Progressive Distortion Research Articles

Bone: a key aspect to understand phenomena in clinical hematology.

The bone marrow (BM) is located inside the bone. Now, it appears that bone tissue functionally communicates with the BM hematopoietic system. Osteoblast lineage cells serve as a part of the microenvironment for immature hematopoietic (stem/progenitor) cells. In contrast, mature hematopoietic cells such as neutrophils and macrophages play a critical role to regulate osteoblast activity. A progressive distortion of this precise inter-organ communication between hematopoietic and skeletal systems may lead to hematologic disorders. Recent studies have revealed that vitamin D receptor is a pivotal bridging molecule for this network and for the pathogenesis of myelofibrosis.

954 Evaluation of Reasons for Admission in Patients With Decompensated Cirrhosis and Their Burden on Health Care Costs and Mortality Over the Years: Nationwide Analysis

INTRODUCTION: Cirrhosis is considered the late stage irreversible sequela of progressive fibrosis and distortion of hepatic architecture. Patients with decompensated cirrhosis have significant morbidity and mortality and may present with signs of upper GI bleeding, ascites, confusion, and kidney injury. The aim of our study was to evaluate and report the trends for the most common causes of decompensation in patients with cirrhosis. METHODS: A retrospective cohort analysis was performed using the Nationwide Inpatient Sample (NIS) from 2007–2014. All patients with a diagnosis of cirrhosis, elective admission, and age greater than 18 years were included in our analysis. We evaluated those who had primary admission diagnosis for ascites, spontaneous bacterial peritonitis, hepatic encephalopathy, esophageal variceal bleeding, and hepatorenal syndrome (HRS). We evaluated the trends of mortality, the length of stay, and cost of hospitalization. RESULTS: Ascites, spontaneous bacterial peritonitis, hepatic encephalopathy, esophageal variceal bleeding, and HRS accounted for 44,614 admissions from 2007–2014 as a primary diagnosis. Mortality for HRS decreased from 36.59% to 24.05% (P < 0.001) from 2007 to 2014, representing average overall mortality of 30.32%. Furthermore, average length of stay (LOS) for spontaneous bacterial peritonitis went from 7.22 days to 6.42 days (P < 0.05). Average LOS went from 9.07 days to 7.88 days (P < 0.05) for hepatic encephalopathy. Average total charges of hospitalization went from $51,665 to $71,779 (P < 0.001) from 2007 to 2014 for hepatic encephalopathy. Average total charges of hospitalization went from $19,692 to $32,336 (P < 0.001) from 2007 to 2014 for ascites. Mortality for bleeding from esophageal varices increased from 5.21% to 6.11% (P < 0.001) from 2007 to 2014, representing average overall mortality of 5.59%. Average total charges of hospitalization went from $34,107 to $51,424 (P < 0.001) from 2007 to 2014 for hepatic encephalopathy. CONCLUSION: Admission for HRS represents approximately 30% overall mortality in patients with decompensated cirrhosis in our study. On the contrary, while the total mean charge for hospitalization increases, spontaneous bacterial peritonitis and hepatic encephalopathy has had significant decrease in LOS from 2007–2014. Clinicians should be vigilant for patients admitted for HRS as it represents high mortality. Further prospective studies are warranted to evaluate the causes for high mortality in decompensated cirrhosis.

A power law study of the edge influence on the perceived filling-in brightness magnitude

