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8 result(s) for "Hellweg, Marc"
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Sensory Recovery After Free Muscle Flap Reconstruction—A Clinical Study of Protective and Discriminative Function of Free Gracilis and Latissimus Dorsi Muscle Flaps Without Neurotization
Background/Objectives: Free gracilis (GM) and latissimus dorsi muscle (LDM) flaps are reliable options for complex defect coverage, but long-term sensory outcomes remain underexplored. Sensory impairment, especially the loss of protective cutaneous sensation, increases the risk of injury, thermal damage, and ulceration in reconstructed areas. This study aimed to systematically assess multidimensional sensory recovery after free muscle flap (FMF) reconstruction. Methods: In a prospective single-center study, 94 patients (49 GM, 45 LDM) underwent standardized sensory testing following FMF transfer. Five modalities were evaluated: pressure detection (Semmes-Weinstein monofilaments), vibration perception, two-point discrimination (2PD), sharp–dull differentiation, and temperature differentiation. Measurements were compared to contralateral healthy skin (CHS). Subgroup analyses were performed by anatomical region (head, trunk, extremities). Results: All sensory modalities were significantly impaired in FMF compared to CHS (p < 0.0001). Mean pressure thresholds were markedly higher in FMF (248.8 g) versus CHS (46.8 g). Vibration perception scores were reduced (FMF 3.97 vs. CHS 5.31), and 2PD was significantly poorer (11.6 cm vs. 4.7 cm). Sharp–dull and thermal discrimination were largely absent in FMF (positivity rates < 20%), with 58.5% of patients demonstrating only deep pressure sensation (≥300 g). No significant differences were found between GM and LDM in most modalities, except for worse 2PD in GM. Subgroup analyses confirmed uniform deficits across all anatomical regions. Conclusions: FMFs without neurotization result in profound, persistent sensory deficits, particularly the loss of protective sensation. Clinically, fascio-cutaneous flaps with nerve coaptation should be considered in functionally critical regions. Future strategies should focus on neurotization techniques to enhance sensory recovery.
Analysis of Factors Determining Patient Survival after Receiving Free-Flap Reconstruction at a Single Center—A Retrospective Cohort Study
Background: Microsurgical tissue transfer revolutionized reconstructive surgery after extensive trauma, oncological resections, and severe infections. Complex soft tissue reconstructions are increasingly performed in multimorbid and elderly patients. Therefore, it is crucial to investigate whether these patients benefit from these complex procedures. Objective: To evaluate the outcome for multimorbid patients who underwent microsurgical soft tissue reconstruction and to identify potential risk factors that may increase mortality. Methods: This single-center study retrospectively analyzed prospectively collected data of patients receiving free gracilis (GM) or latissimus dorsi muscle (LDM) flap reconstruction between September 2017 and December 2021. Cases were divided into two groups (dead vs. alive), depending on patient survival. Patient demographics, comorbidities and medication, perioperative details, free flap outcome, as well as microcirculation were determined. Results: A total of 151 flaps (LDM, n = 67; GM, n = 84) performed in 147 patients with a mean age of 61.15 ± 17.5 (range 19–94) years were included. A total of 33 patients (22.45%) passed away during the study period. Deceased patients were significantly older (Alive: 58.28 ± 17.91 vs. Dead: 71.39 ± 11.13; p = 0.001), were hospitalized significantly longer (Alive: 29.66 ± 26.97 vs. Dead: 36.88 ± 15.04 days; p = 0.046) and suffered from cardiovascular (Alive: 36.40% vs. Dead: 66.70%; p = 0.002) and metabolic diseases (Alive: 33.90% vs. Dead: 54.50%; p = 0.031) more frequently, which corresponded to a significantly higher ASA Score (p = 0.004). Revision rates (Alive: 11.00% vs. Dead: 18.20%; p = 0.371) and flap loss (Alive: 3.39% vs. Dead: 12.12%; p = 0.069) were higher in patients that died by the end of the study period. Conclusions: Free flap transfer is safe and effective, even in multimorbid patients. However, patient age, comorbidities, preoperative ASA status, and medication significantly impact postoperative patient survival in the short- and mid-term and must, therefore, be taken into account in preoperative decision-making and informed consent.
