Investigation of Electrical Transitions in the First Steps of Spark Plasma Sintering: Effects of Pre-Oxidation and Mechanical Loading within Copper Granular Media

Spark Plasma Sintering (SPS) has become a conventional and promising sintering method for powder consolidation. This study aims to well understand the mechanisms of densification encountered during SPS treatments, especially in the early stages of sintering. The direct current (DC) electrical behavior of copper granular medium is characterized. Their properties are correlated with their microstructural evolutions through post-mortem scanning electron microscope (SEM) observations to allow a thorough understanding of the involved Branly effect that is suspected to occur in SPS. The electrical response is studied by modifying the initial thickness of the oxide layer on particles surfaces and applying various mechanical loads on the granular medium. Without load and at low current, the measured quasi-reversible behavior is connected to the formation of spots at the microcontacts between the particles. By increasing the current, the Branly transition from an insulating to a conductive state suddenly occurs. The insulating oxide layer is destroyed, and micro-bridges are created. The application of a mechanical pressure strongly modifies the DC Branly effect. Increasing low stress leads to a strong decrease in the breakdown field. For high-applied pressure, successive drops in the electric field are detected during the electrical transition. These successive drops are induced by microcracking of the insulating oxide layer.     

Inhibition of In Vitro TNF-α Production by Anisomeles malabarica R.Br. Reinforces Its Anti-Rheumatic and Immunomodulatory Properties

In-vivo studies have suggested the anti-rheumatic and immunomodulatory properties of the methanolic extract of the plant Anisomeles malabarica R.Br. However, the mechanism of action of this plant in the modulation of inflammation using the various in vitro models has not been explored earlier. Hence, the current investigation was undertaken to study the anti-rheumatic and immunomodulatory role of aerial parts, leaves and roots in lipopolysaccharide (LPS) mediated signaling in macrophage and mouse connective tissue cell cultures. It was observed from the present study that by employing tumor necrosis factor-α (TNF-α) bioassay, all the three extracts viz., aerial parts, leaves and roots inhibited TNF-α production in LPS (1 μg/mL) stimulated RAW-32 cells. 38.75 % inhibition of TNF-α was observed at 200 μg extracts of the aerial parts of the plant followed by 17.64 and 14.94 % by the roots and leaves respectively. Taken together, these findings from the present in vitro studies suggest the anti-rheumatic and immunomodulatory properties of the methanolic extracts of A. malabarica.     

Functional outcomes of nonunion scaphoid fracture treated by pronator quadratus pedicled bone graft

Between 1998 and 2007, a pronator quadratus pedicled bone graft was performed for 45 patients of ununited scaphoid fracture. One of them had bilateral ununited scaphoid fracture. There were 29 men and 16 women with a median age at operation of 24 (16-32) years. The affected side was the right side (dominant hand) in 32 patients whereas 13 patients had fracture of the nondominant left side. There had been 32 proximal pseudoarthrosis (through or proximal to the junction of the proximal and middle thirds of the bone) and 14 of the middle third of the scaphoid. The original fractures were caused by motor cycle accidents in 23 patients, falling on outstretched hand in 15 patients, and sport injuries in the remaining 7 patients. Surgery was indicated from 5 months to 6 years after injury (average 43 months) because of complaints of pain on heavy work. The fracture has been missed at the initial examination in 23 patients whereas cast immobilization was done for 6 weeks and 3 months in 15 and 7 cases, respectively, that had failed to result in union. There were no preoperative osteoarthritic changes, but in 25 cases, there were avascular necrosis of the proximal fragment of the scaphoid. Forty-three patients showed radiographic union after an average of 14 weeks (12-16 weeks). One patient had dislodgement of the graft and refused to do it again. The average range of movement of wrist improved after operation. Taken as a percentage of the normal range, dorsiflexion increased from 69% to 80%, palmar flexion from 66% to 76%, radial deviation from 45% to 70%, and ulnar deviation from 67% to 84%. Grip strength improved from 82% to 92% of normal. All the patients have been able to return to their former activities with no pain.     

COVID-19 vaccine effectiveness by HIV status and history of injection drug use: a test-negative analysis

Introduction

People living with HIV (PLWH) and/or who inject drugs may experience lower vaccine effectiveness (VE) against SARS-CoV-2 infection.

Methods

A validated algorithm was applied to population-based, linked administrative datasets in the British Columbia COVID-19 Cohort (BCC19C) to ascertain HIV status and create a population of PLWH and matched HIV-negative individuals. The study population was limited to individuals who received an RT-PCR laboratory test for SARS-CoV-2 between 15 December 2020 and 21 November 2021 in BC, Canada. Any history of injection drug use (IDU) was ascertained using a validated administrative algorithm. We used a test-negative study design (modified case−control analysis) and multivariable logistic regression to estimate adjusted VE by HIV status and history of IDU.

