Comparison of Laser Doppler Imaging (LDI) and clinical assessment in differentiating between superficial and deep partial thickness burn wounds

Erastin promotes random-pattern skin flaps survival by inducing mTORC1-TFEB mediated autophagy

Random-pattern skin flaps are important method for skin reconstruction after defect; however, the distal end of flaps is not easily viable due to inadequate nutrient supply. Erastin is a well-established ferroptosis inducer, but our study found that low-dose of erastin (2 μM) may reduce nutrient deficiency induced cell death in human umbilical vein endothelial cells (HUVECs). RNA-seq analysis suggested that its role was related to autophagy regulation. Follow-up studies have shown that the use of autophagy inhibitors or the knockdown of TFEB in HUVECs can both reduce the anti-apoptotic effect of erastin in HUVECs. Mechanism study demonstrated that erastin can suppress mTORC1 and promote TFEB activity in HUVECs, suggesting that the effect of erastin on the survival of HUVECs under nutrient deprivation conditions is regulated by mTORC1/TFEB. Subsequently, we evaluated the effect of erastin on the survival of random-pattern skin flaps in mice in vivo. On the postoperative day 7, we observed a significant increase in flap survival area, blood perfusion, and microvascular density after erastin treatment; also, erastin treatment showed enhanced autophagy within the ischemic region. In summary, our study demonstrates that low-dose of erastin may suppress cell death in endothelial cells under nutrient deficiency condition, and its effects may relate to the mTORC1-TFEB medicated autophagy regulation, erastin treatment may be a potential therapy for random-pattern skin flaps.

Multispectral Imaging-Based System for Detecting Tissue Oxygen Saturation With Wound Segmentation for Monitoring Wound Healing

OBJECTIVE

Blood circulation is an important indicator of wound healing. In this study, a tissue oxygen saturation detecting (TOSD) system that is based on multispectral imaging (MSI) is proposed to quantify the degree of tissue oxygen saturation (StO2) in cutaneous tissues.

METHODS

A wound segmentation algorithm is used to segment automatically wound and skin areas, eliminating the need for manual labeling and applying adaptive tissue optics. Animal experiments were conducted on six mice in which they were observed seven times, once every two days. The TOSD system illuminated cutaneous tissues with two wavelengths of light - red ([Formula: see text] nm) and near-infrared ([Formula: see text] nm), and StO2 levels were calculated using images that were captured using a monochrome camera. The wound segmentation algorithm using ResNet34-based U-Net was integrated with computer vision techniques to improve its performance.

RESULTS

Animal experiments revealed that the wound segmentation algorithm achieved a Dice score of 93.49%. The StO2 levels that were determined using the TOSD system varied significantly among the phases of wound healing. Changes in StO2 levels were detected before laser speckle contrast imaging (LSCI) detected changes in blood flux. Moreover, statistical features that were extracted from the TOSD system and LSCI were utilized in principal component analysis (PCA) to visualize different wound healing phases. The average silhouette coefficients of the TOSD system with segmentation (ResNet34-based U-Net) and LSCI were 0.2890 and 0.0194, respectively.

CONCLUSION

By detecting the StO2 levels of cutaneous tissues using the TOSD system with segmentation, the phases of wound healing were accurately distinguished. This method can support medical personnel in conducting precise wound assessments. Clinical and Translational Impact Statement-This study supports efforts in monitoring StO2 levels, wound segmentation, and wound healing phase classification to improve the efficiency and accuracy of preclinical research in the field.

Non-invasive medical imaging technology for the diagnosis of burn depth

Currently, the clinical diagnosis of burn depth primarily relies on physicians' judgements based on patients' symptoms and physical signs, particularly the morphological characteristics of the wound. This method highly depends on individual doctors' clinical experience, proving challenging for less experienced or primary care physicians, with results often varying from one practitioner to another. Therefore, scholars have been exploring an objective and quantitative auxiliary examination technique to enhance the accuracy and consistency of burn depth diagnosis. Non-invasive medical imaging technology, with its significant advantages in examining tissue surface morphology, blood flow in deep and changes in structure and composition, has become a hot topic in burn diagnostic technology research in recent years. This paper reviews various non-invasive medical imaging technologies that have shown potential in burn depth diagnosis. These technologies are summarized and synthesized in terms of imaging principles, current research status, advantages and limitations, aiming to provide a reference for clinical application or research for burn specialists.

