Pedicled Chimeric Perforator Flap Based on Inferior Gluteal Vessel Axis for the Reconstruction of Stage-Four Primary Ischial Pressure Sores—A New Design

Background “Subfascial void reconstruction” in ischial pressure sores (IPSs) goes a long way in the amelioration of the common complications like persistent drainage, infection, wound dehiscence, and late recurrence. No locoregional flaps suffice this requirement. So we have designed a chimeric pedicled flap based on the inferior gluteal vessel axis (IGVA) perforators with two tissue components: (1) Pacman-style fasciocutaneous flap on a perforator and (2) gluteus maximus muscle (inferior portion) on another independent perforator. Aim and Methods After confirming the feasibility of novel design of chimeric pedicled IGVA perforator flap with cadaver study, we embarked on the clinical study with this chimeric flap. In this prospective cohort study, the study and the control existed in the same patient so that the biological factors affecting the wound healing would be the same. Results Twenty-one patients were included whose mean age was 39 years. Late recurrence occurred in one patient (4.8%) of chimeric flap while the control group (who had undergone conventional reconstruction) had recurrence in 11 patients (52.4%). On assessment with overall institutional score, grade A was observed in 18 patients of the chimeric IGVA flap group (p < 0.045), and in only 3 patients of the control group. Conclusions This anatomically construed flap, a new addendum in the armamentarium of reconstruction of IPSs, with its potential to congruently fill the ischiogluteal subfascial void may provide a lasting solution for preventing recurrences.

Collateral Vessels Have Unique Endothelial and Smooth Muscle Cell Phenotypes

Collaterals are unique blood vessels present in the microcirculation of most tissues that, by cross-connecting a small fraction of the outer branches of adjacent arterial trees, provide alternate routes of perfusion. However, collaterals are especially susceptible to rarefaction caused by aging, other vascular risk factors, and mouse models of Alzheimer’s disease—a vulnerability attributed to the disturbed hemodynamic environment in the watershed regions where they reside. We examined the hypothesis that endothelial and smooth muscle cells (ECs and SMCs, respectively) of collaterals have specializations, distinct from those of similarly-sized nearby distal-most arterioles (DMAs) that maintain collateral integrity despite their continuous exposure to low and oscillatory/disturbed shear stress, high wall stress, and low blood oxygen. Examination of mouse brain revealed the following: Unlike the pro-inflammatory cobble-stoned morphology of ECs exposed to low/oscillatory shear stress elsewhere in the vasculature, collateral ECs are aligned with the vessel axis. Primary cilia, which sense shear stress, are present, unexpectedly, on ECs of collaterals and DMAs but are less abundant on collaterals. Unlike DMAs, collaterals are continuously invested with SMCs, have increased expression of Pycard, Ki67, Pdgfb, Angpt2, Dll4, Ephrinb2, and eNOS, and maintain expression of Klf2/4. Collaterals lack tortuosity when first formed during development, but tortuosity becomes evident within days after birth, progresses through middle age, and then declines—results consistent with the concept that collateral wall cells have a higher turnover rate than DMAs that favors proliferative senescence and collateral rarefaction. In conclusion, endothelial and SMCs of collaterals have morphologic and functional differences from those of nearby similarly sized arterioles. Future studies are required to determine if they represent specializations that counterbalance the disturbed hemodynamic, pro-inflammatory, and pro-proliferative environment in which collaterals reside and thus mitigate their risk factor-induced rarefaction.

Preparation of Vessel Shapes to Analytical Study (Theses were published on 1988)

Theses contain a concise statement of main stages of preparation of earthenware vessels obtained from archeological excavations for analytical study. These stages include: 1. methods of photographic fixation of vessel shapes; 2. determination of vessel axis location and reconstruction of vessel’s average contour by way of asymmetry elimination; and 3. separation of vessel functional and simple, elementary parts, and determination of skeletons and covers of functional parts in vessel shapes’ structure.

Multiple Hidden Markov Model for Pathological Vessel Segmentation

One of the obstacles that prevent the accurate delineation of vessel boundaries is the presence of pathologies, which results in obscure boundaries and vessel-like structures. Targeting this limitation, we present a novel segmentation method based on multiple Hidden Markov Models. This method works with a vessel axis + cross-section model, which constrains the classifier around the vessel. The vessel axis constraint gives our method the potential to be both physiologically accurate and computationally effective. Focusing on pathological vessels, we reap the benefits of the redundant information embedded in multiple vessel-specific features and the good statistical properties coming with Hidden Markov Model, to cover the widest possible spectrum of complex situations. The performance of our method is evaluated on synthetic complex-structured datasets, where we achieve a 91% high overlap ratio. We also validate the proposed method on a real challenging case, segmentation of pathological abdominal arteries. The performance of our method is promising, since our method yields better results than two state-of-the-art methods on both synthetic datasets and real clinical datasets.

