The genetic basis of multiple system atrophy

Multiple system atrophy (MSA) is a heterogenous, uniformly fatal neurodegenerative ɑ-synucleinopathy. Patients present with varying degrees of dysautonomia, parkinsonism, cerebellar dysfunction, and corticospinal degeneration. The underlying pathophysiology is postulated to arise from aberrant ɑ-synuclein deposition, mitochondrial dysfunction, oxidative stress and neuroinflammation. Although MSA is regarded as a primarily sporadic disease, there is a possible genetic component that is poorly understood. This review summarizes current literature on genetic risk factors and potential pathogenic genes and loci linked to both sporadic and familial MSA, and underlines the biological mechanisms that support the role of genetics in MSA. We discuss a broad range of genes that have been associated with MSA including genes related to Parkinson's disease (PD), oxidative stress, inflammation, and tandem gene repeat expansions, among several others. Furthermore, we highlight various genetic polymorphisms that modulate MSA risk, including complex gene-gene and gene-environment interactions, which influence the disease phenotype and have clinical significance in both presentation and prognosis. Deciphering the exact mechanism of how MSA can result from genetic aberrations in both experimental and clinical models will facilitate the identification of novel pathophysiologic clues, and pave the way for translational research into the development of disease-modifying therapeutic targets.

Linking autism spectrum disorders and parkinsonism: clinical and genetic association

BACKGROUND

Autism spectrum disorders (ASD) comprise many complex and clinically distinct neurodevelopmental conditions, with increasing evidence linking them to parkinsonism.

METHODS

We searched Medline and Embase from inception to 21 March 2022 and reviewed the bibliographies of relevant articles. Studies were screened and reviewed comprehensively by two independent authors.

RESULTS

Of 863 references from our search, we included eight clinical studies, nine genetic studies, and five case reports. Regardless of age group, Parkinson's disease (PD) and parkinsonian syndromes were more frequently observed in patients with ASD, though the evidence for increased rates of parkinsonism is less clear for children and adolescents. Parkinsonian features and hypokinetic behavior were common in Rett syndrome, with prevalence estimates ranging from 40% to 80%. Frequently observed parkinsonian features include bradykinesia, rigidity, hypomimia, and gait freezing. PD gene PARK2 copy number variations appear more frequently in ASD cases than controls. Evidence suggests that RIT2 and CD157/BST1 are implicated in ASD and PD, while the evidence for other PD-related genes (DRD2, GPCR37, the SLC gene family, and SMPD1) is less clear. Rare mutations, such as ATP13A2, CLN3, and WDR45, could result in autistic behavior and concomitant parkinsonism.

CONCLUSION

The prevalence of parkinsonism in ASD is substantially greater than in the general population or matched controls. Various PD-associated gene loci, especially PARK2, could confer susceptibility to ASD as well. Important future directions include conducting prospective cohort studies to understand how parkinsonian symptoms may progress, genetic studies to reveal relevant gene loci, and pathophysiologic studies to identify potential therapeutic targets.

Learning during the pandemic: Perspectives of medical students in Singapore

The COVID-19 pandemic has significantly disrupted medical education, particularly affecting clinical-year students. Educational institutions often had to halt, shorten or impose significant restrictions on their hospital rotations due to strict infection control and social-distancing guidelines implemented in tertiary healthcare institutions, as well as manpower and logistical constraints amid the pandemic. Thus, distance-based learning platforms such as online lectures and case-based teaching were increasingly adopted in place of bedside and face-to-face tutorials. While interactive virtual case-based discussions are generally useful in imparting clinical reasoning skills to medical students, they are unfortunately not able to fully replicate the experience of clerking, examining and managing real patients in the wards, which is a quintessential process towards building clinical acumen and attaining core clinical competencies. Therefore, for final year medical students who are preparing for their Bachelor of Medicine and Bachelor of Surgery (MBBS) examinations, many are naturally concerned by how learning in this "new normal" may affect their ability to make the transition to become competent junior doctors. As such, we seek to share our learning experiences as the first batch of medical students to have completed our entire final year of clinical education amid the COVID-19 pandemic, and offer 4 practical suggestions to future batches of students on how to adapt and optimise clinical learning under these circumstances: actively engaging in virtual learning, making the most of every clinical encounter, learning how to construct peer teaching/practice sessions, and maintaining physical and psychological well-being.

