Scar Size Research Articles

Contact size and debris ejection in fretting: The inappropriate use of Archard-type analysis of wear data and the development of alternative wear equations for commonly employed non-conforming specimen pair geometries

It has been long understood that fretting differs from sliding wear in that the relative displacement between the bodies is generally smaller than the size of the contact between them, with debris ejection from the contact thus playing an important role in the behaviour of the contact in fretting. Whilst these ideas were clearly articulated more than 30 years ago via Godet's third-body approach and Berthier's concept of the tribology circuit, calculation of wear rates in fretting have continued to employ Archard's wear equation (or approaches directly derived from it), despite this approach assuming that the rate of wear is controlled by the rate of generation of wear debris (as opposed to the rate of its ejection from the contact). It has been shown recently that when debris ejection is the rate-determining-process in fretting, the instantaneous rate of wear is inversely proportional to a characteristic dimension of the wear scar. When non-conforming specimen pair geometries (such as cylinder-on-flat) are employed in fretting testing, the wear scar size increases as wear proceeds, and thus the instantaneous rate of wear decreases. In this paper, wear equations have been derived for three commonly employed non-conforming pair specimen geometries, which all take the form Vw=KRn−1Edn (Vw is the wear scar volume, R is the radius of the non-plane specimen(s) in the pair and Ed is the frictional energy dissipated) where n varies between 0.67 and 0.8 depending upon the geometry and assumptions made regarding the governing equation. It is argued that the assumptions upon which the analysis is based are most valid for the cylinder-on-flat contact configuration with fretting perpendicular to the cylinder axis where the length of the line contact is large compared to the wear scar width. It is demonstrated that, despite the often apparently good fit of experimental data to an Archard-type equation, it is not appropriate to employ such Archard-type approaches to the analysis of fretting data in situations where debris ejection is the rate-determining-process. The equations derived in this paper relating wear scar size to some measure of the duration of the test should be used for such analysis instead of the linear relationships generally employed in previous work.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ЧАСТОТЫ И СТРУКТУРЫ ОСЛОЖНЕНИЙ НА ПРОТИВОТУБЕРКУЛЁЗНУЮ ВАКЦИНАЦИЮ ВАКЦИНОЙ БЦЖ И БЦЖ-М

Introduction. The effectiveness of TB vaccination is low in more than half of children with tuberculosis, which is confirmed by the small size of the post-vaccination scar or its absence. Having a residual virulence, the BCG strain can cause the development of post-vaccination complications. Objective – to conduct a comparative analysis of the frequency and structure of complications of TB vaccination with BCG and BCG-M in children. Material and methods. The analysis of the frequency and structure of complications was carried out in 284 children in BCG vaccination, in 273 children in BCG-M vaccine. Results. The use of BCG-M vaccine reduced the frequency and proportion of complications, and improved the structure of post-vaccination complications. The development of complications is associated with altered immunological reactivity of the child, which is manifested by a decrease in the activation potential of T-lymphocytes and functional insufficiency of humoral immune cells. Conclusions. During the period of TB vaccination, a thorough clinical and laboratory analysis of children with perinatal pathology is necessary to exclude immune insufficiency and reduce the risk of complications.

A pilot study of minimal invasion combined PDL/Nd:YAG laser in treating facial epidermoid cyst.

To compare the efficacy and complication of minimal invasion and combined pulsed dye laser/Nd:YAG laser and traditional surgical excision in the treatment of facial epidermoid cyst. A total of 100 patients with facial epidermoid cyst aged from 16 to 65years and cyst diameter ranged from 0.3 to 3.0cm were treated and followed up. Patients were divided into the minimal invasion and combined pulsed dye laser/Nd:YAG laser treatment group and traditional surgical excision group. All patients were followed up for 12months including scar size, recurrence rate, incidence of complications, and patient global satisfaction. The mean operative time in the minimal invasion and combined pulsed dye laser/Nd:YAG laser treatment was 15.23±7.02minutes, which is significantly shorter than that of surgical excision (27.26±10.12minutes, P<.05). After 12months, the average scar size in minimal invasion and combined pulsed dye laser/Nd:YAG laser group was 0.54±0.35cm, while that of traditional surgical excision group was 1.77±0.81cm (P<.05). No statistical difference was found between two groups in the wounds split, hematoma, early and late recurrence rates (P>.05), while the patients' global satisfaction in the pulsed dye laser/Nd:YAG laser group is much higher than that of the traditional surgical excision group. The treatment of minimal invasion and combined pulsed dye laser/Nd:YAG laser is effective and safe for medium-size facial epidermoid cysts. For facial epidermoid cyst ranging for 0.3cm to 3.0cm, considering the cosmetic factors, minimal invasion and combined pulsed dye laser/Nd:YAG laser should be particularly recommended.