Outpatient and Minor Burn Treatment

Burn injuries are common; most burn injuries may be considered minor and are suitable for outpatient management. Steps should be taken to ensure that patients managed in this way still retain access to the full burns multidisciplinary team, and that admission remains an option if complications develop or according to patient preference. Modern antimicrobial dressings, outreach nursing teams, and the use of telemedicine means that the number of patients that can be safely managed without hospital admission is likely to increase further.

Laser doppler imaging - the role of poor burn perfusion in predicting healing time and guiding operative management

AIM

To identify if the proportion of poor blood flow (blue) within an LDI (Laser doppler Imaging) image of a burn independently correlates with healing time.

METHODS

Patient age, gender, burn type, and burn surface area were collected from the IBID (International Burn Injury Database). All LDI images were copied from the MoorLDI2-BI- Laser Doppler (MLDI) Scanner, onto Adobe Photoshop® version 2020 for pixel counting analysis and calculation of % TBSA (Total Body Surface Area) blue. Multiple linear regression analysis determined whether a proportional relationship was present for each parameter (age, gender, % TBSA Blue and comorbidities) with healing time.

RESULTS

110 patients with 197 burns were scanned with MLDI. Median age was 5 years (IQR 1-6). Median burn surface area was 1.5% (IQR 1-2.4). 56.4% of patients were male and patients were scanned an average of 2.68 days (SD±1.37) following burn injury. Number of physical comorbidities and age were found to have a statistically significant relationship with healing time (p = 0.03, p = 0.002). Gender and %TBSA blue did not have a statistically significant relationship with healing time (p = 0.07 and p = 0.058 respectively). We found a statistically significant difference in the mean healing time between burns with and without blue (3.43 weeks vs. 2.80 weeks, p = 0.0001). % TBSA Blue was more than four times higher in the operated group (0.48% vs. 0.11%) and was shown to have a statistically significant relationship with decision to operate (p = 0.027). Positive predictive value for the presence of blue on operative rate was 71.6%. Age, gender and number of comorbidities did not have a statistically significant influence on operative rate (p = 0.07, p = 0.50 and p = 0.49).

CONCLUSION

% TBSA blue was not found to be a reliable independent indicator of burn healing time, but the presence of blue within an LDI image, advanced patient age and increased number of comorbidities did have a statistically significant relationship with healing time. This suggests their standardised inclusion into management decisions regarding intermediate depth burns is warranted.

Evaluation of Bromelain-Based Enzymatic Debridement Combined with Laser Doppler Imaging and Healing of Burn Wounds

Background

Accurate estimation of burn depth is crucial for correct treatment decision making. Bromelain-based enzymatic debridement (ED) may improve clinical assessment of burn depth. Laser Doppler imaging (LDI) provides a valuable indicator of burn depth by analyzing microcirculation within tissue beds. This study aimed to evaluate bromelain-based enzymatic debridement combined with laser Doppler imaging and healing of 42 wounds in 19 patients with mixed second- and third-degree thermal burns.

Material/Methods

We included 42 wounds in 19 patients with mixed deep dermal and full-thickness thermal burns. All patients were treated with eschar-specific removal agent for ED. The perfusion of each wound after ED was assessed using LDI. Healing time was estimated by 2 experienced burn surgeons and marked by the observation of epithelization. The usefulness of the LDI performed after ED in predicting healing time was estimated. The findings were analyzed to determine a cut-off value for LDI that indicates if a burn will heal spontaneously.

Results

We observed that burn wounds with higher mean perfusion healed faster. The analysis showed a strong relationship between perfusion after ED and healing time (Spearman rank correlation coefficient=−0.803). A mean perfusion greater than 296.89 indicated that the wound could heal spontaneously and does not require skin grafting.

Conclusions

LDI examination of an already debrided wound allows for a reliable assessment of perfusion at an early stage of treatment. The use of a safe and effective debridement method in conjunction with a non-invasive diagnostic tool could improve burn management.

Wireless microcurrent stimulation improves blood flow in burn wounds

RATIONALE

Skin breakdown, as in wounds, leads to an electric potential, defined as current of injury with the intent of wound closure. Burn wounds are defined by different zones of perfusion having a direct influence on further therapy (e.g. conservative management or skin grafting). We studied immediate, quantifiable effects of electric stimulation on skin perfusion in burn wounds.