Abstract WP55: Good Collateral Status Predicts Better Outcomes in Endovascular Treatment of Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Introduction: Endovascular therapy (EVT) for the treatment of acute ischemic stroke in cervical and/or cerebral arterial occlusions is superior to standard medical therapy alone. This however requires careful patient selection and the current criteria utilising time windows and the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is imperfect, limiting its efficacy. We explore the impact of pretreatment collateral status (CS) in predicting EVT outcomes.

Methods: A systematic literature search was conducted on PubMed and EMBASE for randomized controlled trials and prospective and retrospective cohort studies without language restriction from January 01, 2000 to June 25, 2019. We included studies reporting efficacy and safety outcomes dichotomised by collateral status in patients with acute anterior circulation ischemic stroke that were treated with mechanical thrombectomy and/or intra-arterial thrombolysis. Odds ratios were pooled for good versus poor collaterals for outcomes based on a random-effects model.

Results: The search strategy yielded fifty-four (54) studies (n=7,599) (mean age 67.6 years; females 47.4%) for quantitative analysis, of which there were 2 pairs of studies with overlapping populations but had reported different outcomes. Thus, there were at least 7,441 unique individuals included in this analysis recruited between May 1992 and September 2018. Analysis showed that good CS was strongly associated with favourable functional outcomes (modified Rankin Scale 0-2) at discharge, as well as at 3 months or follow-up (Table 1). Good CS was also associated with higher revascularization rates, lower rates of mortality and lower rates of symptomatic intracranial hemorrhage.

Conclusions: Good pretreatment CS strongly predicts good functional outcome and lower complication rates. Pretreatment CS should be considered in the design of future clinical trials and as a selection criteria for EVT.

A systematic review and meta-regression analysis of nonoperative management of blunt traumatic thoracic aortic injury in 2897 patients

BACKGROUND

Thoracic endovascular aortic repair has transformed the management of blunt traumatic thoracic aortic injuries (BTTAI). Recent studies have suggested that the nonoperative management (NOM) of BTTAI may be a viable alternative. We investigated the NOM of BTTAI by conducting a systematic review and meta-analysis of the mortality proportions and incidence of complications.

METHODS

We searched PubMed through June 22, 2017, and referenced lists of included studies without language restriction, with the assistance of a trained librarian. We included studies that reported the NOM of BTTAI (≥5 participants). Two authors independently screened titles, abstracts, and performed data extraction. Pooled prevalence of mortality (aortic related, in hospital) were obtained based on binomial distribution with Freeman-Tukey double-arcsine transformation and continuity correction. The random-effects model was used for all analyses to account for variation between studies. Meta-regression was performed to explore sources of heterogeneity, including Injury Severity Score, age, and gender.

RESULTS

We included 35 studies comprising 2897 participants. The pooled prevalence of all-cause in-patient mortality in the overall, grade I, grade II, grade III, and grade IV populations are as follows: 29.0% (95% confidence interval [CI], 19.3%-39.6%; I² = 95%; P < .01), 6.8% (95% CI, 0.6%-19.3%; I² = 52%; P = .03), 0% (95% CI, 0%-2.0%; I² = 0%; P = .81), 29.2% (95% CI, 17%-42.5%; I² = 3%; P = .41), and 87.4% (95% CI, 16.4%-100%; I² = 48%; P = .14), respectively. The combined incidence of aortic-related in-patient mortality in the overall, grade I, grade II, and grade III populations are: 2.4% (95% CI, 0.4%-5.5%; I² = 60%; P < .01), 0.93% (95% CI, 0%-14.2%; I² = 65%; P < .01), 0% (95% CI, 0%-1.8%; I² = 0%; P = .99), and 0.13% (95% CI, 0%-6.4%; I² = 14%; P = .33), respectively. The total proportion of postdischarge aortic-related mortality is 0% (95% CI, 0%-0.5%; I² = 0%; P = .91). Meta-regression showed a decreased risk of in-hospital mortality as age increases (β = .99; 95% CI, 0.98-1.00), an increased risk of in-hospital mortality with a higher Injury Severity Score (β = 1.02; 95% CI, 1.00-1.04), and a decreased risk of in-hospital mortality among male patients (β = .54; 95% CI, 0.3-0.90).

