Low temperature method for the production of calcium phosphate fillers

BACKGROUND: Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to develop a low cristalline material similar to bone in porosity and cristallinity. METHODS: Commercial hydroxyapatite (HAp) and monetite (M) powders are mixed with water and compacted to produce cylindrical samples. The material is processed at a temperature of 37–120 degrees C in saturated steam to obtain samples that are osteoconductive. The samples are studied by X-ray powder diffraction (XRD), Vickers hardness test (HV), scanning electron microscopy (SEM), and porosity evaluation. RESULTS: The X-ray diffractions of powders from the samples show patterns typical of HAp and M powders. After thermal treatment, no new crystal phase is formed and no increase of the relative intensity of the peaks is obtained. Vicker hardness data do not show any relationship with treatment temperature. The total porosity decreases by 50–60% according to the specific thermal treatment. Scanning electron microscopy of the surfaces of the samples with either HAp 80%-M 20% (c) or Hap 50%-M 50% (f), show cohesion of the powder grains. CONCLUSIONS: The dissolution-reprecipitation process is more intesive in manufactured samples (c) and (f), according to Vickers hardness data. The process occurs in a steam saturated environment between 37 degrees and 120 degrees C. (c) (f) manufactured samples show pore dimension distributions useful to cellular repopulation in living tissues

Scédosporiose disséminée après transplantation pulmonaire : une complication rare chez le patient atteint de mucoviscidose

Date du colloque&nbsp;: 06/2009</p

Characterization of bone repair in rat femur after treatment with calcium phosphate cement and autogenous bone graft

<p>Abstract</p> <p>Background</p> <p>In this study, the biocompatibility, stability and osteotransductivity of a new cement based on alpha-tricalcium phosphate (alpha-TCP) were investigated in a bone repair model using a rat model.</p> <p>Methods</p> <p>The potential of alpha-TCP on bone repair was compared to autogenous bone grafting, and unfilled cavities were used as negative control. Surgical cavities were prepared and designated as test (T), implanted with alpha-TCP blocks; negative control (C - ), unfilled; and positive control (C + ), implanted with autogenous bone graft. Results were analyzed on postoperative days three, seven, 14, 21 and 60.</p> <p>Results</p> <p>The histological analyses showed the following results. Postoperative day three: presence of inflammatory infiltrate, erythrocytes and proliferating fibroblasts in T, C - and C + samples. Day seven: extensive bone neoformation in groups T and C + , and beginning of alpha-TCP resorption by phagocytic cells. Days 14 and 21: osteoblastic activity in the three types of cavities. Day 60: In all samples, neoformed bone similar to surrounding bone. Moderate interruption on the ostectomized cortical bone.</p> <p>Conclusions</p> <p>Bone neoformation is seen seven days after implantation of alpha-TCP and autogenous bone. Comparison of C - with T and C + samples showed that repair is faster in implanted cavities; on day 60, control groups presented almost complete bone repair. Alpha-TCP cement presents biocompatibility and osteotransductivity, besides stability, but 60 days after surgery the cavities were not closed.</p

Pathology of Antibody-Mediated Rejection: A clinical and pathological perspective

Antibody-mediated rejection (AMR) is now recognized as an important clinical complication of pediatric and adult cardiac transplantation. In addition to causing graft dysfunction, it has been associated with the accelerated development of transplant vasculopathy and graft loss. It can occur early after transplantation, especially in presensitized patients, but late-onset antibody-mediated rejection is now encountered more frequently. It is characterized by microvascular injury centered on the myocardial interstitial capillaries. The diagnosis is currently based on histopathologic and immunophenotypic criteria without reference to clinical status or presence of circulating donor-specific antibodies. The current International Society for Heart and Lung Transplantation grading scheme incorporates the constellation of histopathologic and immunopathologic findings and is now widely utilized for the diagnosis and reporting of AMR

Elevated (> or = 10%) MIB-1 proliferative index correlates with poor outcome in gastric stromal tumor patients: a study of 35 cases

Mitotic activity and tumor size are currently regarded as the most powerful prognostic indicators for patients with gastrointestinal stromal tumor (GIST). This retrospective study evaluated the prognostic accuracy of MIB-1 proliferative index (PI) in combination with these two indicators in 35 GIST patients. Within a high-risk group, determined initially by tumor size and mitotic count, overall survival was significantly shorter for patients whose tumors had PI &gt; or = 10% MIB-1 positive cells. When tumor location (gastric versus small intestine) was taken into account, a combination of tumor size, mitotic count, and PI &gt; or = 10% identified a subgroup of patients with significantly shorter survival for gastric (but not small intestinal) GIST. Based on our results, MIB-1 immunostaining, when used in combination with tumor size and mitotic count, appears to be a powerful tool for identifying patients, especially those with gastric tumors, at high risk of recurrence and early tumor-related deat

Persistent Bacteremia in Rabbit Fetuses despite Maternal Antibiotic Therapy in a Novel Intrauterine-Infection Model

The effect of optimized maternal therapy by bactericidal agents was evaluated in a reproducible rabbit model of Escherichia coli maternofetal infection simulating human pharmacokinetics. Intravenous antibiotic therapy was begun in the pregnant rabbit 12 h after bacterial intrauterine inoculation, using a computer-controlled pump to simulate human pharmacokinetics of ceftriaxone (1 g/day) associated or not with gentamicin (3 mg/kg of body weight/day). Data were compared for fetal survival, quantitative blood cultures, fetal histology in treated versus untreated groups, and maternal and fetal antibiotic concentrations in plasma in treated animals. Antibiotic therapy led to dramatic improvement in maternal outcome (100% survival versus 100% death in the untreated group in association with maternal septicemia). Fetal survival also improved, with the two-drug combination providing a more potent effect. After 3 days of treatment, 32% of fetuses survived with one-drug therapy and 62% with two-drug therapy (Yates corrected χ(2), P < 0.05). In untreated animals, bacterial counts in blood cultures increased rapidly during the first 24 h up to 8.1 ± 0.5 log CFU/ml, but remained relatively constant at all times with antibiotic treatment: 4.5 ± 0.7 log CFU/ml at the start of treatment and 6.2 ± 0.4 and 5.2 ± 0.9 log CFU/ml after 72 h for one- and two-drug therapy, respectively (data are means ± standard deviations). The failure of animals to be cured after 3 days of treatment was not due to an inadequate concentration of ceftriaxone, as the residual level in fetal serum at sacrifice was more than 1,000 times the MIC of the microbe. Unexpectedly, inflammation in fetal lung decreased in the treated group after as little as 24 h of antibiotic therapy, despite persistent bacteremia. Although maternal outcome improved and drug concentrations were above the MIC, the treatment did not achieve sterilization of fetuses in utero for this rabbit E. coli maternofetal infection. However, fetal survival showed some improvement, and the histologic features of lung inflammation were reduced