Catheter ablation of ventricular tachycardia in ischemic cardiomyopathy: Impact of concomitant amiodarone therapy on short- and long-term clinical outcomes

Substrate catheter ablation of scar-related ventricular tachycardia (VT) is a widely accepted therapeutic option for patients with ischemic cardiomyopathy (ICM). The purpose of this study was to investigate whether concomitant amiodarone therapy affects procedural outcomes. A total of 134 consecutive patients (89% male; age 66± 10 years) with ICM undergoing catheter ablation of VT were included in the study. Patients were sorted by amiodarone therapy before ablation. In all patients, a substrate-based catheter ablation (endocardial ± epicardial) in sinus rhythm abolishing all "abnormal" electrograms within the scar was performed. The endpoint of the procedure was VT noninducibility. After the ablation procedure, all antiarrhythmic medications were discontinued. All patients had an implantable cardioverter-defibrillator, and recurrences were analyzed through the device. In 84 patients (63%), the ablation was performed on amiodarone; the remaining 50 patients (37%) were off amiodarone. Patients had comparable baseline characteristics. Mean scar size area was 143.6 ± 44.9 cm2 on amiodarone vs 139.2 ± 36.8 cm2 off amiodarone (P = .56). More radiofrequency time was necessary to achieve noninducibility in the off-amiodarone group compared to the on-amiodarone group (68.1 ± 20.1 minutes vs 51.5 ± 19.7 minutes; P <.001). In addition, due to persistent VT inducibility, more patients in the off-amiodarone group required epicardial ablation than in the on-amiodarone group (13/50 [26%] vs 5/84 [6%], respectively; P <.001). During mean follow-up of 23.9 ± 11.6 months, recurrence of any ventricular arrhythmias off antiarrhythmic drugs was 44% (37/84) in the on-amiodarone group vs 22% (11/50) in the off-amiodarone group (P = .013). Albeit, VT noninducibility after substrate catheter ablation for scar related VT was achieved faster, with less radiofrequency time and less need for epicardial ablation in patients taking amiodarone, these patients had significantly higher VT recurrence at long-term follow-up when this medication was discontinued.

Mesenchymal Stem Cells Pretreatment With Stromal-Derived Factor-1 Alpha Augments Cardiac Function and Angiogenesis in Infarcted Myocardium

BackgroundStem cell therapy is among the novel approaches for the treatment of post-myocardial infarction cardiomyopathy. This study aims to compare the effect of stromal-derived factor 1 α (SDF1α), mesenchymal stem cells (MSCs) in combination with the lentiviral production of vascular endothelial growth factor (VEGF) on infarct area, vascularization and eventually cardiac function in a rat model of myocardial infarction (MI). MethodsThe influence of SDf1α on MSCs survival was investigated. MSCs were transduced via a lentiviral vector containing VEGF. After that, the effect of mesenchymal stem cell transfection of VEGF-A165 and SDf1α preconditioning on cardiac function and scar size was investigated in five groups of MI rat models. The MSC survival, cardiac function, scar size, angiogenesis, and lymphocyte count were assessed 72 hours and 6 weeks after cell transplantation. ResultsSDF1α decreased the lactate dehydrogenase release in MSCs significantly. Also, the number of viable cells in the SDF1α-pretreated group was meaningfully more than the control. The left ventricular systolic function significantly enhanced in groups with p240MSC, SDF1αMSC, and VEGF-A165MSC in comparison to the control group. ConclusionsThese findings suggest that SDF1α pretreatment and overexpressing VEGF in MSCs could augment the MSCs' survival in the infarcted myocardium, reduce the scar size, and improve the cardiac systolic function.

