Dynamin-related protein 1 (Drp1) is the GTP-hydrolyzing mechanoenzyme that catalyzes mitochondrial fission in the cell. Residing in the cytosol as dimers and tetramers, Drp1 is recruited by receptors ...on the mitochondrial outer membrane, where it further assembles into a helical ring that drives division via GTP-dependent constriction. The Drp1 receptor Mff is a major regulator of mitochondrial fission, and its overexpression results in increased fission. In contrast, the alternative Drp1 receptors MiD51 and MiD49 appear to recruit inactive forms of Drp1, because their overexpression inhibits fission. Using genetic and biochemical assays, we studied the interaction of Drp1 with Mff. We show that the insert B region of Drp1 inhibits Mff-Drp1 interactions, such that recombinant Drp1 mutants lacking insert B form a stable complex with Mff. Mff cannot bind to assembly-deficient mutants of Drp1, suggesting that Mff selectively interacts with higher-order complexes of Drp1. In contrast, the alternative Drp1 receptors MiD51 and MiD49 can recruit Drp1 dimers. Therefore Drp1 recruitment by Mff versus MiD51 and MiD49 may result in different outcomes because they recruit different subpopulations of Drp1 from the cytosol.
Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which has been characterized by fever, respiratory, and gastrointestinal ...symptoms as well as shedding of virus RNA into feces. We performed a systematic review and meta-analysis of published gastrointestinal symptoms and detection of virus in stool and also summarized data from a cohort of patients with COVID-19 in Hong Kong.
We collected data from the cohort of patients with COVID-19 in Hong Kong (N = 59; diagnosis from February 2 through February 29, 2020),and searched PubMed, Embase, Cochrane, and 3 Chinese databases through March 11, 2020, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We analyzed pooled data on the prevalence of overall and individual gastrointestinal symptoms (loss of appetite, nausea, vomiting, diarrhea, and abdominal pain or discomfort) using a random effects model.
Among the 59 patients with COVID-19 in Hong Kong, 15 patients (25.4%) had gastrointestinal symptoms, and 9 patients (15.3%) had stool that tested positive for virus RNA. Stool viral RNA was detected in 38.5% and 8.7% among those with and without diarrhea, respectively (P = .02). The median fecal viral load was 5.1 log10 copies per milliliter in patients with diarrhea vs 3.9 log10 copies per milliliter in patients without diarrhea (P = .06). In a meta-analysis of 60 studies comprising 4243 patients, the pooled prevalence of all gastrointestinal symptoms was 17.6% (95% confidence interval CI, 12.3–24.5); 11.8% of patients with nonsevere COVID-19 had gastrointestinal symptoms (95% CI, 4.1–29.1), and 17.1% of patients with severe COVID-19 had gastrointestinal symptoms (95% CI, 6.9–36.7). In the meta-analysis, the pooled prevalence of stool samples that were positive for virus RNA was 48.1% (95% CI, 38.3–57.9); of these samples, 70.3% of those collected after loss of virus from respiratory specimens tested positive for the virus (95% CI, 49.6–85.1).
In an analysis of data from the Hong Kong cohort of patients with COVID-19 and a meta-analysis of findings from publications, we found that 17.6% of patients with COVID-19 had gastrointestinal symptoms. Virus RNA was detected in stool samples from 48.1% patients, even in stool collected after respiratory samples had negative test results. Health care workers should therefore exercise caution in collecting fecal samples or performing endoscopic procedures in patients with COVID-19, even during patient recovery.
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Purpose
Pelvic incidence (PI) is a position independent parameter used to quantify spinopelvic sagittal balance. PI is generally measured on lateral radiographs, but more recent studies have ...suggested better accuracy with standard CT scans versus three-dimensional (3D) CT scans. This study compares PI obtained from lateral XR, standard CT scan and CT scan with 3D reconstruction.
Methods
A total of 77 subjects with lateral XRs of the pelvis or lumbosacral spine and CT scans of the pelvis were randomly selected. Pelvic incidence on lateral XRs, standard CT scans and CT scans utilizing multiplanar reconstruction were measured and compared using intraclass correlation coefficients (ICC). PI was also measured on serial images in 28 individuals using the same imaging modality within 3 years and evaluated using ICC.
