Access-Site Complications in Mechanical Thrombectomy for Acute Ischemic Stroke: A Review of Prospective Trials.

BACKGROUND: A shift has occurred in interventional cardiology from transfemoral to transradial access due to a 70%-80% decrease in complications. This shift has not yet taken place in other interventional specialties, perhaps owing to the lack of generalizability of findings in the cardiology data. PURPOSE: Our aim was to assess data from the recent mechanical thrombectomy prospective trials to better understand the access-site complication rate. DATA SOURCES: Articles were systematically sourced from the National Center for Biotechnology Information PubMed archive. STUDY SELECTION: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, prospective, randomized controlled trials published after 2008 with mention of major and/or minor femoral access-site complications in neuroendovascular mechanical thrombectomies were included. DATA ANALYSIS: Major and minor femoral access-site complications were extracted. A total complication rate was calculated with major access-site complications alone and combined with minor access-site complications. DATA SYNTHESIS: Seven prospective studies of 339 total screened met the inclusion criteria. Eleven major access-site complications were identified in of 660 total interventions, revealing a major access-site complication rate of 1.67% for patients undergoing mechanical thrombectomy with transfemoral access. If minor access-site complications were included, 35 total incidents were detected in 763 interventions, resulting in a total complication rate of 4.59%. LIMITATIONS: Multiple unspecified vessel and procedure-related complications were mentioned in the studies. CONCLUSIONS: The overall rate of major access-site complications was 1.67% in this review, which is not low and poses a risk to patients. We suggest further investigation into the feasibility and complication rates of alternative access sites for neurointerventional procedures.

Continuum modeling of mechano-dependent reactions in tissues composed of mechanically active cells.

Mechanical forces and interactions participate in ontogenesis at all scale levels: intracellular, cellular, and supra-cellular, the latter including tissue level. This concept, now almost trivial, was finding its way with difficulties, and the works of L.V. Beloussov have played a decisive role in its establishment. The continuum approach presented in this study makes it possible to take at the tissue level into account both relative motion of cells and forces that control this motion. The characteristics which allow us to take into account general active properties of the cell medium are described, possible mechanisms represented by these characteristics are discussed, and a concise review of our results obtained to date is presented. In the strain rate tensor, two separate components are distinguished, one of them being related to deformation of individual cells and the other to cell rearrangement. A separate phase (submedium) that corresponds to active subcellular elements associated with rearrangement-controlling active stresses is also introduced. Within this general approach two specific models are considered. The first made it possible to establish general mechanisms whose account enabled us to satisfactorily describe the experimental results of L.V. Beloussov and collaborators, concerning mechano-dependent reactions of embryonic epithelium explants. On the assumptions that the active stress responds to cell shape deviations and the rearrangement strain rate component depends on the active stresses developed by pseudopodia, the cell shape and tissue stress evolution observed experimentally in stretched explants, as well as their post-release deformation, are reproduced. The second particular model considers self-organization in a conglomerate of loosely connected cells in the presence of a fluid phase. In this case, the active stress was assumed to nonlocally depend on the density of cells and the rearrangement strain rate on the active and passive stresses. Due to loss of stability of the spatially homogeneous state, various structures similar to those observed in embryogenesis develop. In particular, within the conglomerate, a cavity can be formed, a certain level of the fluid pressure being necessary for this.

[Mathematical Modeling of the Stretching-induced Elongation of an Embryonic Epithelium Layer in the Absence of External Load].

A clue to understanding the deformation of a plane embryonic epithelium layer unloaded after a short time uniaxial stretch and fixation in a stretched state over different time periods is found. The first steps in the understanding of this process come from the knowledge about the uniform stretching of the tissue fragment (explantate) with the subsequent stretching at a fixed length. In this study we used the earlier developed continuum model that describes the stress-strain state of the epithelial tissue taking into account the parameters that characterize the shape of the cells and their stress state, and also the active stresses they exert when interact with one another. The experimentally observed continuation of deformation of the stretched tissue after the cessation of action of the external force is described theoretically as a result of active cell reactions to the mechanical stress. The strong effect of the duration of explantate fixation on its further elongation and the cell activity pattern is demonstrated.

A simple model for estimating the active reactions of embryonic tissues to a deforming mechanical force.