BackgroundEdge plays a special role in spatial perception and as well as in determining the brightness of a surface within borders. The aim of our study was to measure threshold brightness in different levels of edges thickness.MethodsSteven’s power law for circles modulating in luminance was estimated for 30 subjects (mean age 24 years, SD 3.3, 13 female). Stimuli were presented on the iMac display using the 11-bit graphic board and consisted of two circles of 3° of visual angle, separated by 10°. We tested 7 levels of Michelson contrast: 7, 8, 10, 15, 26, 50, and 100. Three edges filtering were tested (0.3, 0.8, and 1.5° of smoothing). The subjects’ task was to judge the brightness of the edge filtered circle compared with the circle of the hard edge which was considered the modulus and received an arbitrary level of 50, representing the amount of brightness perception. In each trial, the same contrast level was presented in both circles. Five judgments were performed for each contrast level in edge filtering.ResultsWe found an increase in the power law exponent as the increase of the edge filtering (for sigma of 0.3 = 0.43, sigma of 0.8 = 0.73, and sigma 1.5 = 0.97). All power function fitting had high correlation coefficients (r2 = .94, r2 = .95, r2 = .97, respectively to sigma 0.3, 0.8, and 1.5) passing to the model’s adhesion criteria.ConclusionsThere was a progressive distortion on the figure brightness perception as increasing the edge filtering suggesting the control of edges on the polarity of the overall brightness. Also, perceived brightness was increasingly veridical with increased filtering, approaching 1:1 correspondence at 1.5 sigmas.

Tip‐vortex breakdown of wind turbines subject to shear

AbstractSheared velocity profiles pervade all wind‐turbine applications, thus making it important to understand their effect on the wake. In this study, a single wind turbine is modeled using the actuator‐line method in the incompressible Navier–Stokes equations. The tip vortices are perturbed harmonically, and the growth rate of the response is evaluated under uniform inflow and a linear velocity profile. Whereas previous investigations of this kind were conducted in the rotating frame of reference, this study evaluates the excitation response in the fixed frame of reference, thus necessitating a frequency transformation. It is shown that increasing the shear decreases the spatial growth rate in the upper half of the wake while increasing it in the lower half. When scaled with the local tip vortex parameters, the growth rate along the entire azimuth collapses to a single value for the investigated wavenumbers. We conclude that even though the tip‐vortex breakdown is asymmetric in sheared flow, the scaled growth rates follow the behavior of axisymmetric helical vortices. An excitation amplitude reduction by an order of magnitude extends the linear growth region of the wake by one radius for uniform inflow. In the sheared setup, the linear growth region is extended further in the top half than in the bottom half because of the progressive distortion of the helical tip vortices. An existing model to determine the stable wake length was shown to be in close agreement with the observed numerical results when adjusted for shear.

Surgery for idiopathic epiretinal membrane

Background Epiretinal membrane is an abnormal sheet of avascular fibrocellular tissue that develops on the inner surface of the retina. Epiretinal membrane can cause impairment of sight as a consequence of progressive distortion of retinal architecture. Objectives To determine the effects of surgery compared to no intervention for epiretinal membrane. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE Ovid, Embase Ovid, ISRCTN registry, US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). There were no restrictions to language or year of publication. The databases were last searched on 20 May 2020. Selection criteria We included randomised controlled trials (RCTs) assessing surgical removal of idiopathic epiretinal membrane compared to placebo, no treatment or sham treatment. Paired or within-person studies were included, as well as those where both eyes of a single participant were treated. Data collection and analysis We used standard methods expected by Cochrane, and assessed certainty using the GRADE system. We considered the following five outcome measures: mean change in best corrected visual acuity (BCVA) in the study eye between baseline (before randomisation), 6 months and 12 months later; proportion of people with a gain of 0.3 logMAR or more of visual acuity in the study eye as measured by a logMAR chart at a starting distance of 4 m at 6 months and 12 months after randomisation; proportion of people with a loss of 0.3 logMAR or more of visual acuity in the study eye as measured by a logMAR chart at a starting distance of 4 m at 6 months and 12 months after randomisation; mean quality of life score at 6 months and 12 months following surgery, measured using a validated questionnaire; and any harm identified during follow-up. Main results We included one study in the review. This was a RCT including 53 eyes of 53 participants with mild symptomatic epiretinal membrane and BCVA of 65 or more Early Treatment Diabetic Retinopathy Study (ETDRS) letters. Participants were randomly allocated to immediate surgery or to watchful waiting with deferred surgery if indicated by evidence of disease progression. The study was limited by imprecision owing to the small number of participants and was at some risk of bias owing to inconsistencies in the time points for outcome assessment and in the management of lens opacity. At 12 months, the visual acuity in the immediate surgery group was higher by a mean of 2.1 (95% confidence interval (CI) -2.0 to 6.2 ETDRS letters; 53 participants; low-certainty evidence) than the watchful waiting/deferred surgery group. The evidence of the effect of immediate surgery on gains of 0.3 logMAR or more of visual acuity is very uncertain (risk ratio (RR) 0.55, 95% CI 0.06 to 4.93; 53 participants; very low-certainty evidence). At 12 months, no participant in either group sustained a loss of 0.3 logMAR or more of visual acuity (53 participants; low-certainty evidence). The included study did not measure quality of life. At 12 months, no serious adverse event was identified in any participant. One participant developed chronic minimal cystoid macular oedema following immediate surgery (53 participants; low-certainty evidence). Authors' conclusions We found no RCT that directly investigated the effect of surgery compared to no intervention. For severe disabling epiretinal membrane, the lack of a RCT comparing surgery to no intervention may reflect evidence from non-randomised studies in favour of surgery; a RCT may be considered unnecessary and ethically unacceptable because a superior effect of surgery is widely accepted. For mild symptomatic epiretinal membrane, however, the value of surgery is uncertain. Low-certainty evidence from this review suggests that watchful waiting or deferred surgery may offer outcomes as favourable as immediate surgery. However, this finding needs to be confirmed in further RCTs with appropriate statistical power, masking of treatment allocation, consistent management of cataract, and measurement of outcomes including patient-reported quality of life over a more extended time frame.