Results
Mean ± SD of PI measurements on XR, standard CT and CT with 3D reconstruction were 56° ± 13°, 53° ± 12° and 53° ± 12°, respectively, demonstrating a small but significant elevation of PI measurement on XR (
P
< 0.001). ICC values demonstrated a higher correlation between standard CT and 3D CT (ICC 0.986), compared to XR and standard CT (ICC 0.934) and XR and 3D CT (ICC 0.937). PI measurements on repeated imaging of the same individual also demonstrated that both CT methods produced more consistent measurements (ICC 0.986 for standard CT, 0.981 for 3D CT, 0.935 for XR).
Conclusion
Although standard XR does provide a high level of reliability, it appears to slightly overestimate PI. CT scans do provide increased reliability, with no additional benefit of 3D reconstructions over standard CT.
Humans are one of the few species undergoing an adolescent growth spurt. Because children enter the spurt at different ages making age a poor maturity measure, longitudinal studies are necessary to ...identify the growth patterns and identify commonalities in adolescent growth. The standard maturity determinant, peak height velocity (PHV) timing, is difficult to estimate in individuals due to diurnal, postural, and measurement variation. Using prospective longitudinal populations of healthy children from two North American populations, we compared the timing of the adolescent growth spurt's peak height velocity to normalized heights and hand skeletal maturity radiographs. We found that in healthy children, the adolescent growth spurt is standardized at 90% of final height with similar patterns for children of both sexes beginning at the initiation of the growth spurt. Once children enter the growth spurt, their growth pattern is consistent between children with peak growth at 90% of final height and skeletal maturity closely reflecting growth remaining. This ability to use 90% of final height as easily identified important maturity standard with its close relationship to skeletal maturity represents a significant advance allowing accurate prediction of future growth for individual children and accurate maturity comparisons for future studies of children's growth.
Purpose To investigate the relation between cam, acetabular version, and pelvic incidence. Methods This was a retrospective analysis of 65 patients with symptomatic hip pain and radiographic signs of ...femoroacetabular impingement (FAI). Twenty-seven patients were used as a control. All patients received a CT scan of the pelvis that included the sacral endplate. Alpha angle, acetabular version, and pelvic incidence (PI) were measured on 2D CT. Patients were then assigned to one of four groups: control, cam (alpha angle > 55°, version > 15°), retroverted (alpha angle < 55°, version < 15°), or mixed (alpha angle > 55°, version < 15°). Results The PI in mixed-type FAI was 46.7° ± 3.7°, which showed a statistically significant decrease from the PI of the control group, 56.1° ± 4.4° ( P = .01). The PI for cam-only deformity was 50.8° ± 4.6°, and the PI for retroverted-only deformity was 51.0° ± 4.6°. Neither was statistically different from the control. Conclusions This study suggests that mixed-type FAI may develop as a response to decreased PI. This result is consistent with previous reports showing decreased PI associated with cam and retroversion deformities. Although the cause of FAI remains controversial, the potential impact of sagittal balance of the pelvis, and specifically, decreased PI, should not be ignored. Level of Evidence Level IV, therapeutic case series.
Rising health care expenditures and the adoption of bundled-care initiatives require efficient resource allocation for shoulder arthroplasty. To determine a reliable and accessible metric for ...implementing perioperative care pathways, we compared the accuracy of the Elixhauser Comorbidity Measure (ECM) and Charlson Comorbidity Index (CCI) for predicting adverse events and postoperative discharge destination after shoulder arthroplasty.
The National Inpatient Sample was queried for patients who underwent total shoulder arthroplasty or reverse total shoulder arthroplasty between 2002 and 2014. Logistic regression models were constructed with basic demographic variables and either the ECM or the CCI to predict inpatient deaths, complications, extended length of stay, and discharge disposition. The predictive discrimination of each model was evaluated using the concordance statistic (C-statistic).
We identified a total of 90,491 patients. The model incorporating both basic demographic variables and the complete set of ECM comorbidity variables provided the best predictive model, with a C-statistic of 0.867 for death, 0.752 for extended length of stay, and 0.81 for nonroutine discharge. The model's discrimination for postoperative complications was good, with C-statistics ranging from 0.641 to 0.879.