Outcome of the acellular dermal matrix and split thickness skin graft in release of post burn contractures in hand.

Objective: To determine the frequency of success of acellular dermal matrix and split thickness skin graft in release of post burn contractures in hand using Vancouver scar scale. Study Design: Descriptive Case Series. Setting: Department of Plastic Surgery, Jinnah Burn and Reconstructive Surgery Center, Lahore. Period: 1st March, 2019 to 30th October, 2019. Material &amp; Method: A descriptive case series conducted at Plastic Surgery Department, Jinnah Burn and Reconstructive Surgery Center, Lahore. A sample size of 75 patients, who full filled the inclusion criteria, was selected through non probability consecutive sampling Informed consent was obtained from all the patients. Pre-operative photography was done to compare the post-operative results. After the release of contractures, coverage with acellular dermis and split thickness skin graft was performed. All the patients were followed up to 2 months and the outcome was assessed by Vancouver Scar Scale. The collected data was entered and analyzed by using SPSS version 20. Descriptive statistics were calculated. Quantitative variables like age, size of scar were presented as mean, ± standard deviation. Qualitative variables were presented as frequencies and percentages. Results: Mean age of patient was 30 ± 9 years. Among them 40 were males and 35 females. Vancouver scale showed successful outcome (score ≤4) in 70.66 % of the patients. Partial release of contracture was the major complication seen in 5.33% of cases. Conclusion: Acelluar dermal matrix followed by split thickness skin graft is a very reliable option for coverage after release of post-burn contractures in hand as it provides very pliable, thin and lax skin with good color match and better contour to surrounding tissue.

Comparison between the portable pressure measuring device and PicoPress® for garment pressure measurement on hypertrophic burn scar during compression therapy

PurposeThe current standard treatment for hypertrophic scars following burn injury is pressure garment therapy. The experimenters developed the novel portable pressure measuring device using silicon piezoresistive sensors. As PicoPress® is the most accurate (i.e., lowest variation and error) manometric sensor for pressure measurement, we sought to compare and examine the accuracy of the novel device regarding in vitro pressure measurements at the hypertrophic scar–pressure garment interface. MethodsThe novel device was designed to operate in non-corrosive media, such as air. The device can use up to six pressure sensing points and was developed to adjust the number of pressure sensors according to the size of the scar. Pressure measurements were acquired through a readout circuit consisting of an analog-to-digital converter, a microprocessor, and a Bluetooth transmission module for wireless data transmission to an external device. All signals were converted into mean pressure expressed in millimeters of mercury (mmHg). The mean pressure values measured by the sensors were compared to those obtained from PicoPress®. 55 garment pressures recordings were obtained from the sensors over this study conducted in 2018–February 2020. We then analyzed the test–retest reliability using the intraclass correlation coefficients (ICC). PicoPress® was also employed in the same pressure garments for obtaining similar measurements. A two way random effects model ICC with 95% confidence intervals was used to compare the mean pressure values obtained from the silicon piezoresistive sensors to the PicoPress® measurements. ResultsThe test–retest reliability of the pressure sensors was close to the acceptable level for clinical use regarding stationary interface pressure measurement (ICC = 0.99, 95% CI 0.990−0.997). The mean pressure obtained from the silicon piezoresistive pressure sensors showed an accordance with the measurements from PicoPress® (ICC = 0.97, 95% CI 0.947−0.985). ConclusionThe novel device may present a viable alternative to PicoPress® for garment pressure measurements. In addition, the novel device improves adaptability to the hypertrophic scar shape and size. Complementary characteristics such as wireless transmission to an external device may allow burn patients to continuously wear the device for real-time measurements during pressure garment therapy, thus improving existing devices including PicoPress®.

