Morphological assessment of vascular anastomoses performed using high frequency electric welding / Evaluación morfológica de anastomosis vasculares realizada mediante soldadura eléctrica de alta frecuencia

SUMMARY: The studies of the properties of vascular structures and tissues during electric welding, in particular direct morphological changes in the blood vessel walls in the areas of welding processes, are of interest. Perforating veins, femoral veins, abdominal aorta, vena cava and porcine perforating veins of the limbs were used in this study. We performed end-to-end electric welding of the aorta, venous end-to-side electric welding, vein end-to-artery side arterial and venous welding, venous end-to-end electric welding, as well as arterial and venous lumen sealing.The results of histological studies showed the formation of a coagulated acellular protein matrix, represented by unorganized denatured protein fibrous structures. In the area of vascular tissue coagulation, lacunes were formed as a result of water evaporation from the biological tissue. In the perifocal area of the welded junction, cell reduction occurred without necrosis or charring. The data obtained confirm the safety of high frequency electric welding of the main vessels and the prospectfor clinical use of the studied techniques.

RESUMEN: Los estudios de las propiedades de las estructuras y tejidos vasculares durante la soldadura eléctrica son relevantes, en particular los cambios morfológicos directos en las paredes de los vasos sanguíneos en las áreas de los procesos de soldadura. En este estudio se utilizaron venas perforantes, venas femorales, parte abdominal de la aorta, vena cava y venas perforantes porcinas de los miembros. Realizamos soldadura eléctrica de extremo a extremo de la parte abdominal de la aorta, soldadura eléctrica de extremo a lado venosa, soldadura arterial y venosa de extremo a arteria del lado venoso, soldadura eléctrica de extremo a extremo venoso, así como lumen arterial y venoso. Los resultados de los estudios histológicos mostraron la formación de una matriz de proteína acelular coagulada, representada por estructuras fibrosas de proteínas desnaturalizadas no organizadas. Se formaron lagunas como resultado de la evaporación del agua del tejido biológico en el área de la coagulación del tejido vascular, En el área perifocal de la unión soldada, la reducción celular ocurrió sin necrosis ni carbonización. Los datos obtenidos confirman la seguridad de la soldadura eléctrica de alta frecuencia de los vasos principales y la perspectiva de uso clínico de estas técnicas.

Limitations of GD-EOB-DTPA-enhanced MRI: can clinical parameters predict suboptimal hepatobiliary phase?

AIM: To establish cut-off levels of the clinical parameters, which would predict suboptimal 30 minutes delayed hepatobiliary phase (HBP) with high specificity. MATERIALS AND METHODS: This retrospective study included patients with chronic liver disease who underwent hepatocellular carcinoma screening with Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) between 1 January 2011 and 30 November 2014. For each case, HBP was graded as adequate or suboptimal, based on Liver Image Reporting and Data System (LI-RADS) criteria. The following laboratory data obtained within 3 months of the MRI date was extracted: total bilirubin (TB), direct bilirubin (DB), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT), alkaline phosphatase (ALP), albumin, activated partial thromboplastin time (aPTT), and International normalised ratio (INR). Model For End-Stage Liver Disease (MELD) scores were calculated as 3.78×ln[TB] + 11.2×ln[INR] + 9.57×ln[creatinine] + 6.43. Receiver operating characteristic (ROC) curve analysis was used to establish cut-off values for predicting suboptimal HBP. RESULTS: Of 284 patients, 242 (85.2%) patients (91; 57.6% male) had an adequate HBP and 42 (14.8%) patients (13; 61.9% male) had suboptimal HBP, with mean ages of 58.5±9.7 years and 55±12.7 years, respectively (p=0.096). Areas under the ROC curve for predicting suboptimal HBP were 0.85 (95%CI 0.79-0.91) for the MELD score, 0.88 (95%CI 0.82-0.93) for TB, and 0.91 (95%CI 0.86-0.95) for DB. Accuracy, positive likelihood ratios and cut-off values for predicting suboptimal HBP were, respectively: 86.7% and 11.2 for the MELD score ≥16.7, 88.2% and 28.7 for TB ≥4.3 mg/dl, and 91.1% and 36.4 for DB ≥1.3 mg/dl. SGOT, SGPT, and ALP were not statistically significantly different between the groups. CONCLUSION: Cut-off levels of MELD score, DB, and TB can predict an suboptimal HBP with high accuracy. Prospective identification of patients with a high likelihood of an suboptimal HBP can help to avoid administering a more costly agent to patients who would not benefit from its unique properties.