Distortion evaluation method for the progressive addition lens–eye system

Distortion is one of the most significant defects in image optical systems. Herein, a method for comprehensively evaluating progressive addition spectacle lenses based on the modulation transfer function (MTF) and distortion of the lens–eye system is proposed. A lens–eye system is established, and the parameters of the system were simulated and measured simultaneously. The human eye model was compared with and without progressive addition lenses to obtain the image quality of the lenses. It was observed that eyes with different diopters and different lens designs show different trends; however, good improvement was observed in all cases after progressive addition lens correction. In terms of image clarity and deformation, the distant field was caused by a negative distortion value, the near area was caused by a positive distortion value. and the optical distortion was found to be proportional to the diopter. Moreover, the progressive corridor distortion value was minimal. With a larger field of view, the distortion of the lens became larger; thus, when an object was viewed through the lens, large distortion was observed at the edges.

Early history of nonlinear acoustics: Waveform distortion, disaster, and redemption

The first (although slightly incorrect) wave equations for finite-amplitude sound in lossless fluids were obtained independently by Euler in 1759 and Lagrange in 1760. Poisson (1808) provided the first major breakthrough with his exact solution for progressive waves of finite amplitude in a lossless gas. Although a far-reaching result, the progressive waveform distortion (and disastrous consequences) implied by his solution went unrecognized for 40 years. Challis (1848) showed that the Poisson solution is not single valued but did not understand why. Stokes (1848) provided the why. He saw that the Poisson waveform distorts as the wave travels, eventually threatening to become multivalued. He postulated that a discontinuity (shock) develops to avoid waveform overturning. He also saw that viscosity (not accounted for by Poisson) would prevent true discontinuities. Earnshaw (1860) and Riemann (1860) cleaned up plane waves in lossless gases. However, how to predict propagation after shocks form? Rankine (1870) and Hugoniot (1887, 1889) provided the first solutions for propagation when dissipation is included. These were the first steps toward redemption. The curtain rang down on this era of nonlinear acoustics with the excellent papers in 1910 by Rayleigh and Taylor on steady shocks in a thermoviscous fluid.

Orientational Ordering, Locking-in, and Distortion of CH4 Molecules in Methane Hydrate III under High Pressure

We investigate the effects of high pressure on the reorientational and vibrational dynamics of methane molecules embedded in methane hydrate III—the stable form of methane for pressures above 2 GPa at room temperature—by combining high-pressure Raman spectroscopy with ab initio simulations including nuclear quantum effects. We observe a clear evolution of the system from a gas-filled ice structure, where methane molecules occupy the channels of the ice skeleton and rotate almost freely, to a CH4:D2O compound where methane rotations are hindered, and methane and water dynamics are tightly coupled. The gradual orientational ordering of the guest molecules results in a complete locking-in at approximately 20 GPa. This happens along with a progressive distortion of the guest molecules. Finally, as pressure increases beyond 20 GPa, the system enters a strong mode coupling regime where methane guests and water hosts dynamics are intimately paired.

