Investigating the Impact of Flap Overdesign on Viability.
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ABSTRACT:
SUBMITTER: Aherrera AS
PROVIDER: S-EPMC5553470 | biostudies-other | 2016 Apr
REPOSITORIES: biostudies-other
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Project description:PURPOSE:To evaluate protective effects of dexmedetomidine, calcitriol and their combination. METHODS:Forty Wistar-albino rats were divided into 4 groups; group of Sham (Group Sham); group of dexmedetomidine (Group DEX); group of calcitriol (Group CAL) and group of dexmedetomidineandcalcitriol (Group DEX-CAL). Photographic analysis was used for macroscopic analysis and perfusion analyses were evaluated by scintigraphy. Additionally, tissue malondialdehyde (MDA) and total oxidant status (TOS) and total antioxidant activity (TAS) were recorded and oxidative stress index (OSI) was calculated. Each flap was assessed by histopathology. RESULTS:Compared to Group Sham, the viable flap areas were higher in all treatment groups both by photographic image analyses and perfusion analyses (p<0.05). Group DEX-CAL had the highest viable flap percentage both in scintigraphic and photographic analyses; whereas Group Sham had the lowest viable flap percentage. Similarly, TAS and MDA levels were elevated and TOS levels were declined in all treatment groups compared to Group Sham (p<0.005). Histopathological analysis at flap demarcation zone confirmed neovascularization was significantly higher and edema, necrosis and inflammation were significantly lower in all treatment groups compared to Group Sham. CONCLUSION:The outcomes show that additional premedication with either dexmedetomidine or calcitriol or their combination reduces ischemia-reperfusion injury of flap area and show significant increase in the percentage of viable flap tissue.
| S-EPMC7531053 | biostudies-literature
Project description:BackgroundAccurate prediction of mastectomy skin flap viability is vital as necrosis causes significant morbidity, potentially compromising results and delaying oncological management. Traditionally assessed by clinical judgement, a more objective evaluation can be provided using intraoperative imaging modalities. This systematic review aimed to compare all intraoperative techniques for assessment of mastectomy flap viability.MethodsA systematic literature review was performed using MEDLINE and Embase databases. Primary outcomes reported included specificity, sensitivity and predictive values of each test, and mean rates of mastectomy flap necrosis and reoperation. Secondary outcomes included cost analysis.ResultsSome 18 studies were included. Designs were prospective cohort study (8), retrospective case series (4), prospective case series (3), retrospective case-control study (1), prospective pilot trial (1) and cost analysis study (1). The studies compared indocyanine green angiography (ICGA) (16 studies) and fluorescein dye angiography (FA) (3 studies) with clinical judgement. Sensitivity and specificity were highest for ICGA (5 studies) ranging from 38 to 100 and 68 to 91 per cent respectively. Both methods overpredicted necrosis. Mean rates of flap necrosis and reoperation decreased with ICGA (7·9 and 5·5 per cent respectively) and FA (3 and 0 per cent) compared with clinical judgement (19·4 and 12·9 per cent). Two studies were designed to define numerical parameters corresponding to perfusion using intraoperative techniques. Two studies performed a cost analysis for ICGA; one claimed a cost benefit and the other advocated its use in high-risk patients only.ConclusionICGA and FA are potentially useful tools for mastectomy flap assessment. However, the predictive accuracy is subject to the specific settings and model of equipment used. Current recommendations support their use in high-risk patients.
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Project description:Head and neck reconstructive surgeons have recently explored new perspectives in bone restoration using periosteum carrier flaps. Following this idea, we explored the possibility of harvesting a galeo-pericranial flap. The present work studies the vascular supply of the pericranial temporo-parietal region in order to assess the possibility of harvesting a galeo-pericranial flap based on the superficial temporalis vascularization. Anatomical dissections were performed at the Anatomical Institute of the University of Bologna on eight donor cadavers. Then we performed the harvesting of the flap in vivo on eight patients. We introduced augmented reality (AR) to facilitate anatomical visualisation during free flap harvesting. Augmented reality merges virtual and actual objects, allowing direct observation of patient anatomy and the surgical field. No post-operative major or minor complications occurred. We encountered no post-operative functional issues on the donor or recipient sites, and good clinical healing was observed in all patients. In conclusion, we believe that the galea-pericranium flap could represent a new donor site for the harvesting of a periosteum carrier flap.