CMR feature tracking remote myocardial strain analyses for optimized risk prediction following acute myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance myocardial feature tracking (CMR-FT) derived global strain assessments provide incremental prognostic information in patients following acute myocardial infarction (AMI). Functional analyses of the remote myocardium (RM) are scarce and whether they provide an additional prognostic value in these patients is unknown. Methods 1052 patients following acute myocardial infarction were included. CMR imaging and strain analyses as well as scar size quantification were performed after reperfusion by primary percutaneous coronary intervention. The occurrence of major adverse cardiac events (MACE) within 12 months after the index event was defined as primary clinical endpoint. Results Patients with MACE had significantly lower RM circumferential strain (CS) compared to those without MACE. A cut-off value for RM CS of -25.8% best identified high-risk patients (p &amp;lt; 0.001 on log-rank testing) and impaired RM CS was a strong predictor of MACE (HR 1.05, 95% CI 1.07-1.14, p = 0.003). RM CS provided further risk stratification amongst patients considered at risk according to established CMR parameters for 1.) patients with reduced left ventricular ejection fraction (LVEF) ≤ 35 % (p = 0.002 on log-rank testing), 2.) patients with reduced global circumferential strain (GCS) &amp;gt; -18,3 % (p = 0.015 on log-rank testing), and 3.) patients with large microvascular obstruction ≥ 1.46 % (p = 0.038 on log-rank testing). Conclusion CMR-FT derived RM CS is a useful parameter to characterize the response of RM and allows improved stratification following AMI beyond commonly used parameters, especially of high-risk patients.

Polymer Cell Surface Coating Enhances Mesenchymal Stem Cell Retention and Cardiac Protection.

Mesenchymal stem cell (MSC) therapy has been widely tested in clinical trials to promote healing post-myocardial infarction. However, low cell retention and the need for a large donor cell number in human studies remain a key challenge for clinical translation. Natural biomaterials such as gelatin are ideally suited as scaffolds to deliver and enhance cell engraftment after transplantation. A potential drawback of MSC encapsulation in the hydrogel is that the bulky matrix may limit their biological function and interaction with the surrounding tissue microenvironment that conveys important injury signals. To overcome this limitation, we adopted a gelatin methacrylate (gelMA) cell-coating technique that photocross-links gelatin on the individual cell surface at the nanoscale. The present study investigated the cardiac protection of gelMA coated, hypoxia preconditioned MSCs (gelMA-MSCs) in a murine myocardial infarction (MI) model. We demonstrate that the direct injection of gelMA-MSC results in significantly higher myocardial engraftment 7 days after MI compared to uncoated MSCs. GelMA-MSC further amplified MSC benefits resulting in enhanced cardioprotection as measured by cardiac function, scar size, and angiogenesis. Improved MSC cardiac retention also led to a greater cardiac immunomodulatory function after injury. Taken together, this study demonstrated the efficacy of gelMA-MSCs in treating cardiac injury with a promising potential to reduce the need for donor MSCs through enhanced myocardial engraftment.

Texture-based probability mapping for automatic scar assessment in late gadolinium-enhanced cardiovascular magnetic resonance images

PurposeTo evaluate a novel texture-based probability mapping (TPM) method for scar size estimation in LGE-CMRI. MethodsThis retrospective proof-of-concept study included chronic myocardial scars from 52 patients. The TPM was compared with three signal intensity-based methods: manual segmentation, full-width-half-maximum (FWHM), and 5-standard deviation (5-SD). TPM is generated using machine learning techniques, expressing the probability of scarring in pixels. The probability is derived by comparing the texture of the 3 × 3 pixel matrix surrounding each pixel with reference dictionaries from patients with established myocardial scars. The Sørensen-Dice coefficient was used to find the optimal TPM range. A non-parametric test was used to test the correlation between infarct size and remodeling parameters. Bland-Altman plots were performed to assess agreement among the methods. ResultsThe study included 52 patients (76.9% male; median age 64.5 years (54, 72.5)). A TPM range of 0.328–1.0 was found to be the optimal probability interval to predict scar size compared to manual segmentation, median dice (25th and 75th percentiles)): 0.69(0.42–0.81). There was no significant difference in the scar size between TPM and 5-SD. However, both 5-SD and TPM yielded larger scar sizes compared with FWHM (p < 0.001 and p = 0.002). There were strong correlations between scar size measured by TPM, and left ventricular ejection fraction (LVEF, r = −0.76, p < 0.001), left ventricular end-diastolic volume index (r = 0.73, p < 0.001), and left ventricular end-systolic volume index (r = 0.75, p < 0.001). ConclusionThe TPM method is comparable with current SI-based methods, both for the scar size assessment and the relationship with left ventricular remodeling when applied on LGE-CMRI.