Burst-Like Transcription of Mutant and Wildtype MYH7-Alleles as Possible Origin of Cell-to-Cell Contractile Imbalance in Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) has been related to many different mutations in more than 20 different, mostly sarcomeric proteins. While development of the HCM-phenotype is thought to be triggered by the different mutations, a common mechanism remains elusive. Studying missense-mutations in the ventricular beta-myosin heavy chain (β-MyHC, MYH7) we hypothesized that significant contractile heterogeneity exists among individual cardiomyocytes of HCM-patients that results from cell-to-cell variation in relative expression of mutated vs. wildtype β-MyHC. To test this hypothesis, we measured force-calcium-relationships of cardiomyocytes isolated from myocardium of heterozygous HCM-patients with either β-MyHC-mutation Arg723Gly or Arg200Val, and from healthy controls. From the myocardial samples of the HCM-patients we also obtained cryo-sections, and laser-microdissected single cardiomyocytes for quantification of mutated vs. wildtype MYH7-mRNA using a single cell RT-qPCR and restriction digest approach. We characterized gene transcription by visualizing active transcription sites by fluorescence in situ hybridization of intronic and exonic sequences of MYH7-pre-mRNA. For both mutations, cardiomyocytes showed large cell-to-cell variation in Ca++-sensitivity. Interestingly, some cardiomyocytes were essentially indistinguishable from controls what might indicate that they had no mutant β-MyHC while others had highly reduced Ca++-sensitivity suggesting substantial fractions of mutant β-MyHC. Single-cell MYH7-mRNA-quantification in cardiomyocytes of the same patients revealed high cell-to-cell variability of mutated vs. wildtype mRNA, ranging from essentially pure mutant to essentially pure wildtype MYH7-mRNA. We found 27% of nuclei without active transcription sites which is inconsistent with continuous gene transcription but suggests burst-like transcription of MYH7. Model simulations indicated that burst-like, stochastic on/off-switching of MYH7 transcription, which is independent for mutant and wildtype alleles, could generate the observed cell-to-cell variation in the fraction of mutant vs. wildtype MYH7-mRNA, a similar variation in β-MyHC-protein, and highly heterogeneous Ca++-sensitivity of individual cardiomyocytes. In the long run, such contractile imbalance in the myocardium may well induce progressive structural distortions like cellular and myofibrillar disarray and interstitial fibrosis, as they are typically observed in HCM.

Density functional theory based interfacial studies of ABO3/SrTiO3 (A = La, Y, Sc, B = Al, Ga) and its relation to polar catastrophe

We have studied the density functional theory of epitaxially strained ABO3 (A = La, Y, Sc, B = Al, Ga) films on SrTiO3 (001) crystals with SrO- and TiO-terminations to investigate polar catastrophe induced by the epitaxial thin film growth. Interfacial polar nature of the strained films depends on the type of cations. While lanthanum based perovskite films produces polarity based on the ionic nature of interfacial atoms, the smaller cations show rather opposite polarities arising from progressive ferroelectric structural distortion acting opposite to the polar nature of cation ions.

Latest Developments in Corneal Surgery

Keratoconus is a disease characterised by progressive thinning, bulging and distortion of the cornea. Corneal transplantation (keratoplasty), is the standard of care for severe disease, but is associated with risks such as rejection of the transplanted cornea. Collagen cross-linking (CXL) is a relatively new conservative approach to strengthen corneal tissue by reforming new covalent bonds. In an expert interview, Leopoldo Spadea of the University of Rome, Italy, discusses recent advances in keratoplasty and CXL.