METHOD

Wireless Microcurrent Stimulation (WMCS) was utilised as an adjunct therapeutic modality in 10 patients with partial thickness burn wounds. Microcirculation in the skin was quantified with a Laser Doppler (LDI) before and after WMCS treatment. We included a control group of 10 healthy individuals.

RESULTS

A single application of WMCS significantly increased mean flow, velocity and subsequently, haemoglobin and oxygen saturation in partial thickness burn wounds. In healthy skin these parameters increased, but were far less pronounced than in thermally injured skin.

CONCLUSION

This study revealed, for the first time that non-contact WMCS improves blood flow in critically perfused partial thickness burn wounds without disturbing the wound or systemically affecting the patient and may represent a promising adjunct tool in burn treatment, with the potential of faster healing by enhanced perfusion of burn wounds and reduction of the zone of stasis.

LEVEL OF EVIDENCE

III.

A novel method for objectively, rapidly and accurately evaluating burn depth via near infrared spectroscopy

The accurate and objective evaluation of burn depth is a significant challenge in burn wound care. Herein, we used near infrared spectroscopy (NIRS) technology to measure the different depth of thermal burns in ex vivo porcine models. Based on the intensity of the spectral signals and the diffuse reflection theory, we extracted the optical parameters involved in functional (total hemoglobin and water content) and structural (tissue scattered size and scattered particles) features that reflect the changes in burn depth. Next, we applied support vector regression to construct a model including the optical property parameters and the burn depth. Finally, we histologically verified the burn depth data collected via NIRS. The results showed that our inversion model could achieve an average relative error of about 7.63%, while the NIRS technology diagnostic accuracy was in the range of 50 μm. For the first time, this novel technique provides physicians with real-time burn depth information objectively and accurately.

The LDI Enigma Part II: Indeterminate depth burns, man or machine?

INTRODUCTION

Laser Doppler imaging is universally considered the most evidence-based method for objective burn depth assessment by accurately predicting burn wound healing potential. This study has analyzed how exactly laser Doppler imaging measurements can be useful in the early therapeutic decision making for patients with clinically indeterminate depth burns.

MATERIAL AND METHODS

An extensive survey, by questionnaire and in-depth interviews, was conducted among 51 burn centers worldwide to gain insight on the practical use of laser Doppler imaging.

RESULTS

Twenty-seven (53%) of the 51 burn centers contacted almost completely answered the 32 questions. Fifty-two percent of these centers (14/27) had at least 10 years of laser Doppler imaging experience. laser Doppler imaging was considered to be mainly or almost completely accurate by 89%. In case of discrepancy between clinical assessment and LDI, 41% relied more on clinical diagnosis, 25% delayed decision to operate, while 16% re-scanned the next day. The centers most experienced with laser Doppler imaging (13%) relied on it more. Final decisions for treatment were based on the combination of laser Doppler imaging and clinical assessment by 74%. Seventy percent of the centers almost never operated burns with laser Doppler imaging-red and would almost always operate burns with LDI-blue. Treatment decisions for intermediate laser Doppler imaging colors (pink, yellow and green) varied, with 76% basing decisions on other factors: % Total Body Surface Area (TBSA), general health, age, location of the burn, potential for colonization/infection, patient preference, compliance with aftercare, logistics, and socio-economic factors.

CONCLUSION

Laser Doppler imaging reduces the number of clinical indeterminate depth burns. For these intermediate depth burns on laser Doppler imaging, treatment decisions are based on a combination of interpretation ('man') and laser Doppler imaging measurements ('machine'). Thorough knowledge of confounding factors and validated laser Doppler imaging color code, consideration of surrounding laser Doppler imaging colors, the use of mean flux values, and not directly burn related factors are essential. Burn centers with most laser Doppler imaging experience considered laser Doppler imaging an indispensable diagnostic tool.

Is it better to reduce the intervals between pulsed dye laser treatments for port wine stains in children? Laser Doppler Imaging based study

BACKGROUND

Pulsed Dye Laser (PDL) is the treatment of choice of Port Wine Stains (PWS). Laser Doppler Imaging (LDI) has been used to evaluate the effectiveness of this treatment. In a previous study, we demonstrated that LDI allows an objective evaluation. The purpose of this study is to investigate if reducing the delay between two laser sessions could improve the clinical outcome.