Active reactions of embryonic tissues to mechanical forces play an important role in morphogenesis. To study these reactions, experimental models that enable to evaluate the applied forces and the deformations of the tissues are required. A model based upon the active intrusion of a living early gastrula Xenopus embryo into a tube half the embryo in diameter is described. The intrusion is initially triggered by a suction force of several dozen Pa but then continues in the absence of external driving force, stopping immediately after the entire embryo has penetrated into the tube. The process can be stopped by cytoskeletal drugs or by the damage of the part of the embryo still non-aspirated and is associated with the transversal contraction and meridional elongation of the non-aspirated part of the embryo surface and quasi-periodic longitudinal contractions/extensions of the cells within the part already aspirated. We suggest that this reaction is an active response to the embryo deformation and discuss its morphogenetic role. The problem of estimating the elastic modules of embryonic tissues is also discussed.

Breast cancer: importance of spiculation in computer-aided detection.

PURPOSE: To determine the prevalence of spiculation in a large series of screening-detected breast cancers appearing as masses on mammograms and to assess the sensitivity of a computer-aided detection (CAD) algorithm that uses spiculation measures in the detection of such lesions. MATERIALS AND METHODS: Six hundred seventy-seven consecutive cases of breast cancers detected as masses on mammograms were independently reviewed by three radiologists who determined if the lesions were spiculated. All cancers were then analyzed by the CAD system. RESULTS: All three radiologists interpreted 375 (55%) of the 677 masses as being spiculated on at least one view. The CAD algorithm correctly marked 322 (86%) of the 375 clearly spiculated masses, with a mean of 0.24 additional mass mark per image. With a looser definition of spiculation, 585 (86%) of the 677 masses were called spiculated by at least one radiologist on one view. The algorithm correctly marked 464 (79%) of the 585 lesions that were spiculated or possibly spiculated. CONCLUSION: Spiculation was clearly present in a majority (55%) of consecutive screening-detected breast cancer masses found on mammograms in a large clinical trial. Incorporation of spiculation measures is, therefore, an important strategy in the detection of breast cancer with CAD. A present-generation CAD algorithm correctly identified a large proportion (86%) of spiculated breast cancers.

Tension-dependent collective cell movements in the early gastrula ectoderm of Xenopus laevis embryos.

Ventral ectodermal explants taken from early gastrula embryos of Xenopus laevis were artificially stretched either by two opposite concentrated forces or by a distributed force applied to the internal explant's layer. These modes of stretching reflect different mechanical situations taking place in the normal development. Two main types of kinematic response to the applied tensions were detected. First, by 15 min after the onset of concentrated stretching a substantial proportion of the explant's cells exhibited a concerted movement towards the closest point of the applied stretching force. We define this movement as tensotaxis. Later, under both concentrated and distributed stretching, most of the cell's trajectories became reoriented perpendicular to the stretching force, and the cells started to intercalate between each other, both horizontally and vertically. This was accompanied by extensive elongation of the outer ectodermal cells and reconstruction of cell-cell contacts. The intercalation movements led first to a considerable reduction in the stretch-induced tensions and then to the formation of peculiar bipolar "embryoid" shapes. The type and intensity of the morphomechanical responses did not depend upon the orientation of a stretching force in relation to the embryonic axes. We discuss the interactions of the passive and active components in tension-dependent cell movements and their relations to normal morphogenetic events.

Chronic inhalation exposure of rats to nitromethane.

Male and female Long-Evans rats were housed in inhalation chambers and exposed to vapors of nitromethane (NM) at either 100 or 200 ppm. The animals were exposed 7 hr per day, 5 days per week for 2 years. Control groups of rats were also housed in a similar inhalation chamber, but NM was not introduced into the chamber. The animals were observed daily for signs of pharmacologic or toxicologic effect and body weights were recorded periodically. At the 2-year termination of the exposure period, clinical laboratory examinations (serum chemistry and hematology) were performed on selected animals and all surviving animals were sacrificed. All animals were necropsied and subjected to a thorough histopathologic examination. During the study there were no pharmacologic effects from exposure to NM at either 100 or 200 ppm. There was no effect on mortality on either sex at either exposure level. Body weights of male rats exposed to NM were not significantly different from those of control rats, but the body weights of female rats of both exposure groups were slightly less than their controls. There was no effect of exposure of rats of either sex to either level of NM on hematology. There were no clinically significant effects on serum chemistry. There were no effects of exposure to NM on organ weights. There were no significant differences in the nonneoplastic or neoplastic pathology related to exposure to NM.

[The interaction of a root growing vertically with a rigid barrier]. / Vzaimodeistvie vertikal'no rastushchego kornia s zhestkim prepiatstviem.