Role of defectivity on the crystallography of martensitic transformations in Ti50Ni40Cu10: an XRD investigation

Abstract Martensitic transformations in Ni50Ti40Cu10 are well known to proceed with a two-step process, from B2 austenite to monoclinic B19′ with intermediate orthorhombic B19. These transformations can be readily followed by X-ray diffraction especially in solution heat-treated materials through split and distribution of the main diffraction lines, while peaks broadening and overlap make the transformations more difficult to be described in highly defective materials. The present study addresses the effect of defects and chemical inhomogeneities on the martensitic transformation, placing particular emphasis on the crystallography of the low temperature B19 to B19′ phase transition. Lattice strains proved to be a powerful tool to monitor the martensitic transformations: whereas a clear discontinuity is observed for the solution heat-treated sample, defects promote a continuous progressive distortion from B19 to B19′. Calorimetry and internal friction investigations were added as a reference to verify the occurrence of the transformations and define the corresponding temperatures.

Long-term cryopreservation of decellularised oesophagi for tissue engineering clinical application.

Oesophageal tissue engineering is a therapeutic alternative when oesophageal replacement is required. Decellularised scaffolds are ideal as they are derived from tissue-specific extracellular matrix and are non-immunogenic. However, appropriate preservation may significantly affect scaffold behaviour. Here we aim to prove that an effective method for short- and long-term preservation can be applied to tissue engineered products allowing their translation to clinical application. Rabbit oesophagi were decellularised using the detergent-enzymatic treatment (DET), a combination of deionised water, sodium deoxycholate and DNase-I. Samples were stored in phosphate-buffered saline solution at 4°C (4°C) or slow cooled in medium with 10% Me2SO at -1°C/min followed by storage in liquid nitrogen (SCM). Structural and functional analyses were performed prior to and after 2 and 4 weeks and 3 and 6 months of storage under each condition. Efficient decellularisation was achieved after 2 cycles of DET as determined with histology and DNA quantification, with preservation of the ECM. Only the SCM method, commonly used for cell storage, maintained the architecture and biomechanical properties of the scaffold up to 6 months. On the contrary, 4°C method was effective for short-term storage but led to a progressive distortion and degradation of the tissue architecture at the following time points. Efficient storage allows a timely use of decellularised oesophagi, essential for clinical translation. Here we describe that slow cooling with cryoprotectant solution in liquid nitrogen vapour leads to reliable long-term storage of decellularised oesophageal scaffolds for tissue engineering purposes.

Non-random bonding of mono/divalent cations in mixed phosphate glasses

Incorporation of Sr to biocompatible Ca-phosphate glasses opened many possibilities for clinical applications. Transport properties relevant to the cation release in physiological conditions depend, among other factors, on the interaction with the PO4 forming groups. To understand these issues, three series of mixed glasses with mono (Na+) and divalent (Ca2+/Sr2+) cations were considered here: polyphosphates (0.57−x) Na2O∙x MO∙0.43 P2O5 (MCa, Sr; 0≤x≤0.57), and metaphosphate (0.50−x) Na2O∙x SrO∙0.50 P2O5 (0≤x≤0.50). Molar volumes and glass transition temperatures were analyzed as a function of the concentration of the alkaline earth. 31P and 23Na nuclear magnetic resonance techniques were applied to analyze local structure around phosphate groups and Na sites. As a function of the alkaline earth content, transitions in the evolution of properties (molar volume, glass transition temperature and 31P resonance of Q1 chain-end tetrahedra) were detected in the polyphosphate series. This behavior can be interpreted in terms of preferential bonding of the divalent cation to the oxygens in (PO3.5)2− anions (Q1), instead of (PO3)− (Q2). This non-statistical bonding to the available O is only possible up to a maximum concentration of the alkaline earth oxide (x=0.28), in good agreement with the observed break in properties of NaSr polyphosphate (x=0.30). A similar behavior seems plausible for Ca2+ in NaCa polyphosphate, but changes in the medium range order and progressive structural distortions induced by the stronger ion cause smooth variations of the molar volume. These findings may be relevant to understand the ion dissolution rates in biocompatible glasses, as the more hydrolysable Q2 groups concentrate the weaker cations, while the stronger Sr2+ or Ca2+ are located near chain-end Q1 groups.