METHOD

This prospective study was conducted from September 2015 to November 2017. Three Laser sessions were performed every month in twenty patients with PWS. The PWS response was assessed by LDI after each session and at the end of the third one. The present study was compared to the first one.

RESULTS

The LDI confirmed the efficacy of PDL treatment with an average blanching rate of 26.7 %. The response is statistically significant after each session. When we compare both studies, there is an average decrease in vascularization of 0.42 for the first study and 0.50 for the present one.

CONCLUSION

This study allows us to validate the use of LDI for the numerical evaluation of PDL effect on PWS in children. However, we cannot confirm that reducing the interval between laser sessions could improve therapeutic outcomes.

LEVELS OF EVIDENCE

Treatment Study Level II (Prospective Comparative Study).

Coming to Consensus: What Defines Deep Partial Thickness Burn Injuries in Porcine Models?

Deep partial thickness burns are clinically prevalent and difficult to diagnose. In order to develop methods to assess burn depth and therapies to treat deep partial thickness burns, reliable, accurate animal models are needed. The variety of animal models in the literature and the lack of precise details reported for the experimental procedures make comparison of research between investigators challenging and ultimately affect translation to patients. They sought to compare deep partial thickness porcine burn models from five well-established laboratories. In doing so, they uncovered a lack of consistency in approaches to the evaluation of burn injury depth that was present within and among various models. They then used an iterative process to develop a scoring rubric with an educational component to facilitate burn injury depth evaluation that improved reliability of the scoring. Using the developed rubric to re-score the five burn models, they found that all models created a deep partial thickness injury and that agreement about specific characteristics identified on histological staining was improved. Finally, they present consensus statements on the evaluation and interpretation of the microanatomy of deep partial thickness burns in pigs.

The Added Benefit of Combining Laser Doppler Imaging With Clinical Evaluation in Determining the Need for Excision of Indeterminate-Depth Burn Wounds

Background Managing indeterminate-depth burn wounds remains challenging. Laser Doppler Imaging (LDI) has been validated for burn wound depth and can influence the clinical assessment. Our study investigated the value of LDI as an adjunct in determining the need for excision. Methods Seventy American Burn Association (ABA)-verified burn centers were surveyed. A controlled pre-test assessment without LDI and post-test assessment with LDI of 100 indeterminate-depth burn wounds was conducted to evaluate the influence on the clinical judgment among different health professionals. Relative risk, analysis of variance (ANOVA), paired t-test, and intention-to-treat were used for analysis. A p-value [Formula: see text] 0.05 was considered significant.  Results Among 32 burn centers, three confirmed using LDI. Six thousand grader-image interactions were analyzed. There was a significant difference in the predictive accuracy for pre-LDI and post-LDI assessments when all graders were considered (51.9% ± 7.0 vs. 72.9% ± 7.9; p < 0.0001). Post-LDI assessment added 20.9% more accuracy than the pre-LDI assessment. The post-LDI assessment was 1.4 times more likely to correctly predict the need for excision and skin-grafting than the pre-LDI assessment. All groups had an improved performance post-LDI: Group 1 (physicians), 51.9 ± 7.5 versus 76.4±5; Group 2 (nurses), 52.1 ± 6.1 versus 72.7±7.7; and Group 3 (others), 51.7 ± 9.2 versus 68.6 ± 10.1. No statistical difference was observed between groups (p = 0.92).  Conclusion LDI makes the clinical examination of indeterminate-depth burn wounds more accurate. For every five LDI evaluations performed, one assessor changed their treatment plan as a result of this imaging technique. LDI is cost-effective and increases the accuracy of determining the severity of indeterminate-depth burn wounds.

Pediatric burn care: new techniques and outcomes

PURPOSE OF REVIEW

Thermal injury is a leading cause of morbidity and mortality in children. This review highlights the current management of thermal injury and its complications.

RECENT FINDINGS

Many recent advances in burn care have improved the outcomes of patients with thermal injury; however, variability does exist, and there are many opportunities for improvement. This review will highlight the complexity of issues encountered along the continuum of care for thermal injury patients. Accurate estimation of total burn surface area (TBSA) of a burn continues to be a challenge in pediatric patients. Variability continues to exist surrounding the management of burn resuscitation and complex wounds. Children with extensive burns have profound immune and metabolic changes that can lead to multiple complications, including infections, growth arrest, and loss of lean body mass. Standardization in measurements related to quality of life and psychological stress following pediatric thermal injury is much needed.