| S-EPMC7408700 | biostudies-literature
Project description:ImportanceSmoking is a known risk to wound healing, but whether electronic cigarettes present the same risk remains unknown.ObjectiveTo evaluate the rate of flap necrosis in the e-cigarette vapor-exposed group and the unexposed control and to detect a difference in the rate of flap necrosis between the traditional cigarette smoke-exposed group and the unexposed control.Design, setting, and participantsFrom March 10, 2018, to May 4, 2018, a cohort study was conducted on 45 male Sprague-Dawley rats at Boston University School of Medicine. Each rat weighed approximately 100 g at the beginning of the study and was randomized to 1 of 3 groups: negative control (n = 15), experimental (exposed to e-cigarette vapor; n = 15), and positive control (exposed to traditional cigarette smoke; n = 15). Rats in the experimental and positive control groups were exposed to electronic cigarette vapor and traditional cigarette smoke in a smoking chamber for 30 minutes twice a day for 30 consecutive days. Levels of serum cotinine were monitored and maintained between 150 ng/mL and 200 ng/mL. After 30 days, random pattern dorsal skin flaps were raised.Main outcomes and measuresPercentage of flap necrosis for each group.ResultsAll 45 rats survived the surgical procedure and postoperative recovery, and all rats thrived and gained weight over the course of the study. The highest rate of flap necrosis was found in the positive control cohort, with a mean (SD) of 68.7% (8.6%), followed by the experimental cohort, with a mean (SD) of 65.9% (11.8%); the negative control cohort had the least amount of flap necrosis, with a mean (SD) of 50.8% (9.4%). The percentage of flap necrosis in the negative control rats (95% CI, 46.0-55.6; P < .001) was substantially lower than that for both the positive control rats (95% CI, 64.3-73.0; P < .001) and the experimental rats (95% CI, 59.9-71.8; P < .001). No statistically significant difference in flap necrosis was noted between the rats in the experimental cohort and the rats in the positive control cohort (95% CI, 59.9-71.8 vs 95% CI, 64.3-73.0; P = .46).Conclusions and relevanceSmoking and vaping appear to be equally detrimental to wound healing and to be associated with a statistically significant increase in flap necrosis compared with the unexposed group. The results suggest that vaping should not be seen as a better alternative to cigarette smoking in the context of wound healing.Level of evidenceNA.
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Project description:The development of novel polymer-based materials opens up possibilities for several novel applications, such as advanced wound dressings, bioinks for 3D biofabrication, drug delivery systems, etc. The aim of this study was to evaluate the viability of vascular and intestinal epithelial cells on different polymers as a selection procedure for more advanced cell-polymer applications. In addition, possible correlations between increased cell viability and material properties were investigated. Twelve polymers were selected, and thin films were prepared by dissolution and spin coating on silicon wafers. The prepared thin films were structurally characterized by Fourier transform infrared spectroscopy, atomic force microscopy, and goniometry. Their biocompatibility was determined using two epithelial cell lines (human umbilical vein endothelial cells and human intestinal epithelial cells), assessing the metabolic activity, cell density, and morphology. The tested cell lines showed different preferences regarding the culture substrate. No clear correlation was found between viability and individual substrate characteristics, suggesting that complex synergistic effects may play an important role in substrate design. These results show that a systematic approach is required to compare the biocompatibility of simple cell culture substrates as well as more complex applications (e.g., bioinks).
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Project description:The evidence for lower limb flap (LLF) training regimens is equivocal. The commonest cause of LLF failure is venous congestion. The aim of this study was to investigate whether venous congestion could be reduced by patient-led isometric calf contractions during flap training. A prospective clinical study was conducted using photospectroscopy and laser Doppler (Oxygen to See) to assess healthy limbs and LLF characteristics during flap training and isometric calf contractions. Tissue oxygen saturation, venous congestion, and blood flow were measured at rest, as well as during and after limb dangling and calf contraction exercises. In the acute postoperative period following LLF surgery, dependency markedly reduced superficial flow (-55.20% ± 19.17%), with a concurrent increase in venous congestion (33.80% ± 28.80%); supine isometric contractions improved superficial flow and reduced venous congestion from postoperative day 5. Contractions cause a significant increase in blood flow in the outpatient cohort (+84.40% ± 7.86%, P = 0.009), with a mean time since discharge of 14 weeks. Our data suggest patient-led isometric calf exercises are well tolerated and may reduce venous congestion in the acute phase. Progressive changes toward normal physiological function were demonstrated in the outpatient rehabilitation period. Incorporating calf exercises into LLF rehabilitation may allow longer periods of leg dependency, quicker recovery from surgery, and ultimately improve outcomes.