Bending root tip that grows outside the soil is investigated. The decrease of growth rate due to increasing compressive stress leads to the destabilization of uniform solution, whereas differential growth that is controlled by root cap gravitropism is a stabilizing factor. The interplay of both processes leads to diverse behaviour types.

Chronic inhalation exposure of rats to vapors of nitroethane.

Male and female Long-Evans rats were exposed in inhalation chambers to vapors of nitroethane at concentrations of 100 or 200 ppm, 7 hr per day, 5 days per week for 2 years. During the study, general observations were made daily and body weights were obtained weekly for the first 6 months of the study and biweekly thereafter. Any rats that were found dead or sacrificed moribund during the 2-year exposure phase of the study were given a thorough gross examination and tissues were retained for microscopic examination. After 2 years of inhalation of nitroethane, all surviving rats were sacrificed and subjected to the same thorough gross examination. Blood samples were obtained from representative groups of animals for hematology and serum chemistry studies. All rats were examined histopathologically. Exposure of the rats to nitroethane had no pharmacologic effects nor were there any effects on mortality of rats of either sex at either level of exposure. Throughout most of the investigation, body weights of both sexes of both exposed groups were slightly less than those of respective controls, but lack of a well-defined dose-response relationship suggested the involvement of factors other than just exposure to nitroethane. There were no effects of exposure to nitroethane on hematology nor were there any biologically significant effects of exposure to nitroethane on clinical chemistry or on organ weights. No significant nonneoplastic or neoplastic pathology was found as a consequence of exposure of the rats to nitroethane.

Pasteurella multocida septicemia. Experience at a cancer hospital.

Pasteurella multocida most commonly infects patients with animal contacts. Life-threatening systemic disease is distinctly uncommon in otherwise healthy persons and usually occurs in patients with chronic predisposing disease. Two cases of sepsis occurred in a cancer hospital, and we surmise that specific predisposing factors existed in our patients as in prior reported cases of sepsis in patients without cancer. These factors include animal contact, open wounds, and, most important, advanced hepatic disease.

The centrineurogenic etiology of the respiratory distress syndrome: induction by isolated cerebral hypoxemia and prevention by unilateral pulmonary denervation.

Twenty-eight anemic control dogs were subjected to isolated cerebral hypoxemic (PO2,35+/-5 mm Hg) perfusion for 2 hours. All were found to have functional pulmonary impairment. Two hours later, twenty were sacrificed and found to have the bilateral anatomic complex of the respiratory distress syndrome (RDS). All those not sacrificed expired within 20 hours with progressive respiratory distress and at autopsy had the bilateral anatomic complex. Twenty-three beagles with chronic denervation (autotransplantation) of the left lung also were subjected to the 2 hour isolated cerebral arterial hypoxemic perfusion. Minimal pulmonary functional impairment was measurable in all. Ten of sixteen were long-term survivors. The six that succumbed did not appear to suffer respiratory deaths. These six, as well as seven sacrificed 2 hours after perfusion, had the anatomic complex of RDS in the normally innervated right lungs. However, the denervated left lungs were anatomically normal. These findings are offered as additional evidence that RDS has a centrineurogenic etiology. We postulate the following sequence: "shock" causes cerebral (probably hypothalamic) cellular oxygen deprivation and dysfunction; there is autonomically mediated, increased resistance of the pulmonary venules ("postcapillary sphincters"); this leads to capillary hypertension, congestion, hemorrhage, edema, surfactant inactivation, and atelectasis. Pulmonary denervation blocks this sequence and protects the lung.

The centrineurogenic etiology of the respiratory distress syndrome: protection by unilateral chronic pulmonary denervation in hemorrhagic shock.

Anemic beagles were subjected to 40 mm Hg hemorrhagic shock for 2 hours, which uniformly induced the pulmonary lesions of the "respiratory distress syndrome" (RDS) bilaterally in all six controls. For six subjects with complete denervation of the left lung 2 months previously, the shock regimen induced the lesions in the normally innervated right lungs; all reimplanted, denervated left lungs remained anatomically intact. This is presented as additional evidence for a centrineurogenic etiology for RDS.

The centineurogenic etiology of the respiratory distress syndrome. Protection afforded by anemia and pulmonary denervation against lung lesions of oxygen toxicity.

For beagles respiring 100 per cent oxygen at ambient pressure, anemia protected against the development of the lung lesions of oxygen toxicity. Similarly, unilateral pulmonary denervation was protective of the affected lung but not of the normally innervated, contralateral lung. This indicates that the lung lesions are triggered by the toxic effect of elevated PO2 at a remote site, most likely the sensitive central nervous system.