SUMMARY

The care of pediatric patients with thermal injury is complex and multifaceted. This review highlights the most recent advances in pediatric burn care.

Comparison of Deep Transfer Learning Techniques in Human Skin Burns Discrimination

While visual assessment is the standard technique for burn evaluation, computer-aided diagnosis is increasingly sought due to high number of incidences globally. Patients are increasingly facing challenges which are not limited to shortage of experienced clinicians, lack of accessibility to healthcare facilities and high diagnostic cost. Certain number of studies were proposed in discriminating burn and healthy skin using machine learning leaving a huge and important gap unaddressed; whether burns and related skin injuries can be effectively discriminated using machine learning techniques. Therefore, we specifically use transfer learning by leveraging pre-trained deep learning models due to deficient dataset in this paper, to discriminate two classes of skin injuries—burnt skin and injured skin. Experiments were extensively conducted using three state-of-the-art pre-trained deep learning models that includes ResNet50, ResNet101 and ResNet152 for image patterns extraction via two transfer learning strategies—fine-tuning approach where dense and classification layers were modified and trained with features extracted by base layers and in the second approach support vector machine (SVM) was used to replace top-layers of the pre-trained models, trained using off-the-shelf features from the base layers. Our proposed approach records near perfect classification accuracy in categorizing burnt skin ad injured skin of approximately 99.9%.

Eschar removal by bromelain based enzymatic debridement (Nexobrid®) in burns: European consensus guidelines update

INTRODUCTION

Bromelain-based Enzymatic Debridement has been introduced as an additional concept to the burn surgeon's armamentarium and is best indicated for mid-to deep dermal burns with mixed patterns. Increasing evidence has been published focusing on special regions and settings as well as on limitations of Enzymatic Debridement to improve patient care. To better guide Enzymatic Debridement in view of the increasing experience, there is a need to update the formerly published consensus guidelines with user-orientated recommendations, which were last produced in 2017.

METHODS

A multi-professional expert panel of plastic surgeons and burn care specialists from twelve European centers was convened, to assist in developing current recommendations for best practices with use of Enzymatic Debridement. Consensus statements were based on peer-reviewed publications and clinical relevance, and topics for re-evaluation and refinement were derived from the formerly published European guidelines. For consensus agreement, the methodology employed was an agreement algorithm based on a modification of the Willy and Stellar method. For this study on Enzymatic Debridement, consensus was considered when there was at least 80 % agreement to each statement.

RESULTS

The updated consensus guidelines from 2019 refer to the clinical experience and practice patterns of 1232 summarized patient cases treated by the panelists with ED in Europe (2017: 500 cases), reflecting the impact of the published recommendations. Forty-three statements were formulated, addressing the following topics: indications, pain management and anesthesia, large surface treatment, timing of application for various indications, preparation and application, post-interventional wound management, skin grafting, outcome, scar and revision management, cost-effectiveness, patient´s perspective, logistic aspects and training strategies. The degree of consensus was remarkably high, with consensus in 42 out of 43 statements (97.7%). A classification with regard to timing of application for Enzymatic Debridement was introduced, discriminating immediate/very early (≤12 h), early (12-72 h) or delayed (>72 h) treatment. All further recommendations are addressed in the publication.

CONCLUSIONS

The updated guidelines in this publication represent further refinement of the recommended indication, application and post-interventional management for the use of ED. The published statements contain detailed, user-orientated recommendations aiming to align current and future users and prevent pitfalls, e.g. for the successful implementation of ED in further countries like the USA. The significance of this work is reflected by the magnitude of patient experience behind it, larger than the total number of patients treated in all published ED clinical trials.