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Project description:Bacteria detection, counting and analysis is of great importance in several fields. When viability plays a major role in decision making, the counting of colony-forming units grown on agar plates remains the gold standard. However, because plate counts depend on the growth of the bacteria, it is a slow procedure and only works with culturable species. Impedance flow cytometry (IFC) is a promising technology for particle detection, counting and characterization. It relies on the perturbation of an electric field by particles flowing through a microfluidic channel. The perturbation is directly related to the electrical properties of the particles, and therefore provides information about their composition and structure. In this work we investigate whether IFC can be used to differentiate viable cells from inactivated cells. Our findings demonstrate that the specific viability state of the bacteria has to be considered, but that with proper characterization thresholds, IFC can be used to classify bacterial viability states. By using three different inactivation methods-ethanol, heat and autoclavation-we have been able to show that the impedance response of Escherichia coli depends on its viability state, but that the specific response depends on the inactivation method. With these findings we expect to be able to optimize IFC for more reliable bacteria detection and counting in the future.
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Project description:Flap endonuclease 1 (FEN1) is an important component of the intricate molecular machinery for DNA replication and repair. FEN1 is a structure-specific 5' nuclease that cleaves nascent single-stranded 5' flaps during the maturation of Okazaki fragments. Here, we review our research primarily applying single-molecule fluorescence to resolve important mechanistic aspects of human FEN1 enzymatic reaction. The methodology presented in this review is aimed as a guide for tackling other biomolecular enzymatic reactions by fluorescence enhancement, quenching, and FRET and their combinations. Using these methods, we followed in real-time the structures of the substrate and product and 5' flap cleavage during catalysis. We illustrate that FEN1 actively bends the substrate to verify its features and continues to mold it to induce a protein disorder-to-order transitioning that controls active site assembly. This mechanism suppresses off-target cleavage of non-cognate substrates and promotes their dissociation with an accuracy that was underestimated from bulk assays. We determined that product release in FEN1 after the 5' flap release occurs in two steps; a brief binding to the bent nicked-product followed by longer binding to the unbent nicked-product before dissociation. Based on our cryo-electron microscopy structure of the human lagging strand replicase bound to FEN1, we propose how this two-step product release mechanism may regulate the final steps during the maturation of Okazaki fragments.
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Project description:Many aspects of and factors required for DNA replication are conserved across all three domains of life, but there are some significant differences surrounding lagging-strand synthesis. In Archaea, a 5'-to-3' exonuclease, related to both bacterial RecJ and eukaryotic Cdc45, that associates with the replisome specifically through interactions with GINS was identified and designated GAN (for GINS-associated nuclease). Despite the presence of a well-characterized flap endonuclease (Fen1), it was hypothesized that GAN might participate in primer removal during Okazaki fragment maturation, and as a Cdc45 homologue, GAN might also be a structural component of an archaeal CMG (Cdc45, MCM, and GINS) replication complex. We demonstrate here that, individually, either Fen1 or GAN can be deleted, with no discernible effects on viability and growth. However, deletion of both Fen1 and GAN was not possible, consistent with both enzymes catalyzing the same step in primer removal from Okazaki fragments in vivo RNase HII has also been proposed to participate in primer processing during Okazaki fragment maturation. Strains with both Fen1 and RNase HII deleted grew well. GAN activity is therefore sufficient for viability in the absence of both RNase HII and Fen1, but it was not possible to construct a strain with both RNase HII and GAN deleted. Fen1 alone is therefore insufficient for viability in the absence of both RNase HII and GAN. The ability to delete GAN demonstrates that GAN is not required for the activation or stability of the archaeal MCM replicative helicase.IMPORTANCE The mechanisms used to remove primer sequences from Okazaki fragments during lagging-strand DNA replication differ in the biological domains. Bacteria use the exonuclease activity of DNA polymerase I, whereas eukaryotes and archaea encode a flap endonuclease (Fen1) that cleaves displaced primer sequences. RNase HII and the GINS-associated exonuclease GAN have also been hypothesized to assist in primer removal in Archaea Here we demonstrate that in Thermococcus kodakarensis, either Fen1 or GAN activity is sufficient for viability. Furthermore, GAN can support growth in the absence of both Fen1 and RNase HII, but Fen1 and RNase HII are required for viability in the absence of GAN.
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Project description: Not available
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