A predictive model using the ECM outperforms models using the CCI for anticipating resource utilization following shoulder arthroplasty. Our results may assist value-based reimbursement methods to promote quality of care and reduce health care expenditures.
The proximal humerus ossification system (PHOS), olecranon apophyseal ossification system (OAOS), and modified Fels wrist skeletal maturity system (mFWS) were recently developed or updated using a ...historical, mostly White, pediatric population. These upper extremity skeletal maturity systems have demonstrated skeletal age estimation performance superior or equivalent to Greulich and Pyle in historical patients. Their applicability to modern pediatric populations has not yet been evaluated.
We reviewed anteroposterior shoulder, lateral elbow, and anteroposterior hand and wrist x-rays of 4 pediatric cohorts: White males, Black males, White females, and Black females. Peripubertal x-rays were evaluated: males 9 to17 years and females 7 to 15 years. Five nonpathologic radiographs for each age and joint were randomly selected from each group. Skeletal age estimates made by each of the 3 skeletal maturity systems were plotted against the chronological age associated with each radiograph and compared between cohorts, and with the historical patients.
Five hundred forty modern radiographs were evaluated (180 shoulders, 180 elbows, and 180 wrists). All radiographic parameters had inter- and intra-rater reliability coefficients at or above 0.79, indicating very good reliability. For PHOS, White males had delayed skeletal age compared with Black males (Δ-0.12 y, P =0.02) and historical males (Δ-0.17 y, P <0.001). Black females were skeletally advanced compared with historical females (Δ0.11 y, P =0.01). For OAOS, White males (Δ-0.31 y, P <0.001) and Black males (Δ-0.24 y, P <0.001) had delayed skeletal age compared with historical males. For mFWS, White males (Δ0.29 y, P =0.024), Black males (Δ0.58 y, P <0.001), and Black females (Δ0.44 y, P <0.001) had advanced skeletal age compared with historical counterparts of the same sex. All other comparisons were not significant ( P >0.05).
The PHOS, OAOS, and mFWS have mild discrepancies in skeletal age estimates when applied to modern pediatric populations depending on the race and sex of the patient.
Level III - retrospective chart review.
The Modified Fels Wrist system is potentially the most accurate clinically accessible skeletal maturity system utilizing hand or wrist radiographs. During development, parameters distal to the ...metacarpals were excluded. We attempted to further optimize the Modified Fels wrist system through the inclusion of hand parameters distal to the metacarpals.
Forty-three new anteroposterior (AP) hand radiographic parameters were identified from the Fels and Greulich and Pyle (GP) skeletal maturity systems. Twelve parameters were eliminated from further evaluation for poor correlation with skeletal maturity, poor reliability, and lack of relevance in the peripubertal years. In addition to the 8 previously described Modified Fels Wrist parameters, 31 hand radiographic parameters were evaluated on serial peripubertal AP hand radiographs to identify the ones most important for accurately estimating skeletal age. This process produced a "Modified Fels hand-wrist" model; its performance was compared with (1) GP only; (2) Sanders Hand (SH) only; (3) age, sex, and GP; (4) age, sex, and SH; and (5) Modified Fels Wrist system.
Three hundred seventy-two radiographs from 42 girls and 38 boys were included. Of the 39 radiographic parameters that underwent full evaluation, 9 remained in the combined Modified Fels Hand-Wrist system in addition to chronological age and sex. Four parameters are wrist specific, and the remaining 5 are hand specific. The Hand-Wrist system outperformed both GP and SH in estimating skeletal maturity ( P <0.001). When compared with the Modified Fels Wrist system, the Modified Fels Hand-Wrist system performed similarly regarding skeletal maturity estimation (0.36±0.32 vs. 0.34±0.26, P =0.59) but had an increased (worse) rate of outlier predictions >1 year discrepant from true skeletal maturity (4.9% vs. 1.9%, P =0.01).
The addition of hand parameters to the existing Modified Fels Wrist system did not improve skeletal maturity estimation accuracy and worsened the rate of outlier estimations. When an AP hand-wrist radiograph is available, the existing Modified Fels wrist system is best for skeletal maturity estimation.
Level III.
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