Emergency department imaging: are weather and calendar factors associated with imaging volume?

AIM: To identify weather and calendar factors that would enable prediction of daily emergency department (ED) imaging volume to aid appropriate scheduling of imaging resources for efficient ED function. MATERIALS AND METHODS: Daily ED triage and imaging volumes for radiography, computed tomography (CT), and ultrasound were obtained from hospital databases for the period between January 2011 and December 2013 at a large tertiary urban hospital with a Level II trauma centre. These data were tabulated alongside daily weather conditions (temperature, wind and precipitation), day of week, season, and holidays. Multivariate analysis was performed. Pearson correlations were used to measure the association between number of imaging studies performed and ED triage volume. RESULTS: For every additional 50 triaged patients, the odds of having high (imaging volume ≥90th percentile) radiography, CT, and ultrasound volume increased by 4.3 times (p<0.001), 1.5 times (p=0.02), and 1.4 times (p=0.02), respectively. Tuesday was an independent predictor of high radiography volume (odds ratio=2.8) and Monday was an independent predictor of high CT volume (odds ratio=3.0). Weekday status was an independent factor increasing the odds of a high US volume compared to Saturday (odds ratios ranging from 5.6-9.8). Weather factors and other calendar variables were not independent predictors of high imaging volume. Using Pearson correlations, ED triage volume correlated with number of radiographs, CT, and ultrasound examinations with r=0.73, 0.37, and 0.41, respectively (p<0.0001). CONCLUSION: As ED triage volume was found to be the only factor associated with imaging volume for all techniques, analysis of predictors of ED triage volumes at a particular healthcare facility would be useful to determine imaging needs. Although calendar and weather factors were found to be minor or non-significant independent predictors of ED imaging utilisation, these may be important in influencing the actual number of ED triages.

[NERVOUS SYSTEM LESIONS ASSOCIATED WITH RELAPSING POLYCHONDRITIS: ANALYSIS OF ORIGINAL OBSERVATIONS].

Three clinical cases are described including two of relapsing polychondritis with lesions in the central and peripheral nervous system (one of long-standing aseptic lymphocytic meningitis and one of cranial neuropathy of 2, 5, 7, and 8 pairs) and the third case of the optic nerve lesion with amblyopia. The two former cases were successfully treated with high doses of corticosteroids, the third one with moderate doses of the same medications. The data from the current literature concerning variants of clinical manifestations, methods for diagnostics and treatment of neurologic manifestations of relapsing polychondritis are discussed.

[A rare combination of systemic scleroderma, sarcoidosis and psoriasis at advanced age].

We report a rare combination of systemic sclerosis, sarcoidosis, psoriatic arthritis and diverticulosis with severe complications in a 41-year-old male who has been treated by a rheumatologist since 10 years of age.

[RESTORATION OF TENDONS, USING ELECTRIC WELDING ­ A NEW STEP IN TRAUMATOLOGY].

Results of experimental investigations of operative treatment of the tendons traumatic injury, using additional to apparatus Patonmed­300 device of our construction, which have helped to perform a high­frequency welding of tendons, were presented. The advantages of a high frequency welding over existing operative procedures, using suture materials, were proved. Results of experimental investigations witness possibility to achieve improvement in the operative treatment result for traumatic injury of carpal tendons in clinical environment.

Improved parenchymal liver enhancement with extended delay on Gd-EOB-DTPA-enhanced MRI in patients with parenchymal liver disease: associated clinical and imaging factors.

AIM: To establish the effect of prolonged hepatobiliary phase (HBP) delay time on hepatic enhancement in patients with parenchymal liver disease (PLD). MATERIALS AND METHODS: Gadoxetate disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) examinations with HBP were obtained after 20- (HBP-20) and 30-minute (HBP-30) delays in patients with PLD. For each patient, the Model for End-Stage Liver Disease (MELD) score, total and direct bilirubin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), prothrombin time (PT), and partial thromboplastin time (PTT) were recorded. Signal intensities of the liver, main portal vein, and spleen on pre-contrast, HBP-20, and HBP-30 were documented. Signal intensities were used to calculate liver relative enhancement (LRE), liver-spleen index (LSI), and liver-portal vein index (LPI) for HBP-20 and HBP-30. Improved hepatic enhancement was considered if two or more indices were higher on HBP-30 than HBP-20. A logistic regression model was constructed with improved hepatic enhancement as the outcome. RESULTS: One hundred and twenty-nine patients underwent 142 MRIs. Mean LRE, LSI, and LPI each increased from HBP-20 to HBP-30 (p = 0.004, p < 0.001, and p < 0.001, respectively). Seventy-two point five percent of cases demonstrated improved hepatic enhancement. The odds ratios for improved hepatic enhancement were 0.85 for MELD score (p = 0.02) and 3.2 for the 3 T scanner (p = 0.02), adjusted for age and sex. CONCLUSION: Increasing HBP delay to 30 minutes improves hepatic enhancement in patients with PLD, particularly if using a 3 T scanner. This effect is attenuated with higher MELD scores.

