meta-analysis of postoperative short-term outcomes was performed including complications rate, operative time, length of stay, surgical site infection (SSI), surgical site occurrence (SSO), SSO requiring intervention (SSOPI), systemic complications, readmission, and reoperation rates as measure outcomes.

RESULTS

Six retrospective studies were included in the analysis with a total of 831 patients who underwent rTAR (n = 237) and oTAR (n = 594). Robotic TAR was associated with lower risk of complications rate (9.3 vs 20.7%, OR 0.358, 95% CI 0.218-0.589, p < 0.001), lower risk of developing SSO (5.3 vs 11.5%, OR 0.669, 95% CI 0.307-1.458, p = 0.02), lower risk of developing systemic complications (6.3 vs 26.5%, OR 0.208, 95% CI 0.100-0.433, p < 0.001), shorter hospital stay (SMD - 4.409, 95% CI - 6.000 to - 2.818, p < 0.001) but longer operative time (SMD 53.115, 95% CI 30.236-75.993, p < 0.01) compared with oTAR. There was no statistically significant difference in terms of SSI, SSOPI, readmission, and reoperation rates.

CONCLUSION

Robotic TAR improves recovery by adding the benefits of minimally invasive procedures when compared to open surgery. Although postoperative complications appear to decrease with a robotic approach, further studies are needed to support the real long-term and cost-effective advantages.

Volatile organic compounds in a headspace sampling system and asthmatics sputum samples

Background:The headspace of a biological sample contains exogenous VOCs present within the sampling environment which represent the background signal.Study aims:This study aimed to characterise the background signal generated from a headspace sampling system in a clinical site, to evaluate intra- and inter-day variation of background VOC and to understand the impact of a sample itself upon commonly reported background VOC using sputum headspace samples from severe asthmatics.Methods:The headspace, in absence of a biological sample, was collected hourly from 11am to 3pm within a day (time of clinical samples acquisition), and from Monday to Friday in a week, and analysed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Chemometric analysis identified 1120 features, 37 of which were present in at least the 80% of all the samples. The analyses of intra- and inter-day background variations were performed on thirteen of the most abundant features, ubiquitously present in headspace samples. The concentration ratios relative to background were reported for the selected abundant VOC in 36 asthmatic sputum samples, acquired from 36 stable severe asthma patients recruited at Glenfield Hospital, Leicester, UK.Results:The results identified no significant intra- or inter-day variations in compounds levels and no systematic bias of z-scores, with the exclusion of benzothiazole, whose abundance increased linearly between 11am and 3pm with a maximal intra-day fold change of 2.13. Many of the identified background features are reported in literature as components of headspace of biological samples and are considered potential biomarkers for several diseases. The selected background features were identified in headspace of all severe asthma sputum samples, albeit with varying levels of enrichment relative to background.Conclusion:Our observations support the need to consider the background signal derived from the headspace sampling system when developing and validating headspace biomarker signatures using clinical samples.

Liposome-Embedding Silicon Microparticle for Oxaliplatin Delivery in Tumor Chemotherapy

Mesoporous silicon microparticles (MSMPs) can incorporate drug-carrying nanoparticles (NPs) into their pores. An NP-loaded MSMP is a multistage vector (MSV) that forms a Matryoshka-like structure that protects the therapeutic cargo from degradation and prevents its dilution in the circulation during delivery to tumor cells. We developed an MSV constituted by 1 µm discoidal MSMPs embedded with PEGylated liposomes containing oxaliplatin (oxa) which is a therapeutic agent for colorectal cancer (CRC). To obtain extra-small liposomes able to fit the 60 nm pores of MSMP, we tested several liposomal formulations, and identified two optimal compositions, with a prevalence of the rigid lipid 1,2-distearoyl-sn-glycero-3-phosphocholine and of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]. To improve the MSV assembly, we optimized the liposome-loading inside the MSMP and achieved a five-fold increase of the payload using an innovative lyophilization approach. This procedure also increased the load and limited dimensional changes of the liposomes released from the MSV in vitro. Lastly, we found that the cytotoxic efficacy of oxa-loaded liposomes and-oxa-liposome-MSV in CRC cell culture was similar to that of free oxa. This study increases knowledge about extra-small liposomes and their loading into porous materials and provides useful hints about alternative strategies for designing drug-encapsulating NPs.

