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[en] Here, we investigate how competition in the Eden model is affected by short range dispersal and the requirement that site updates occur only after several updates of the same site have been attempted previously. The latter models the effect of tissue or media resistance to invasion. We found that the existence of tissue intensifies Natural Selection and de-accelerating Genetic Drift, both to a limited extent. More interestingly, our results show that short-range migration can eliminate genetic demixing and conceal natural selection. (paper: biological modelling and information)
[en] Highlights: • Primary subcutaneous cystic echinococcosis is extremely rare. • Typical features of hydatid cyst may not be demonstrated in some cases. • Epidemiological data is very important to make a suspicion in endemic countries.
[en] Chondromyxoid fibroma is a rare benign cartilaginous neoplasm that mostly affects the metaphyseal region of the long bones. The tibia, small tubular bones of the foot, the distal femur and pelvis are common locations, but involvement of the vertebral bones, especially the cervical vertebra, is very rare. Radiographic features show typical characteristics and this tumor often presents as a lobulated, eccentric radiolucent lesion with no periosteal reaction. In addition, geographic bone destruction is seen in all cases. We present an adult female with a one-year history of neck pain, and ultrasound findings that suggest a right paravertebral muscular lesion due to inflammatory or neoplastic origins. The histopathological studies confirmed that the biopsied specimen was a chondromyxoid fibroma of the cervical vertebrae laminae and spinous processes (C3 and C4) with abutting soft tissue. Despite the unusual location and soft tissue presentation, a chondromyxoid fibroma should be considered in the differential diagnosis of a cervical bone lesion
[en] We present herein 3D elastic tensor imaging (3D ETI), an ultrasound-based volumetric imaging technique to provide quantitative volumetric mapping of tissue elastic properties in weakly elastic anistropic media. The technique relies on (1) 4D ultrafast shear wave elastography (SWE) at very high volume rate (e.g. > 8000 Hz, depending only on the imaging depth), (2) a volumetric estimation of shear wave velocity using the eikonal equation and (3) a generalized 3D elastic tensor-based approach. 3D ETI was first evaluated using numerical simulations in homogeneous isotropic and transverse isotropic media. Results showed that 3D ETI can accurately assess tissue stiffness and tissue anisotropy in weakly transversely isotropic media (elastic fractional anisotropy coefficient < 0.34). Experimental feasibility was shown in vitro in a transverse isotropic phantom. Quantification of the elastic properties by 3D ETI was in good agreement with 2D SWE results performed at different orientations using a clinical ultrafast ultrasound scanner. 3D ETI has the potential to provide a volumetric quantitative map of tissue elastic properties in weakly transversely isotropic soft tissues within less than 20 ms of acquisition for the entire imaged volume. (paper)
[en] The image of quality of 106 consecutive focal hepatic lesions (44 cysts, 40 solid lesions, and 22 intrahepatic duct stones or calcifications) and various targets (gray-scale targets, anechoic targets, and monofilament targets) in tissue mimicking phantom were examined with conventional US (CI) and 3 different modes of THI technique THI-1, THI-2, and THI-3 with transmitted frequencies of 2.5 MHz, 2.8 MHz, 3.0 MHz, respectively. Focal hepatic lesions and targets were divided into 2 or 3 groups according to the depth of lesion. Each set of images was evaluated by two radiologist. In clinical study (the margin and contrast of the lesions, internal echo and posterior sonic enhancement of cysts and posterior shadowing of calcification/stone). In phantom study (margin and contrast of targets). The contrast of all targets in phantom except monofilament target were measured using Image Pro-Plus (Media Cybemetics). Tissue harmonic US provides better image quality compared to conventional US. Variable transmitted frequency can be selected used in THI according to the depth of each hepatic lesion.
[en] Modern orthodontics implies not only occlusal excellence, but also the positioning of teeth to produce optimal facial harmony for the individual patients. Several methods have been used in the study of facial height, width and depth were made from living subjects. These methods, however, complicate to control the subjects, therefore many investigators have used profile cephalometric technics. Practically, cephalometric technics were used in orthodontic treatment, maxillo-facial surgery and anthropometric studies. Author was studied to investigate the normal standards of soft tissue profile in Korean adolescences. The subjects consisted of 53 males and 54 females from 17 to 22 years of age and with normal occlusion and acceptable profile. Aluminum filter was designed to obtain both hard and soft tissue structures on a single film. Eight profile landmarks were plotted and drawn on the tracings of all cephalograms and eighteen depth, height an d angles were measured from each landmarks of the cephalograms. The following conclusions were obtained from this studies; 1. Total facial convexity was 170.75 in males and females samples and lower facial and labiomandibular convexity were each of 141.44, 171.05. 2. Maxillary and mandibular sulcus angulations were 137.61, 129.52 and upper and lower lip inclinations were each of 12 3.26 and 49.56 in male and females. 3. Soft tissue depth of several points were as follows; Subnasale 18.74 mm in males and 16.65 mm in females Pogonion 13.40 mm in males and 13.07 mm in females upper lip 14.06 mm in males and 11.91 mm in females lower lip 15.46 mm, 13.63 in males and females 4. The protrusion of nose were 16.28 mm in males and 15.56 mm in females 5. The vertical length of upper and lower lips were 25.67 mm, 52.96 mm and the lip posture was indicated 93.43 per cent (closed state) in centric occlusions.