Determinants of Bacille Calmette-Guérin scarification in Danish children

BackgroundStudies in low-income countries have shown that among Bacille Calmette-Guérin (BCG) vaccinated children, those who develop a BCG-scar have significantly better survival than those who do not develop a scar. In a Danish multicenter randomized clinical trial we assessed determinants for developing a BCG-scar and for BCG scar size following neonatal BCG vaccination. MethodsAt three Danish hospitals, newborns were randomized 1:1 to BCG vaccination or no BCG vaccination. The infants were invited for a clinical examination at the ages of 3 and 13 months. At 13 months, the scar site was inspected and scar size measured. We investigated three groups of determinants; external, parental, and individual-level determinants on relative scar prevalence and differences in median scar sizes. ResultsAmong 2118 BCG vaccinated infants, 2039 (96 %) were examined at 13 months; 1857 of these (91 %) had developed a BCG-scar. Compared with Copenhagen University Hospital, Hvidovre (85 %), Copenhagen University Hospital, Rigshospitalet had a scar prevalence of 95 % (adjusted Prevalence ratio (aPR) = 1.24 [CI 95 %: 1.18 to 1.30]); it was 93 % at Kolding Hospital (aPR 1.27 [CI 95 %: 1.19 to 1.35]). Increasing vaccine experience was positively associated with developing a scar and with scar size. ConclusionAcross multiple potential determinants of BCG scaring and size, logistical factors dominated. The results support that injection technique is an important determinant of developing a scar. Given the strong link between having a BCG scar and subsequent health, improved BCG vaccination technique could play a major role for child health.

A retrospective study to evaluate the efficacy and safety of staged purse-string sutures for the reconstruction of surgical defects on skin using computer image analysis program.

Background:Staged purse-string suturing has been recently introduced for the reconstruction of round or oval defects following tumor excision.Objective:The aim of this study was to evaluate the clinical advantage of staged purse-string suturing for the reconstruction of relatively large skin defects.Materials and Methods:Twenty-one patients who received staged purse-string sutures were included in the study. To evaluate the defects and scar sizes objectively, computer-based image analysis was used. A modified observer scar assessment scale (OSAS) was applied for evaluating the clinical efficacy.Results:The mean primary postsurgical defect size in the total 21 cases was 1446.2 ± 1187.2 mm2, and the mean final scar size was about 268.1 ± 252.3 mm2. The defect area decreased gradually as staged purse-string suturing was performed. The mean total modified OSAS was 7.96 ± 1.69.Conclusion:Staged purse-string sutures might be an alternative reconstructive method for relatively large round or oval skin defects.

Free-Breathing Motion-Corrected Single-Shot Phase-Sensitive Inversion Recovery Late-Gadolinium-Enhancement Imaging: A Prospective Study of Image Quality in Patients with Hypertrophic Cardiomyopathy.