To Shrink or Not to Shrink? An Objective Assessment of Free Gracilis Muscle Volume Change in Lower-Extremity Defect Reconstruction
Background: The use of free gracilis muscle flaps in reconstructive surgery of the lower leg is common practice to cover defects. However, there is still a lack of understanding of the morphometric changes that occur in the transferred muscle and area of interest over time, particularly the characteristic volume decrease that is observed over the course of the first year. This study aimed to assess volume changes in patients with free gracilis muscle flap reconstruction following infection, trauma, or malignancies of the lower extremity. Methods: Three-dimensional surface imaging was performed intraoperatively after 2 weeks, 6 months, and 12 months with the Vectra H2 system. A total of 31 patients were included in this study and analyzed. Results: There was an average volume increase of 146.67 ± 29.66% 2 weeks after reconstruction. Compared to this volume increase, there was a reduction of 108.44 ± 13.62% after 12 months (p < 0.05). Overall, we found a shrinkage to 85.53 ± 20.14% of the intraoperative baseline volume after 12 months. Conclusions: The use of non-invasive 3D surface imaging is a valuable tool for volume monitoring after free flap reconstruction of the lower extremity. The free gracilis muscle flap undergoes different phases of volume change over the first year, with the greatest influence on overall change being the development and decongestion of edema. Precise initial surgical tailoring is crucial for optimal long-term functional and cosmetic results.
Monitoring the hydrolysis of toxic organophosphonate nerve agents in aqueous buffer and in bicontinuous microemulsions by use of diisopropyl fluorophosphatase (DFPase) with (1)H- (31)P HSQC NMR spectroscopy
The enzyme diisopropyl fluorophosphatase (DFPase, EC 3.1.8.2) from the squid Loligo vulgaris effectively catalyzes the hydrolysis of diisopropyl fluorophosphate (DFP) and a number of organophosphorus nerve agents, including sarin, soman, cyclosarin, and tabun. Until now, determination of kinetic data has been achieved by use of techniques such as pH-stat titration, ion-selective electrodes, and a recently introduced method based on in situ Fourier-transform infrared (FTIR) spectroscopy. We report the use of 1D (1)H-(31)P HSQC NMR spectroscopy as a new method for real-time quantification of the hydrolysis of toxic organophosphonates by DFPase. The method is demonstrated for the agents sarin (GB), soman (GD), and cyclosarin (GD) but can also be used for V-type nerve agents, for example VX. Besides buffered aqueous solutions the method was used to determine enzymatic activities in a biodiesel-based bicontinuous microemulsion that serves as an example of complex decontamination media, for which other established techniques often fail. The method is non-invasive and requires only limited manual handling of small volumes of liquid (700 microL), which adds to work safety when handling highly toxic organophosphorus compounds. Limits of detection are slightly below 100 micromol L(-1) on a 400 MHz spectrometer with 16 FIDs added for a single time frame. The method is not restricted to DFPase but can be used with other phosphotriesterases, for example paraxonase (PON), and even reactive chemicals, for example oximes and other nucleophiles, as long as the reaction components are compatible with the NMR experiment.
The DFPase from Loligo vulgaris in sugar surfactant-based bicontinuous microemulsions: structure, dynamics, and enzyme activity
The enzyme diisopropyl fluorophosphatase (DFPase) from the squid Loligo vulgaris is of great interest because of its ability to catalyze the hydrolysis of highly toxic organophosphates. In this work, the enzyme structure in solution (native state) was studied by use of different scattering methods. The results are compared with those from hydrodynamic model calculations based on the DFPase crystal structure. Bicontinuous microemulsions made of sugar surfactants are discussed as host systems for the DFPase. The microemulsion remains stable in the presence of the enzyme, which is shown by means of scattering experiments. Moreover, activity assays reveal that the DFPase still has high activity in this complex reaction medium. To complement the scattering experiments cryo-SEM was also employed to study the microemulsion structure.