CONCLUSIONS

This study provides, to our knowledge, the most up-to-date pooled estimate of mortality rates after the NOM of BTTAI. However, its interpretation is limited by the paucity of data and substantial quantitative heterogeneity. If patients are to be managed nonoperatively, we would recommend the judicious use of active surveillance in a select group of patients in the short, mid, and long term.

Introducing foreign DNA into tiger shrimp (Penaeus monodon) by electroporation

Electroporation was used to introduce pFLAG-CMV-1-BAP, a DNA fragment that includes a bacterial alkaline phosphatase gene driven by a human cytomegalovirus (CMV) promoter, into Penaeus monodon zygotes. The transgenic tiger shrimp was achievedby using 10kV, 28 pulses, 120 g sec pulse time, 10 cycles, and a DNA concentration of 37.5 microg/mL. The hatching rate of electroporated zygotes (46%) was significantly lower than that of zygotes in the untreated group (89%). The survival rate of postlarvae in the electroporated group using a DNA concentration of 37.5 microg/mL decreased from 0.6% for postlarva 45 to 0.4% for postlarva 120. Based on dot blot analysis, the rate of gene transfer was 37% in mysis-stage, 23% postlarva 15(PL15), 19% postlarva 45(PL45), and 21% 4-month-old (about PL120). Genomic Southern blotting demonstrated that DNA from transgenic tiger shrimp contained fragments of exogenous DNA that were smaller, larger and of the same molecular size as pFLAG-CMV-1-BAP. Transferred DNA fragments were integrated into the genomes of 31% of the transgenic tiger shrimp. The exogenous DNA was mosaically distributed in a wide variety of tissues. Immunohistochemical staining revealed that the FLAG-BAP fused-protein encoded by pFLAG-CMV-1-BAP was present in the ovaries of some transgenic tiger shrimp.

An experimental soft-release of oil-spill rehabilitated American coots (Fulica americana): II. Effects on health and blood parameters

The Unocal-Metrolink oil spill of 21 February 1995 resulted in approximately 7800 barrels of San Joaquin crude oil being deposited into the San Gabriel River in Huntington Beach, CA, USA. In order to determine long-term pathological effects of oil exposure and rehabilitation, hematological and serum biochemical parameters for both rehabilitated (RHB) American coots (Fulica americana) and reference (REF) coots were examined every 3-4 weeks (56, 81, 108 and 140 days post oil exposure) after birds were cleaned, rehabilitated and soft-released. Most significant differences in monthly comparisons between RHB and REF birds occurred 56 days following oil exposure. Total white blood cell (WBC) count, albumin:globulin (A:G) ratio and calcium concentration were higher in RHB birds compared to REF birds 56 days post oil exposure. In addition, mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase and creatine kinase activities, and creatinine, total protein (TP) and globulin concentrations were lower in RHB birds. Blood results from 56 days post oil exposure for RHB coots which subsequently died were compared to blood results from days 108 and 140 for REF coots which survived. Oiled and rehabilitated birds which died had significantly higher WBCs, packed cell volume, TP and globulin concentrations, and lower A:G ratio, MCH, MCHC, glucose and sodium concentrations compared to REF birds which survived. Blood result differences detected at 3-4-week intervals between RHB and REF survivors, and differences detected between RHB coots which died and REF coots which survived, suggested that RHB coots developed an inflammatory response (infectious or non-septic) and, concurrently, may have experienced decreased immune responsiveness. Additionally, RHB coots experienced either an iron (Fe) utilization or Fe metabolism problem. These pathophysiological mechanisms were consistent with increased hemosiderin (stored Fe) present in the liver, spleen and kidney of necropsied RHB birds, and may have contributed to RHB coot mortality. When blood parameter differences were examined for their impact on survival time, it was determined that RHB coots had shorter survival times if they had very high cholesterol (> or =449 mg/dl) or chloride (> or =110 MEQ/l) concentrations on day 56 post oil exposure. Interestingly, the lack of differences between RHB and REF coots from day 81 through day 140 suggested that, from a hematologic and clinical chemistry perspective, coots which were oiled, rehabilitated, released and survived at least 3.5 months could not be differentiated from wild (REF) coots. From these findings it appears that blood analysis, coupled with post-release survival data, may help discern reasons for increased mortality of oiled and rehabilitated birds, compared to non-oiled reference birds.