ObjectiveMotion-corrected averaging with a single-shot technique was introduced for faster acquisition of late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging while free-breathing. We aimed to evaluate the image quality (IQ) of free-breathing motion-corrected single-shot LGE (moco-ss-LGE) in patients with hypertrophic cardiomyopathy (HCM).Materials and MethodsBetween April and December 2019, 30 patients (23 men; median age, 48.5; interquartile range [IQR], 36.5–61.3) with HCM were prospectively enrolled. Breath-held single-shot LGE (bh-ss-LGE) and free-breathing moco-ss-LGE images were acquired in random order on a 3T MR system. Semi-quantitative IQ scores, contrast-to-noise ratios (CNRs), and quantitative size of myocardial scar were assessed on pairs of bh-ss-LGE and moco-ss-LGE. The mean ± standard deviation of the parameters was obtained. The results were compared using the Wilcoxon signed-rank test.ResultsThe moco-ss-LGE images had better IQ scores than the bh-ss-LGE images (4.55 ± 0.55 vs. 3.68 ± 0.45, p < 0.001). The CNR of the scar to the remote myocardium (34.46 ± 11.85 vs. 26.13 ± 10.04, p < 0.001), scar to left ventricle (LV) cavity (13.09 ± 7.95 vs. 9.84 ± 6.65, p = 0.030), and LV cavity to remote myocardium (33.12 ± 15.53 vs. 22.69 ± 11.27, p < 0.001) were consistently greater for moco-ss-LGE images than for bh-ss-LGE images. Measurements of scar size did not differ significantly between LGE pairs using the following three different quantification methods: 1) full width at half-maximum method; 23.84 ± 12.88% vs. 24.05 ± 12.81% (p = 0.820), 2) 6-standard deviation method, 15.14 ± 10.78% vs. 15.99 ± 10.99% (p = 0.186), and 3) 3-standard deviation method; 36.51 ± 17.60% vs. 37.50 ± 17.90% (p = 0.785).ConclusionMotion-corrected averaging may allow for superior IQ and CNRs with free-breathing in single-shot LGE imaging, with a herald of free-breathing moco-ss-LGE as the scar imaging technique of choice for clinical practice.

Postsurgery echocardiography can predict the amount of ischemia-reperfusion injury and the resultant scar size.

Despite advances in the diagnosis and treatment of ischemic heart disease (IHD), it remains the leading cause of death globally. Thus, there is a need to investigate the underlying pathophysiology and develop new therapies for the prevention and treatment of IHD. Murine models are widely used in IHD research because they are readily available, relatively inexpensive, and can be genetically modified to explore mechanistic questions. Ischemia-reperfusion (I/R)-induced myocardial infarction in mice is produced by the blockage followed by reperfusion of the left anterior descending branch (LAD) to imitate human IHD disease and its treatment. This I/R model can be widely used to investigate the potential reparative effect of putative treatments in the setting of reperfusion. However, the surgical technique is demanding and can produce an inconsistent amount of damage, which can make identification of treatment effects challenging. Therefore, determining which hearts have been significantly damaged by I/R is an important consideration in studies designed to either explore the mechanisms of disrupted function or test possible therapies. Noninvasive echocardiography (ECHO) is often used to determine structural and functional changes in the mouse heart following injury. In the present study, we determined that ECHO performed 3 days post I/R surgery could predict the permanent injury produced by the ischemic insult.NEW & NOTEWORTHY We believe our work is noteworthy due to its creation of standards for early evaluation of the level of myocardial injury in mouse models of ischemia-reperfusion. This improvement to study design could reduce the sample sizes used in evaluating therapeutics and lead to increased confidence in conclusions drawn regarding the therapeutic efficacy of treatments tested in these translational mouse models.

Multiple Intravenous Injections of Valproic Acid-Induced Mesenchymal Stem Cell from Human-Induced Pluripotent Stem Cells Improved Cardiac Function in an Acute Myocardial Infarction Rat Model.

Mounting evidence indicates that the mesenchymal stem cell (MSC) injection is safe and efficacious for treating cardiomyopathy; however, there is limited information relating to multiple intravenous injections of human-induced pluripotent stem cell-derived mesenchymal stem cell (hiPSC-MSC) and long-term evaluation of the cardiac function. In the current study, MSC-like cells were derived from human-induced pluripotent stem cells through valproic acid (VPA) induction and continuous cell passages. The derived spindle-like cells expressed MSC-related markers, secreted angiogenic and immune-regulatory factors, and could be induced to experience chondrogenic and adipogenic differentiation. During the induction process, expression of epithelial-to-mesenchymal transition- (EMT-) related gene N-cadherin and vimentin was upregulated to a very high level, and the expression of pluripotency-related genes Sox2 and Oct4 was downregulated or remained unchanged, indicating that VPA initiated EMT by upregulating the expression of EMT promoting genes and downregulating that of pluripotency-related genes. Two and four intravenous hiPSC-MSC injections (106 cells/per injections) were provided, respectively, to model rats one week after acute myocardial infarction (AMI). Cardiac function parameters were dynamically monitored during a 12-week period. Two and four cell injections significantly the improved left ventricular ejection fraction and left ventricular fractional shortening; four-injection markedly stimulated angiogenesis reduced the scar size and cell apoptosis number in the scar area in comparison with that of the untreated control model rats. Although the difference was insignificant, the hiPSC-MSC administration delayed the increase of left ventricular end-diastolic dimension to different extents compared with that of the PBS-injection control. No perceptible immune reaction symptom or hiPSC-MSC-induced tumour formation was found over 12 weeks. Compared with the PBS-injection control, four injections produced better outcome than two injections; as a result, at least four rounds of MSC injections were suggested for AMI treatment.