Nonlinear Evolution of Short-wavelength Torsional Alfvén Waves

Abstract We analyze nonlinear evolution of torsional Alfvén waves in a straight magnetic flux tube filled in with a low-β plasma, and surrounded with a plasma of lower density. Such magnetic tubes model, in particular, a segment of a coronal loop or a polar plume. The wavelength is taken comparable to the tube radius. We perform a numerical simulation of the wave propagation using ideal magnetohydrodynamics. We find that a torsional wave nonlinearly induces three kinds of compressive flows: the parallel flow at the Alfvén speed, which constitutes a bulk plasma motion along the magnetic field, the tube wave, and also transverse flows in the radial direction, associated with sausage fast magnetoacoustic modes. In addition, the nonlinear torsional wave steepens and its propagation speed increases. The latter effect leads to the progressive distortion of the torsional wave front, i.e., nonlinear phase mixing. Because of the intrinsic non-uniformity of the torsional wave amplitude across the tube radius, the nonlinear effects are more pronounced in regions with higher wave amplitudes. They are always absent at the axes of the flux tube. In the case of a linear radial profile of the wave amplitude, the nonlinear effects are localized in an annulus region near the tube boundary. Thus, the parallel compressive flows driven by torsional Alfvén waves in the solar and stellar coronae, are essentially non-uniform in the perpendicular direction. The presence of additional sinks for the wave energy reduces the efficiency of the nonlinear parallel cascade in torsional Alfvén waves.

Ordering effect on the mechanical, electronic and magnetic properties of the β-based non-canonical approximant phases: β-Al50Cu33Fe17, η-Al50Cu44Fe6 and φ-Al47.5Cu49.5Fe3

Using transmission electron microscopy and X-ray diffraction, we established that the ordered η1-Al50Cu44Fe6 and φ-Al47.5Cu49.5Fe3 (Fmm2) alloys with nano-sized domain structure are formed by slowly cooling, whereas β-solid solutions with a short-range order were found in quenched states. The φ′-modification which exhibits the additional long-period superstructure was also observed in Al47.5Cu49.5Fe3. The studies of low temperature magnetic susceptibility and heat capacity did not reveal any another phase transitions in these alloys. The indentation test showed that hardness and Young’s modulus consistently grow as β-Al50Cu33Fe17 → η1-Al50Cu44Fe6 → (φ+φ′)-Al47.5Cu49.5Fe3 and approach to those in icosahedral phase. The same trend in the Young’s modulus was obtained for alloys containing β-solid solution with a short-range order. Ab initio calculations, however, predicted the opposite tendency in cubic β-Al50Cu50−xFex with a decrease in x, which was explained by the weakening of the covalent Fe 3d – Al sp bonding. This discrepancy between the results for β- and ordered phases, we related to a crucial effect of ordering which is accompanied by a progressive distortion of cubic local structure in the series β-Al50Cu33Fe17 → η1-Al50Cu44Fe6 → φ-Al47.5Cu49.5Fe3. As we demonstrated for η-Al(Cu, Fe), these distortions lead to the strengthening of the both covalent Fe–Al and Cu–Al bonds and the higher modules.

Mesenchymal Stem Cell-Dependent Modulation of Liver Diseases.

Acute liver failure and cirrhosis display sequential and overlapping severe pathogenic processes that include inflammation, hepatocyte necrosis, and fibrosis, carrying a high mortality rate. Mesenchymal stem cells (MSCs) are a heterogeneous subset of stromal stem cells with immunonodulatory characteristics. MSCs are considered to act through multiple mechanisms to coordinate a dynamic, integrated response to liver inflammation and fibrosis, which prevents the progressive distortion of hepatic architecture. Accordingly, MSCs as well as their products have been investigated as a novel therapeutic approach for the treatment of inflammatory and fibrotic liver diseases.In this review, we highlight the current findings on the MSC-based modulation of liver inflammation and fibrosis, and the possible use of MSCs in the therapy of immune-mediated liver pathology. We briefly describe the cellular and molecular mechanisms involved in MSC-dependent modulation of cytokine production, phenotype and function of liver infiltrated inflammatory cells and compare effects of engrafted MSCs versus MSC-generated conditioned medium (MSC-CM) in the therapy of acute liver injury. In order to elucidate therapeutic potential of MSCs and their products in modulation of chronic liver inflammation and fibrosis, we present the current findings regarding pathogenic role of immune cells in liver fibrosis and describe mechanisms involved in MSC-dependent modulation of chronic liver inflammation with the brief overview of on-going and already published clinical trials that used MSCs for the treatment of immune mediated chronic liver diseases. The accumulating evidence shows that MSCs had a significant beneficial effect in the treatment of immune-mediated liver diseases.