Results

Our analysis included 2700 PLWH and a matched population of 375,043 HIV-negative individuals, among whom there were 351 and 103,049 SARS-CoV-2 cases, respectively. The proportion of people with IDU history was much higher among PLWH compared to HIV-negative individuals (40.7% vs. 4.3%). Overall VE during the first 6 months after second dose was lower among PLWH with IDU history (65.8%, 95% CI = 43.5–79.3) than PLWH with no IDU history (80.3%, 95% CI = 62.7–89.6), and VE was particularly low at 4–6 months (42.4%, 95% CI = −17.8 to 71.8 with IDU history vs. 64.0%; 95% CI = 15.7–84.7 without), although confidence intervals were wide. In contrast, overall VE was 88.6% (95% CI = 88.2–89.0) in the matched HIV-negative population with no history of IDU and remained relatively high at 4–6 months after second dose (84.6%, 95% CI = 83.8–85.4). Despite different patterns of vaccine protection by HIV status and IDU history, peak estimates were similar (≥88%) across all populations.

Conclusions

PLWH with a history of IDU may experience lower VE against COVID-19 infection, although findings were limited by a small sample size. The lower VE at 4–6 months may have implications for booster dose prioritization for PLWH and people who inject drugs. The immunocompromising effect of HIV, substance use and/or co-occurring comorbidities may partly explain these findings.     

Radio Frequency Ablation and Pulsed Radiofrequency for Treating Peripheral Neuralgias

Purpose of Review

Peripheral nerve pain is common among patients with typical management including the use of pain medications, neuropathic agents, steroid injections, and nerve blocks. Additionally, the use of pulsed radiofrequency (PRF) and radiofrequency ablation (RFA) can be used in the management of chronic peripheral nerve pain. Previous studies investigating the effectiveness of RFA and PRF, typically case reports, have demonstrated that peripheral nerve RFA and PRF have the potential to provide relief of chronic pain for long duration. Our study aimed at testing efficacy of RFA/PRF for treating peripheral neuralgia. This was a retrospective review. We identified 16 patients who received 17 RFAs/PRFs. Outcomes of interest collected included pain scores before and after procedures, percent improvement in pain after each procedure, and duration of improvement until the time of data collection. In addition, demographic data including age, sex, and nerves involved were collected.

Recent Findings

Eleven patients (12 RFAs/PRFs) (80%) reported improvement after their procedure. Pain scores improved significantly from 6.3?±?2.3 before each procedure to 3.6?±?2.7 after each procedure (p?=?0.003). Eleven patients (12 RFAs/PRFs) reported an average improvement of 60.8%?±?35% after their procedure with an average duration of improvement of 128.8?±?106.8 days.

Summary

RFA and PRF can be used to treat chronic peripheral pain after conservative methods fail to do so. Large clinical trials are needed to confirm our finding.

     

In-Room Ultraviolet Air Filtration Units Reduce Airborne Particles During Total Joint Arthroplasty

Reducing airborne bioburden in total joint arthroplasty (TJA) is of critical importance. The efficacy of crystalline ultraviolet-C (C-UVC) filtration in reducing bioburden in a dynamic operating room (OR) environment has not been evaluated. We assessed whether C-UVC filtration reduced (i) total particle counts (TPC); (ii) viable particle counts (VPC); and (iii) colony-forming units (CFUs). Fifty primary TJA cases were performed in a positive-pressure OR; 25 cases with the C-UVC unit and 25 cases without. The air was sampled by a particle counter and an impact air sampler to measure particle counts and CFUs, respectively. To compare TPC, VPC, and CFU/m³ between groups, independent t tests and multivariate regression, adjusted for number of OR staff and door openings, were performed. The C-UVC group had significantly lower TPC (2.6 × 10⁶ vs. 4.7 × 10⁶ particles, p = 0.001) and VPC (18,605 vs. 27,516 particles, p = 0.001). There were fewer CFUs in the C-UVC group (10.9 CFU/m³ vs. 13.7 CFU/m³, p = 0.163). Multivariate analysis identified C-UVC filtration as a significant predictor of decreased TPC (β = −0.44, p = 0.002) and VPC (β = −0.47, p = 0.001) after accounting for door openings and number of OR staff. The reduction in CFUs was not significant on multivariate analysis. In this prospective pilot study, a C-UVC air disinfection and recirculation unit led to a significant reduction in both TPC and VPC and a non-significant reduction in CFU. Statement of clinical significance: Further studies are needed to investigate the effects of C-UVC filtration units on surgical-site infection rates. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:431-437, 2020     

Effect of purslane seed supplementation on inflammatory cytokines,oxidative stress and muscle damage in response to high-intensity intermittent exercise in national athlete runners

Sport Sciences for Health - Purslane supplementation has anti-oxidative, anti-inflammatory, skeletal muscle-relaxant activities. However, it is unknown if the ingestion of purslane will affect the...