From the Literature

From the Literature

Olduvai's oldest Oldowan

Previously, Olduvai Bed I excavations revealed Oldowan assemblages <1.85 Ma, mainly in the eastern gorge. New western gorge excavations locate a much older ∼2.0 Ma assemblage between the Coarse Feldspar Crystal Tuff (∼2.015 Ma) and Tuff IA (∼1.98 Ma) of Lower Bed I, predating the oldest eastern gorge DK assemblage below Tuff IB by ∼150 kyr. We characterize this newly discovered fossil and artifact assemblage, adding information on landscape and hominin resource use during the ∼2.3–2.0 Ma period, scarce in Oldowan sites. Assemblage lithics and bones, lithofacies boundaries, and phytolith samples were surveyed and mapped. Sedimentological facies analysis, tephrostratigraphic and sequence stratigraphic principles were applied to reconstruct paleoenvironments and sedimentary processes of sandy claystone (lake), sandstone (fluvial), and sandy diamictite (debris flow) as principal lithofacies. Artifacts, sized, weighed, categorized, were examined for petrography, retouch, and flake scar size. Taxonomic classifications and taphonomic descriptions of faunal remains were made, and phytoliths were categorized based on reference collections. Lithics are dominantly quartzite, mainly debitage and less frequently simple cores, retouched pieces, and percussors. Well-rounded spheroids and retouched flakes are rare. Identifiable taxa, Ceratotherium cf. simum (white rhinoceros) and Equus cf. oldowayensis (extinct zebra), accord with nearby open savanna grasslands, inferred from C3 grass, mixed and/or alternating with C4 grass-dominated phytolith assemblages. Palms, sedges, and dicots were also identified from phytoliths. Diatoms and sponge spicules imply nearby freshwater. The assemblage accumulated at the toe of a Ngorongoro Volcano-sourced fan-delta apron of stacked debris flows, fluvials, and tuffs, preserving fossil tree stumps and wooded grassland phytoliths farther upfan. It formed after the climax of Ngorongoro volcanic activity during a Paleolake Olduvai lowstand and was then buried and preserved by lacustrine clays, marking the first of two lake transgressions, signifying wetter climates. Orbital precessional lake cycles were superposed upon multimillennial (∼4.9 kyr) lake fluctuations.

The impact of incisional negative pressure wound therapy on the wound healing process after midline sternotomy.

Previous studies have reported that the use of incisional negative pressure wound therapy (INPWT) might reduce the incidence of wound infections, although its mechanism remains unknown. We designed a prospective study to explore the effects of INPWT on different stages of the wound healing process. After meeting the inclusion criteria, 108 patients were enrolled. Based on exclusion criteria four patients were excluded and 104 patients were randomised into two groups. INPWT was applied after primary closure of the midline sternotomy in the study group (n = 52), while conventional wound dressing was applied in the control group (n = 52). We documented the incidence of deep sternal wound infections and analysed the pre‐ and postoperative inflammatory biomarkers and scar size in both groups. No wound infections were observed in the study group compared with six cases (11.1%) in the control group, (P = .026). No significant differences were observed in the inflammatory biomarkers between the groups. Scar size was significantly smaller in the study group. We concluded that INPWT has less effect on the inflammatory phase and appears to have more effect on the proliferation phase through pronounced scar formation.