Robust quantization of a molecular motor motion in a stochastic environment.

We explore quantization of the response of a molecular motor to periodic modulation of control parameters. We formulate the pumping-quantization theorem (PQT) that identifies the conditions for robust integer quantized behavior of a periodically driven molecular machine. Implication of PQT on experiments with catenane molecules are discussed.

Pumping restriction theorem for stochastic networks.

We formulate an exact result, which we refer to as the pumping restriction theorem (PRT). It imposes strong restrictions on the currents generated by periodic driving in a generic dissipative system with detailed balance, and provides a universal nonperturbative approach to explore the stochastic pump effect in nonadiabatically driven systems.

Statistics of entropy production in linearized stochastic systems.

We consider a wide class of linear stochastic problems driven off the equilibrium by a multiplicative asymmetric force. The force breaks detailed balance, maintained otherwise, thus producing entropy. The large deviation function of the entropy production in the system is calculated explicitly. The general result is illustrated using an example of a polymer immersed in a gradient flow and subject to thermal fluctuations.

Small bowel faeces sign in patients without small bowel obstruction.

AIM: To evaluate frequency and clinical relevance of the 'small bowel faeces' sign (SBFS) on computed tomography (CT) in patients with and without small bowel obstruction (SBO) presenting with acute abdominal or acute abdominal and flank pain. METHODS: Abdominal CTs of consecutive patients presenting to the emergency department with abdominal or flank pain over a 6 month period were retrospectively reviewed by six radiologists, independently, for the presence of the SBFS. Examinations with positive SBFS were further evaluated in consensus by three radiologists, blinded to the final diagnosis. The small bowel was graded as non-dilated (<2.5 cm) and mildly (2.5-2.9 cm), moderately (3-4 cm) or severely (>4 cm) dilated. The location of SBFS and presence of distal small bowel collapse indicative of SBO was recorded. Imaging findings were subsequently correlated with the final diagnosis via chart review and compared between patients with and without SBO. RESULTS: Of 1642 CT examinations, a positive SBFS was found in 100 (6%) studies. Of 100 patients with a positive SBFS, 32 (32%) had documented SBO. The remaining 68 patients had other non-obstructive diagnoses. SBFS was located in proximal, central, distal and multisegmental bowel loops in one (3.1%), eight (25.0%), 21 (65.6%) and two (6.3%) patients with SBO, and in zero (0%), 10 (14.7%), 53 (77.9%) and five (7.4%) of patients without SBO (p<0.273). The small bowel was non-dilated and mildly, moderately or severely dilated in one (3%), five (16%), 20 (62%) and six (19%) patients with SBO, and in 61(90%), seven (10%), zero (0%) and zero (0%) patients without SBO. Normal or mildly dilated small bowel was seen in all (100%) patients without SBO, but only in six (19%) of 32 patients with SBO (p<0.0001). Moderate or severe small bowel dilatation was seen in 26 (81%) patients with SBO (p<0.0001), but it was absent in patients without SBO. Distal small bowel collapse was found in 27 (84.4%) of 32 patients with SBO, but not in patients without SBO (p<0.0001). A combination of SBFS, moderate or severe small bowel distension and distal collapse was found in 23 (71.9%) patients with SBO (p<0.0001), but was not found in patients without SBO. CONCLUSION: A SBFS is more frequent in patients presenting with acute abdominal/flank pain without bowel obstruction. When seen in association with moderate or severe small bowel dilatation, a SBFS is significantly more common in patients with SBO. When a SBFS is associated with normal or mildly dilated small bowel, the majority of patients have no bowel obstruction.

Diagnosis of weaknesses in modern error correction codes: a physics approach.

One of the main obstacles to the wider use of the modern error-correction codes is that, due to the complex behavior of their decoding algorithms, no systematic method which would allow characterization of the bit-error-rate (BER) is known. This is especially true at the weak noise where many systems operate and where coding performance is difficult to estimate because of the diminishingly small number of errors. We show how the instanton method of physics allows one to solve the problem of BER analysis in the weak noise range by recasting it as a computationally tractable minimization problem.