Axis-Guided Vessel Segmentation Using a Self-Constructing Cascade-AdaBoost-SVM Classifier

One major limiting factor that prevents the accurate delineation of vessel boundaries has been the presence of blurred boundaries and vessel-like structures. Overcoming this limitation is exactly what we are concerned about in this paper. We describe a very different segmentation method based on a cascade-AdaBoost-SVM classifier. This classifier works with a vessel axis + cross-section model, which constrains the classifier around the vessel. This has the potential to be both physiologically accurate and computationally effective. To further increase the segmentation accuracy, we organize the AdaBoost classifiers and the Support Vector Machine (SVM) classifiers in a cascade way. And we substitute the AdaBoost classifier with the SVM classifier under special circumstances to overcome the overfitting issue of the AdaBoost classifier. The performance of our method is evaluated on synthetic complex-structured datasets, where we obtain high overlap ratios, around 91%. We also validate the proposed method on one challenging case, segmentation of carotid arteries over real clinical datasets. The performance of our method is promising, since our method yields better results than two state-of-the-art methods on both synthetic datasets and real clinical datasets.

The Propeller Concept Applied to Free Flaps and the Proposal of a “Clock Flap” Nomenclature

Background It is a common experience for reconstructive surgeons to feel the necessity for large flaps and minimal donor-site morbidity at the same time. In the reported cases where we felt this call intraoperatively, we have met our need by applying the “propeller concept” to fasciocutaneous or composite flaps, separating and rotating its different tissue components. Methods We present a series of five cases in which we separated and rotated diversely fascial and cutaneous components of free perforator flaps to enhance the extension of the flap or to tailor it better on the tissue gap for optimal functional and aesthetic results. We also propose a simple nomenclature system for rotation angles' definition, summarized as the “clock flap” classification, where the different components of the flap represent the arms of a clock which has the main vessel axis on the 12–6 line. Results All reconstructive procedures succeeded with only minor complications. No partial failure due to vessel rotations was noticed. Conclusion Applying “propeller style” rotations to different components of free flaps seems to be a safe procedure which may help maximize flap performance in terms of coverage of the recipient site, while minimizing scars and impairment of the donor site. Also, the proposed nomenclature gives the opportunity to record and compare surgical procedures for statistical analysis.

IONTOVÁ VÝMĚNA V POČÁTEČNÍCH STÁDIÍCH INTERAKCE ŽIVEC–VODA

The sample of perthitic alkali feldspar (62.5 wt. % of KAlSi3O8 and 37.5 wt. % of albite, Na0,996Ca0,004Al1,004Si2,996O8) was dissolved in a special stirred batch reactor (polyethylene vessel of 5 liter volume situated horizontally and rotating at few rotations per hour). The reactor was opened to atmosphere (log PCO2 ~ -3.5) through the mouth at the vessel axis. During the experiment, pH was monitored by pH-meter with combined glass electrode. Solutions were analyzed for Si, Al (spectrophotometry), K, Na (flame AAS), and Ca (ICP-OES). The results showed a fast preferential leaching of alkaline cations with respect to both Al and Si during the early stages of experiment that was diminishing during more advanced stages of the experiment. The released cations exceeded the consumed H+ ions by the range of two up to four magnitudes. The preponderance of cations over H+ ions was especially apparent during few initial days, when the buffering by atmospheric CO2 was insufficient. Simulation of the process by the PHREEQC code covering the CO2 buffering indicated that system feldspar–water–CO2(g) was evolving near the equilibrium in open system during the period after 5th day of the experiment. The results suggested that the mechanism of feldspar dissolution during the initial stages of the process does not correspond to a simple ion exchange and that it is more complicated.

Automatic Extraction of Blood Vessels in the Retinal Vascular Tree Using Multiscale Medialness

We propose an algorithm for vessel extraction in retinal images. The first step consists of applying anisotropic diffusion filtering in the initial vessel network in order to restore disconnected vessel lines and eliminate noisy lines. In the second step, a multiscale line-tracking procedure allows detecting all vessels having similar dimensions at a chosen scale. Computing the individual image maps requires different steps. First, a number of points are preselected using the eigenvalues of the Hessian matrix. These points are expected to be near to a vessel axis. Then, for each preselected point, the response map is computed from gradient information of the image at the current scale. Finally, the multiscale image map is derived after combining the individual image maps at different scales (sizes). Two publicly available datasets have been used to test the performance of the suggested method. The main dataset is the STARE project’s dataset and the second one is the DRIVE dataset. The experimental results, applied on the STARE dataset, show a maximum accuracy average of around 94.02%. Also, when performed on the DRIVE database, the maximum accuracy average reaches 91.55%.