Improvement of late gadolinium enhancement image quality using a deep learning\u2013based reconstruction algorithm and its influence on myocardial scar quantification

ObjectivesThe aim of this study was to assess the effect of a deep learning (DL)–based reconstruction algorithm on late gadolinium enhancement (LGE) image quality and to evaluate its influence on scar quantification.MethodsSixty patients (46 ± 17 years, 50% male) with suspected or known cardiomyopathy underwent CMR. Short-axis LGE images were reconstructed using the conventional reconstruction and a DL network (DLRecon) with tunable noise reduction (NR) levels from 0 to 100%. Image quality of standard LGE images and DLRecon images with 75% NR was scored using a 5-point scale (poor to excellent). In 30 patients with LGE, scar size was quantified using thresholding techniques with different standard deviations (SD) above remote myocardium, and using full width at half maximum (FWHM) technique in images with varying NR levels.ResultsDLRecon images were of higher quality than standard LGE images (subjective quality score 3.3 ± 0.5 vs. 3.6 ± 0.7, p < 0.001). Scar size increased with increasing NR levels using the SD methods. With 100% NR level, scar size increased 36%, 87%, and 138% using 2SD, 4SD, and 6SD quantification method, respectively, compared to standard LGE images (all p values < 0.001). However, with the FWHM method, no differences in scar size were found (p = 0.06).ConclusionsLGE image quality improved significantly using a DL-based reconstruction algorithm. However, this algorithm has an important impact on scar quantification depending on which quantification technique is used. The FWHM method is preferred because of its independency of NR. Clinicians should be aware of this impact on scar quantification, as DL-based reconstruction algorithms are being used.Key Points• The image quality based on (subjective) visual assessment and image sharpness of late gadolinium enhancement images improved significantly using a deep learning–based reconstruction algorithm that aims to reconstruct high signal-to-noise images using a denoising technique.• Special care should be taken when scar size is quantified using thresholding techniques with different standard deviations above remote myocardium because of the large impact of these advanced image enhancement algorithms.• The full width at half maximum method is recommended to quantify scar size when deep learning algorithms based on noise reduction are used, as this method is the least sensitive to the level of noise and showed the best agreement with visual late gadolinium enhancement assessment.

Abstract 14391: Transient Cell Cycle Induction in Cardiomyocytes is a Promising Approach to Treat Ischemia Induced Heart Failure

Rationale: The regenerative capacity of the heart to repair itself after myocardial infarction (MI)is limited. Our previous study showed that ectopic introduction of Cdk1/CyclinB1 andCdk4/CyclinD1 complexes (4F) promotes cardiomyocyte proliferation in vitro and in vivo andimproves cardiac function after MI. However, its clinical application is limited due to the concernsfor tumorigenic potential in other organs. Objectives: To first, identify on a single cell transcriptomic basis the necessary reprogrammingsteps that cardiomyocytes need to undertake to progress through the proliferation processfollowing 4F overexpression, and then, to determine the pre-clinical efficacy of transient andcardiomyocyte specific expression of 4F in improving cardiac function after MI in small and largeanimals. Methods and Results: Temporal bulk and single cell RNAseq of mature hiPS-CMs treated with4F or LacZ control for 24, 48, or 72 h revealed full cell cycle reprogramming in 15% of thecardiomyocyte population which was associated with sarcomere disassembly and metabolicreprogramming. Transient overexpression of 4F specifically in cardiomyocytes was achievedusing non-integrating lentivirus (NIL) driven by TNNT2 (TNNT2-4F-NIL). One week after inductionof ischemia-reperfusion injury in rats or pigs, TNNT2-4F-NIL or control virus was injectedintramyocardially. Compared with controls, rats or pigs treated with TNNT2-4F-NIL showed a 20-30% significant improvement in ejection fraction and scar size four weeks after treatment, asassessed by echocardiography and histological analysis. Quantification of cardiomyocyteproliferation in pigs using a novel cytokinesis reporter showed that ~10% of the cardiomyocyteswithin the injection site were labelled as daughter cells following injection with TNNT2-4F-NILcompared with ~0.5% background labelling in control groups. Conclusions: We provide the first understanding of the process of forced cardiomyocyteproliferation and advanced the clinical applicability of this approach through minimization ofoncogenic potential of the cell cycle factors using a novel transient and cardiomyocyte-specificviral construct.