Monitoring the hydrolysis of toxic organophosphonate nerve agents in aqueous buffer and in bicontinuous microemulsions by use of diisopropyl fluorophosphatase with ¹H-sup.31P HSQC NMR spectroscopy
The enzyme diisopropyl fluorophosphatase (DFPase, EC 3.1.8.2) from the squid Loligo vulgaris effectively catalyzes the hydrolysis of diisopropyl fluorophosphate (DFP) and a number of organophosphorus nerve agents, including sarin, soman, cyclosarin, and tabun. Until now, determination of kinetic data has been achieved by use of techniques such as pH-stat titration, ion-selective electrodes, and a recently introduced method based on in situ Fourier-transform infrared (FTIR) spectroscopy. We report the use of 1D ¹H-[sup.31]P HSQC NMR spectroscopy as a new method for real-time quantification of the hydrolysis of toxic organophosphonates by DFPase. The method is demonstrated for the agents sarin (GB), soman (GD), and cyclosarin (GD) but can also be used for V-type nerve agents, for example VX. Besides buffered aqueous solutions the method was used to determine enzymatic activities in a biodiesel-based bicontinuous microemulsion that serves as an example of complex decontamination media, for which other established techniques often fail. The method is non-invasive and requires only limited manual handling of small volumes of liquid (700 µL), which adds to work safety when handling highly toxic organophosphorus compounds. Limits of detection are slightly below 100 µmol [L.sup.-1] on a 400 MHz spectrometer with 16 FIDs added for a single time frame. The method is not restricted to DFPase but can be used with other phosphotriesterases, for example paraxonase (PON), and even reactive chemicals, for example oximes and other nucleophiles, as long as the reaction components are compatible with the NMR experiment. Keywords Phosphotriesterases * Enzymes * Nerve agents * NMR * DFPase * Hydrolases
Monitoring the hydrolysis of toxic organophosphonate nerve agents in aqueous buffer and in bicontinuous microemulsions by use of diisopropyl fluorophosphatase (DFPase) with ¹H-³¹P HSQC NMR spectroscopy
The enzyme diisopropyl fluorophosphatase (DFPase, EC 3.1.8.2) from the squid Loligo vulgaris effectively catalyzes the hydrolysis of diisopropyl fluorophosphate (DFP) and a number of organophosphorus nerve agents, including sarin, soman, cyclosarin, and tabun. Until now, determination of kinetic data has been achieved by use of techniques such as pH-stat titration, ion-selective electrodes, and a recently introduced method based on in situ Fourier-transform infrared (FTIR) spectroscopy. We report the use of 1D ¹H-³¹P HSQC NMR spectroscopy as a new method for real-time quantification of the hydrolysis of toxic organophosphonates by DFPase. The method is demonstrated for the agents sarin (GB), soman (GD), and cyclosarin (GD) but can also be used for V-type nerve agents, for example VX. Besides buffered aqueous solutions the method was used to determine enzymatic activities in a biodiesel-based bicontinuous microemulsion that serves as an example of complex decontamination media, for which other established techniques often fail. The method is non-invasive and requires only limited manual handling of small volumes of liquid (700 μL), which adds to work safety when handling highly toxic organophosphorus compounds. Limits of detection are slightly below 100 μmol L⁻¹ on a 400 MHz spectrometer with 16 FIDs added for a single time frame. The method is not restricted to DFPase but can be used with other phosphotriesterases, for example paraxonase (PON), and even reactive chemicals, for example oximes and other nucleophiles, as long as the reaction components are compatible with the NMR experiment. [graphic removed]
Environmental impact of integrating decentralized urine treatment in the urban wastewater management system: A comparative life cycle assessment
AbstractAs municipal wastewater treatment regulations become more stringent, integrating source-separated urine treatment into centralized urban wastewater management offers a ‘hybrid’ solution. However, it is not clear how the environmental impacts of such hybrid systems compare to highly efficient centralized wastewater treatment plants (WWTPs) with low N2O emissions and electricity use. In this study, a consequential life cycle assessment was used to compare the environmental impact of three urine hybrid wastewater treatment systems – which combine decentralized urine treatment with a highly efficient central WWTP – to a centralized WWTP treating mixed wastewater (baseline). The studied urine treatment systems include partial nitrification & distillation, struvite precipitation & stripping/scrubbing, and partial nitritation/anammox. Additionally, the contribution of urine alkalinization to the overall impact was quantified. The results show that at least one hybrid scenario showed a lower environmental impact in 8 out of the 10 assessed impact categories. Global warming potential and marine eutrophication were found to be higher than the baseline. Additionally, it was identified that urine alkalinization increased the environmental impact of the treatment system in 7 out of the 10 impact categories. A Pareto frontier analysis was developed to guide decision makers on where hybrid solutions could be used as a strategy to reduce global warming impacts of conventional WWTPs. It was realized that using N₂O emission factors of 75 WWTPs, 87% of centralized WWTPs had lower CO₂ emissions compared to partial nitrification & distillation, and 91% compared to partial nitritation/anammox hybrid solutions. However, at energy demands of 1 kWh/PE and 2 kWh/PE, both hybrid solutions showed lower emissions than all the studied WWTPs. The study highlights the potential of hybrid wastewater treatment solutions to address specific environmental challenges in wastewater management and a strategy to reduce global warming impacts in WWTPs with high N₂O emissions and electricity use.Figure Figure* Download figure* Open in new tabGraphical abstractCompeting Interest StatementThe authors have declared no competing interest.