A Critical Update of the Assessment and Acute Management of Patients with Severe Burns

Significance: Burns are debilitating, life threatening, and difficult to assess and manage. Recent advances in assessment and management have occurred since a comprehensive review of the care of patients with severe burns was last published, which may influence research and clinical practice. Recent Advances: Recent advances have occurred in the understanding of burn pathophysiology, which has led to the identification of potential biomarkers of burn severity, such as protein C. There is new evidence about the potential superiority of natural colloids over crystalloids during fluid resuscitation, and new evidence about components of initial and perioperative management, including an improved understanding of pain following burns. Critical Issues: The limitations of the clinical examination highlight the need for imaging and biomarkers to assist in estimations of burn severity. Fluid resuscitation reduces mortality, although there is conjecture over the ideal method. The subsequent perioperative period is associated with significant morbidity and the evidence for preventing and treating pain, infection, and fluid overload while maximizing wound healing potential is described. Future Directions: Promising developments are ongoing in imaging technology, histopathology, biomarkers, and wound healing adjuncts such as hyperbaric oxygen therapy, topical negative pressure therapy, stem cell treatments, and skin substitutes. The greatest benefit from further research on management of patients with burns would most likely be derived from the elucidation of optimal fluid resuscitation protocols, pain management protocols, and surgical techniques from randomized controlled trials.

Comparative study of conventional and topical heparin treatment in second degree burn patients for burn analgesia and wound healing

OBJECTIVE

To compare clinical outcome of topical conventional with topical heparin treatment in 2nd degree or partial thickness (PTB) burn patients.

METHODS

Patients, between the ages of 14 and 60 years with 2nd degree burns involving <20%. Total body surface area (TBSA) on front of chest, abdomen and upper limbs excluding hands and lower limbs were enrolled from September 2015 to August 2016. Patients were randomized to conventional or heparin treatment groups. Clinical outcome measured were healed wound size, pain scores and total consumption of analgesic medication required to relieve pain. Safety of the treatment and adverse events were also measured RESULTS: Out of 66 patient included in study mean (SD) age of participants was 27 (10) years, of which 59% were males. Mean (SD) TBSA burn was 14% (3) [23 (35%) had SPTB, and 43 (65%) had DPTB]. The burn injury was caused by flames in 68% and by hot liquids in 32% patients. There was no statistically significant difference in distribution of patients according to age, gender, TBSA burn, etiology or depth of burns in the two treatment groups. As compared to conventional treatment group, heparin treatment group had significantly better outcomes. Number of days needed for wound healing was significantly lower in the heparin group than the conventional group (SPTB 14±1 vs. 20±4 days; P-value <0.000 and for DPTB, 15±3 vs. 19±2 days; P-value <0.003). Mean pain score was also lower in the heparin group (for both SPTB and DPTB 3±1 vs. 7±1; P-value <0.000). Similarly, total consumption of analgesic medication was significantly less in the heparin group (53±27 vs. 119±15mg; P-value <0.000 for SPTB and 46±6 vs. 126±12mg; P-value <0.000 for DPTB). In both groups, no patient had wound infection, skin necrosis, leucopenia, thrombocytopenia, worsening renal function, or abnormal liver enzymes CONCLUSION: Treatment of second degree or partial thickness burns (PTB) with topical heparin is superior to conventional treatment in terms of wound healing as well as for pain control. The treatment with topical heparin is well-tolerated and is without higher adverse effects.

Classification of burn injury using Raman spectroscopy and optical coherence tomography: An ex-vivo study on porcine skin

Accurate depth assessment of burn wounds is a critical task to provide the right treatment and care. Currently, laser Doppler imaging is able to provide better accuracy compared to the standard clinical evaluation. However, its clinical applicability is limited by factors like scanning distance, time, and cost. Precise diagnosis of burns requires adequate structural and functional details. In this work, we evaluated the combined potential of two non-invasive optical modalities, optical coherence tomography (OCT) and Raman spectroscopy (RS), to identify degrees of burn wounds (superficial partial-thickness (SPT), deep partial-thickness (DPT), and full-thickness (FT)). OCT provides morphological information, whereas, RS provides biochemical aspects. OCT images and Raman spectra were obtained from burns created on ex-vivo porcine skin. Algorithms were developed to segment skin region and extract textural features from OCT images, and derive spectral wave features from RS. These computed features were fed into machine learning classifiers for categorization of burns. Histological results obtained from trichrome staining were used as ground-truth. The combined performance of RS-OCT reported an overall average accuracy of 85% and ROC-AUC=0.94, in distinguishing the burn wounds. The significant performance on ex vivo skin motivates to assess the feasibility of combined RS-OCT in in vivo models.