Efficacy of transversus abdominis plane (TAP) block in colorectal surgery: a systematic review and meta-analysis

BACKGROUND

Multimodal opioid-sparing analgesia is a key component of the enhanced recovery after surgery (ERAS) protocol for postoperative pain management. Transversus abdominis plane (TAP) block has contributed to the implementation of this approach in different kinds of surgical procedures. The aim of this study was to evaluate the efficacy of TAP block and its impact on recovery in colorectal surgery.

METHODS

A comprehensive literature search of the PubMed, Embase, and Scopus databases was conducted. Studies that compared TAP block to a control group (no TAP block or placebo) after colorectal resections were included. The effects of TAP block in patients undergoing colorectal surgery were assessed, including the technical aspects of the procedure. Two measures were used to evaluate the effectiveness of postoperative pain control: a numeric pain rating score at rest and on coughing or movement at 24 h following surgery and the opioid requirement at 24 h. Clinical aspects of recovery were postoperative ileus, surgical site infection, postoperative nausea and vomiting, and length of hospital stay.

RESULTS

Sixteen studies were included in the analysis. Data showed that TAP block is a safe procedure associated with a significant reduction in the pain score at rest [WMD - 0.91 (95% CI - 1.56; - 0.27); p < 0.05] and on coughing or movement [WMD - 0.36 (95% CI - 0.72; - 0.01); p < 0.05] at 24 h after surgery and a significant decrease in morphine consumption in the TAP block group the day after surgery [WMD - 2.07 (95% CI - 2.63; - 1.51); p < 0.001].

CONCLUSIONS

TAP block appears to provide both an effective analgesia and a significant reduction in opioid use on the first postoperative day after colorectal surgery. Its use does not seem to lead to increased postoperative complications.

Assessment of breath volatile organic compounds in acute cardiorespiratory breathlessness: a protocol describing a prospective real-world observational study

INTRODUCTION

Patients presenting with acute undifferentiated breathlessness are commonly encountered in admissions units across the UK. Existing blood biomarkers have clinical utility in distinguishing patients with single organ pathologies but have poor discriminatory power in multifactorial presentations. Evaluation of volatile organic compounds (VOCs) in exhaled breath offers the potential to develop biomarkers of disease states that underpin acute cardiorespiratory breathlessness, owing to their proximity to the cardiorespiratory system. To date, there has been no systematic evaluation of VOC in acute cardiorespiratory breathlessness. The proposed study will seek to use both offline and online VOC technologies to evaluate the predictive value of VOC in identifying common conditions that present with acute cardiorespiratory breathlessness.

METHODS AND ANALYSIS

A prospective real-world observational study carried out across three acute admissions units within Leicestershire. Participants with self-reported acute breathlessness, with a confirmed primary diagnosis of either acute heart failure, community-acquired pneumonia and acute exacerbation of asthma or chronic obstructive pulmonary disease will be recruited within 24 hours of admission. Additionally, school-age children admitted with severe asthma will be evaluated. All participants will undergo breath sampling on admission and on recovery following discharge. A range of online technologies including: proton transfer reaction mass spectrometry, gas chromatography ion mobility spectrometry, atmospheric pressure chemical ionisation-mass spectrometry and offline technologies including gas chromatography mass spectroscopy and comprehensive two-dimensional gas chromatography-mass spectrometry will be used for VOC discovery and replication. For offline technologies, a standardised CE-marked breath sampling device (ReCIVA) will be used. All recruited participants will be characterised using existing blood biomarkers including C reactive protein, brain-derived natriuretic peptide, troponin-I and blood eosinophil levels and further evaluated using a range of standardised questionnaires, lung function testing, sputum cell counts and other diagnostic tests pertinent to acute disease.

ETHICS AND DISSEMINATION

The National Research Ethics Service Committee East Midlands has approved the study protocol (REC number: 16/LO/1747). Integrated Research Approval System (IRAS) 198921. Findings will be presented at academic conferences and published in peer-reviewed scientific journals. Dissemination will be facilitated via a partnership with the East Midlands Academic Health Sciences Network and via interaction with all UK-funded Medical Research Council and Engineering and Physical Sciences Research Council molecular pathology nodes.

TRIAL REGISTRATION NUMBER

NCT03672994.