Dynamical generalization of nonequilibrium work relation.

The evolution of systems in contact with thermal, chaotic, or turbulent surroundings-often modeled with stochastic equations of motion-can be particularly complex when these equations of motion are nonautonomous, that is, when external parameters of the surroundings are varied with time. In this paper we establish a rigorous equality relating the nonautonomous behavior of such a system, to solutions of the corresponding autonomous equations of motion, for arbitrary initial conditions. If the system is initially in thermal equilibrium, we recover previously known results relating nonequilibrium work values to equilibrium probability distributions. We discuss specific examples of our result, and suggest an experimental setting in which it might be verified.

Error correction on a tree: an instanton approach.

We introduce a method that allows analytical or semianalytical estimating of the post-error correction bit error rate (BER) when a forward-error correction is utilized for transmitting information through a noisy channel. The generic method that applies to a variety of error-correction schemes in the regimes where the BER is low is illustrated using the example of a finite-size code approximated by a treelike structure. Exploring the statistical physics formulation of the problem we find that the BER decreases with the signal-to-noise ratio nonuniformly, i.e., crossing over through a sequence of phases. The higher the signal-to-noise ratio the lower the symmetry of the phase dominating BER.

Photophoresis of a fine particle in a selectively excited gas.

Motion in a binary gas mixture of a fine particle affected by resonant optical radiation is considered. The Doppler effect leads to the velocity-selective absorption of the traveling light wave by molecules of one of the gas components. Radiation transfers the absorbing molecules from the ground state to excited ones. As a result, the kinetic cross section and accommodation coefficient of molecules, which have absorbed radiation, change. Maxwellian distribution for the absorbing gas molecules becomes distorted and the aerosol particle begins to be influenced by a force. This photophoretic force and velocity of the photophoresis are calculated by taking both the optical and kinetic characteristics of the gas molecules into account.

Probability of anomalously large bit-error rate in long haul optical transmission.

We consider a linear model of optical transmission through a fiber with birefringent disorder in the presence of amplifier noise. Both disorder and noise are assumed to be weak, i.e., the average bit-error rate (BER) is small. The probability distribution function (PDF) of rare violent events leading to the values of BER much larger than its typical value is estimated. We show that the PDF has a long algebraic-like tail.

Light-induced evaporation and condensation growth of aerosol particles.

The nonisothermal evaporation and condensation of a particle suspended in a vapor-gas mixture under the effect of resonant optical radiation is studied. A traveling light wave is absorbed by the aerosol particle and velocity selectively by vapor molecules. The dependence of the evaporation or condensation rate on optical and thermophysical properties of the particle and gaseous molecules is studied. The free-molecule regime is examined.

Exciton coherence and electron energy loss spectroscopy of conjugated molecules.

Signatures of the exciton coherence size, which controls the nonlinear optical response and luminescence of conjugated systems, in the electronic dynamic structure factor S(q,omega) are calculated. We find that for small molecules the momentum dependence of the lowest exciton resonance is purely geometric, reflecting the molecular size rather than a universal exciton size, as suggested recently. For long chains the q dependence is determined by the interplay of the exciton size and the bond-alternation length scales.

Excitonic funneling in extended dendrimers with nonlinear and random potentials

The mean first passage time (MFPT) for photoexcitations diffusion in a funneling potential of artificial treelike light-harvesting antennas (phenylacetylene dendrimers with generation-dependent segment lengths) is computed. Effects of the nonlinearity of the realistic funneling potential and slow random solvent fluctuations considerably slow down the center-bound diffusion beyond a temperature-dependent optimal size. Diffusion on a disordered Cayley tree with a linear potential is investigated analytically. At low temperatures we predict a phase in which the MFPT is dominated by a few paths.

Excitonic couplings and electronic coherence in bridged naphthalene dimers.

The electronic excitations of naphthalene and a family of bridged naphthalene dimers are calculated and analyzed by using the Collective Electronic Oscillator method combined with the oblique Lanczos algorithm. All experimentally observed trends in absorption profiles and radiative lifetimes are reproduced. Each electronic excitation is linked to the corresponding real-space transition density matrix, which represents the motions of electrons and holes created in the molecule by photon absorption. Two-dimensional plots of these matrices help visualize the degree of exciton localization and explain the dependence of the electronic interaction between chromophores on their separation.