Rectal prolapse traumatizes rectal neuromuscular microstructure explaining persistent rectal dysfunction.

PurposeInternal rectal prolapse is common and correlates with age. It causes a plug-like physical obstruction and is a major cause of defecation disorder. The progressive distortion of the prolapsing rectum likely causes secondary defects in the rectal wall, which may exacerbate rectal dysfunction. We undertook a prospective observational study to detect and quantify the neurologic and histopathologic changes in the rectal wall.MethodsWe examined dorsal and ventral rectal wall specimens from consecutive patients with internal rectal prolapse undergoing stapled transanal rectal resection (STARR). We subjected specimens to histopathologic and neuropathologic assessment, including immunohistochemistry. We also recorded patients’ clinical and demographic characteristics and sought correlations between these and the pathologic findings.ResultsWe examined 100 specimens. The severity of rectal prolapse and the extent of descent of the perineum correlated significantly with age. Concomitant hemorrhoidal prolapse was noted in all male patients and in 79 % of female patients. Muscular and neuronal defects were detected in 94 and 90 % of the specimens, respectively. Only four specimens (4 %) were free of significant structural defects.ConclusionRectal prolapse traumatizes the rectum causing neuromuscular defects. The tissue trauma is due to shearing forces and ischemia caused by the intussusception. This initiates a self-reinforcing vicious circle of physical and functional obstruction, further impairing rectal evacuation and causing constipation and incontinence. The correlation between extent of prolapse and age suggests that internal rectal prolapse can be considered a degenerative disorder. Neural and motor defects in the wall of the rectum caused by rectal prolapse are likely irreversible.

Corneal surgery in keratoconus: which type, which technique, which outcomes?

Keratoconus is a disease characterized by progressive thinning, bulging, and distortion of the cornea. Advanced cases usually present with loss of vision due to high irregular astigmatism. A majority of these cases require surgical intervention. This review provides an update on the current treatment modalities of corneal surgery available for the management of advanced corneal ectasias.

Primary osteolysis syndromes: beware of difficult airway.

Primary osteolysis syndromes represent a number of rare conditions characterized by destruction and resorption of bone that is unrelated to neoplasia, infection, or trauma. To characterize the periprocedural course of patients with primary osteolysis syndrome undergoing procedures that require anesthesia care. The medical records database from our institution was searched from 1976 to 2013 to identify patients with primary osteolysis syndromes who received anesthesia care. We reviewed demographic characteristics, comorbidities, and perioperative course of patients with different forms of primary osteolysis. A systematic review of the literature was performed to identify reports describing the anesthetic management of patients with these conditions. We identified 11 patients with a primary osteolysis syndrome who received 111 anesthetics. The patients' ages at the time of surgery ranged from 3 to 62years. Difficult airway management was a common finding. On preoperative examination, difficulty with endotracheal intubation was predicted in 8 of 11 patients. Three patients had preexisting tracheostomies. One patient required multiple awake fiberoptic intubations. Another two patients where successfully intubated early in life via direct laryngoscopy, but eventually required awake fiberoptic intubations as the disease process caused progressive distortion of airway structures. Intraoperative complications were absent. In the postoperative period, three patients required prolonged mechanical ventilation due to airway swelling, respiratory failure, and infection. Airway management may be challenging in patients with primary osteolysis syndromes. Because the osteolytic process advances with aging and craniofacial dysmorphism may progressively worsen, the airway should always be reassessed before surgery with an appropriate strategy for potentially difficult intubation. In all patients with primary osteolysis, a potential for pathologic fracture must be considered and careful intraoperative positioning is warranted.