The effect of decreasing the grain size on the biocompatibility, cell-material interface, and mechanical properties of microwave-sintered monophase hydroxyapatite bioceramics was investigated in this study. A nanosized stoichiometric hydroxyapatite powder was isostatically pressed at high pressure and sintered in a microwave furnace in order to obtain fine grained dense bioceramics. The samples sintered at 1200°C, with a density near the theoretical one, were composed of micron-sized grains, while the grain size decreased to 130 nm on decreasing the sintering temperature to 900°C. This decrease in the grain size certainly led to increases in the fracture toughness by much as 54%. An in vitro investigation of biocompatibility with L929 and human MRC-5 fibroblast cells showed noncytotoxic effects for both types of bioceramics, while the relative cell proliferation rate, cell attachment and metabolic activity of the fibroblasts were improved with decreasing of grain size. An initial in vivo investigation of biocompatibility by the primary cutaneous irritation test showed that both materials exhibited no irritation properties.
The purpose of this study was to evaluate the tissue response induced by bioceramical materials (BCM) implanted in rat subcutaneous tissue. Thirty two rats were assigned to 6 groups, as following: control group i.e. not treated; dental ceramic (DC) implants; alfa tricalcium phosphate synthetised at 22 MPa (αTCP22) and at 45 MPa (αTCP45); hydroxyapatite synthetised at 22 MPa (HAP22) and at 45 MPa (HAP45). Contra lateral sides of all test animals represented the blank control surgically incisied at the paravertebral sockets. The experimental groups received subcutaneous implants of the test BCM materials. Samples were collected after 14 days and processed histologically. Inflammatory reactions were noted microscopically. The inflammatory infiltrate consisted of lymphocytes, polimorphonuclears, macrophages and mastocytes. At same time there were signs of increased fibrosis around the graft places. In conclusion, the implant sides compared with surgical incision wounds induced a foreign body-type granuloma with subsequent fibrosis around the grafts. The presence of a capsule at the interface with BCM in rat subcutis did not elicit any remarkable immune responses, thus being considered biocompatible. By evaluating different responses according to BCM, the most intense tissue reaction was noticed at HAP45, graded as severe, and mild to moderate for DC, HAP22 and alfa tricaltium phosphate
Inclination angle may be regarded as the vital predisposing factor since it differs considerably in unruptured and ruptured aneurysms. Aneurysms with blood stream angle smaller than 115 degrees have very small probability of rupture, while blood stream angle bigger than 150 degrees presents a high risk of rupture.
AIM: Intracranial aneurysm rupture is followed by high mortality and morbidity. In order to understand the aneurysm's natural course, it is necessary to recognize the predisposing factors for the rupture. ResULTs:The ratio between the width of the aneurysm neck and diameter of the carrying blood vessel -artery in ruptured aneurysms (OR) was 1.58±0.61, and in unruptured aneurysms 1.14±0.52 (p<0.01). Aspect ratio of ruptured aneurysm was 1.89 ± 0.59, and in unruptured 1:33 ± 0.17. The angle of inclination of ruptured aneurysms was 139.22 ± 21.53, while in unruptured aneurysms it was 101.73 ± 21.26. CoNCLUsIoN:Based on the results of our research, a predictive model of morphometric characteristics of the vessel bearing the aneurysm to rupture can be identified: an irregular shape of the aneurysm, AR> 1.6, OR> 1.5 and inclination angle >135 deg. soNUÇ: Araştırmamızın sonuçları temelinde rüptüre olacak anevrizmayı taşıyan damarın morfometrik özelliklerinin prediktif bir modeli tanımlanabilir: Anevrizmada düzensiz şekil, aspekt oranı >1,6, OR >1,5 ve inklinasyon açısı >135 derece.
Neurointensive care of patients with subarachnoid haemorrhage is based on the theory that clinical outcome is the consequence of the primary haemorrhage and a number of secondary insults in the acute post haemorrhage period. Several neuromonitoring techniques have been introduced or accomplished into clinical practice in the last decade with the purpose of monitoring different but related aspects of brain physiology, such as cerebral blood flow (CBF), pressure within the cranial cavity, metabolism, and oxygenation. The aim of these techniques is to obtain information that can improve knowledge on brain pathophysiology, and especially to detect secondary insults which may cause permanent neurological damage if undetected and untreated in "real time", at the time when they can still be managed. These techniques include intracranial pressure (ICP) measurements, jugular venous oxygen saturation, near-infrared spectroscopy, brain tissue monitoring, and transcranial Doppler. The available devices are limited because they measure a part of complex process indirectly. Expense, technical difficulties, invasiveness, limited spatial or temporal resolution and the lack of sensitivity add to the limitation of any individual monitor. These problems have been partially addressed by the combination of several monitors known as multimodality monitoring. In this review, we describe the most common neuromonitoring methods in patients with subarachnoidal hemorrhage that can assess nervous system function, cerebral haemodynamics and cerebral oxygenation.
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