[en] Further understanding of bone healing mechanisms, bone physiology and bone biology, transplantation immunology, and development of Tissue Banking procedures has enabled oral and maxillofacial surgeons to reconstruct even the most difficult bony defects successfully with the preserved allogeneic bone implant. Although it had been known that bone allografts were clinically effective, its application has not been widespread until the reports of Inclan (I 942), Hyatt and Butler (I 950), and Wilson (I 95 1). Tissue Banking provides the surgeon with a readily available, relatively inexpensive, and relatively safe selection of allogeneic bone for clinical use. Now autogenous bone and allogeneic bone implants present a wide variety of surgical options to surgeons, whether used separately or in combination. The surgeons are able to make judicious and fruitful choices, only with a thorough knowledge of the above-mentioned biological principles and skillful techniques. Many kinds of bone grafting techniques have been tried for reconstructing defective osseous tissues of the oral and maxillofacial region, though they have varying degrees of success. The osseous defects which require grafting include those of various size, shape, position, or amount. Unlike autogenous grafts, whose function is to provide osteogenic cells, allografts are purely passive, offering only a matrix for the inductive phase of bone healing. The condition of the recipient bed is of primary importance, because the host must produce all of the essential elements for the bone allograft to become incorporated. Depending on the processing methods of the allogeneic bone, the bone graft materials have different qualities, different healing potentials and different indications. Proper selection of grafts and surgical techniques requires an understanding of graft immunology and the mechanisms of graft healing. The surgeons should know about the biological principles to raise the clinical success rate. Combinations of allografts and autografts for mandibular reconstruction have enjoyed great success since their introduction in the late 1960's and early 1970's. Due to its high osteogenic potential, marrow and cancellous bone was used for reconstruction of the mandible. For reconstruction of large defects, surgeons used a scaffold to support the cancellous bone. This practice led to the use of allogeneic bone crib in which the cancellous bone could be packed. Reconstruction of the mandible by this combination is now very commonplace
[en] Radiation-sterilization of connective tissue allografts (bone including) with a dose of 35 kGy is routinely used in the Central Tissue Bank in Warsaw since 1963. This method of sterilization offers many advantages: good penetration ability, relatively low temperature rise, and possibility of sterilization of grafts in closed beforehand vials, which protects against secondary contamination. It should be kept in mind, however that high doses of ionizing radiation (in the range of 20-35 kGy) used for sterilization evoke many chemical and physical changes which may influence biological properties of grafts. These changes have been studied using various methodological approaches. Using electron paramagnetic resonance (EPR) spectrometry it has been found that in radiation-sterilized bone two types of paramagnetic entities are generated: i/ coliagen radicals which are unstable and disappear completely in the presence of air oxygen, ii/ very stable at room temperature paramagnetic defects (centers) localized in the crystalline lattice of bone mineral. These stable paramagnetic defects have been treated as a new kind of markers and used for: a/ quantitative evaluation of remodeling process of radiation-sterilized bone allografts preserved by lyophilization or deep freezing; b/ estimation of the dose of ionizing radiation absorbed by living organism in the case of accidental exposure (skeleton serving as a dosimeter) and for control of radiation-sterilization process. The effect of radiation-sterilization and preservation procedures on bone allografts was studied using a model of heterotopically induced osteogenesis and measuring the solubility of bone collagen in vitro. It has been observed that lyophilized bone allografts irradiated at room temp. with doses of 35 and 50 kGy, respectively, were very quickly resorbed in vivo and did not induce osteogenesis, while lyophilized as well as deep-frozen matrices irradiated at -7OoC were slowly resorbed and induced de novo bone fon-nation, even after irradiation with a dose of 50 kGy. In lyophilized samples irradiated at room temp. a striking increase of collagen solubility was noted: 12-fold and 27-fold after the dose of 35 and 5OkGy, respectively, while in frozen samples the solubility of collagen was only 3-times higher than in non-irradiated controls. It has been found that radiation-induced damage of bone grafts depends mainly on two groups of factors: a/conditions of irradiation (dose, temperature), b/ physical state of bone samples: particularly the presence or absence of water. Radiation-induced damage of frozen samples may be as much as 4-times lover, if related to the damage rate at room temp. The presence of water in irradiated specimens might also strongly influence the nature of chemical reactions involved and may diminish the radiation damage
[en] Subglottic-tracheal stenosis is a common clinical entity. Handling on severe case is often problematic. Various tracheal replacement techniques have been used with varying degree of success and dispute. In this study we worked on cryopreserved irradiated tracheal homograft, of which its use in human has not been reported. The tracheas were harvested from donor cadavers within 24 hours of death in a sterile condition. After 1-2 weeks of preservation at -70 degree C, the grafts were irradiated at 25 kGy, then stored at -70 degree C until used. Four patients, 2 males and 2 females (aged 2-40 years, mean 16 years) with severe subglottic-tracheal stenosis underwent segmental tracheal graft reconstruction using this graft. Immunosuppressant was not given in any patient. The follow up period ranged from 11-1 5 months. Three patients were successfully decapulated, 1 patient developed local infection and dislodgement of intraluminal stent with subsequent restenosis. Postoperative tracheal lumen appeared near normal with histologic evidence of normal respiratory epithelium at the grafted site. In conclusion, cryopreserved irradiated tracheal homograft is a valuable alternative for tracheal transplant or reconstruction, without the need of immunosuppression