[Erythrocyte removal from bone marrow by density gradient separation using the COBE 2991 cell processor with the triple-bag processing set]. / Désérythrocytation de moelle osseuse par gradient de densité sur COBE 2991 avec le kit triple "bérets".

ABO-incompatible bone marrow transplantation requires red blood cell depletion. Lots of laboratory adopted the technique of density gradient centrifugation (Ficoll-hypaque) using the COBE 2991 cell processor with simple-bag processing set. However, tubing of this set is not adapted to the currently available peristaltic pumps. Moreover, two other sets are required: one for the buffy-coat and one for postgradient cell washing. We developed a method using triple-bag processing set to conduct whole-step procedure (concentration, Ficoll and washing). Peristaltic PVC tubing is provided in one line of the set allowing a safe processing without several connections thus reducing risks of microbial contamination. First, we used buffy-coat of total blood for training, then, we carried out red cell depletion of healthy bone marrow donors. The red blood cell depletion was 97.9+/-1.1% and CD34+ recovery was 89.6+/-8.7%. These results are very close to those obtained with the simple-bag set (red cell depletion.=94.0+/-6.8% and CD34+ recovery=95.9+/-20.3%). We conclude that the triple-bag system, very little used in France, is practical, simplified the manipulation and is more safety than the simple-bag set.

A synthetic aragonite-based bioceramic: influence of process parameters on porosity and compressive strength.

We investigate the influence of process parameters such as weight fraction and particle size of pore-former, and isostatic pressure, on porosity and compressive strength of non-sintered porous calcium carbonate biomaterials compacted at high pressure in uniaxial or isostatic mode. Experiment design and results analysis are performed according to a two-level 2k factorial design method (FDM). Results indicate that only the weight fraction of pore-former (wt fpf) influences significantly the porosity and the compressive strength. The porosity P, is described by a linear function of wt fpf, and the compressive strength sigma(comp), by an exponential one. For materials compacted under uniaxial pressing: P (vol%) = 33.7 + 85.4 (wt fpf) and sigma(comp) (MPa) = 28.8e(-9.2(wt fpf)) with 0.1 < or = wt fpf < or = 0.3. For materials compacted in isostatic mode: P (vol%) = 33.9 + 82.1 (wt fpf) and sigma(comp) (MPa) = 24.0e(-7.0(wt fpf)) with 0.15 < or = wt fpf < or = 0.35. The pore-former particle size has no significant influence on both properties. The increase in isostatic pressure provides slightly lower porosity and better compressive strength. For a fixed fraction of pore-former, isostatic pressing leads to a better compressive strength than uniaxial pressing. This study indicates that, for a constant amount of pore former, the size of macropores can be adjusted to reach optimal bone-ingrowth without change in compressive strength.

A self-setting single-component calcium phosphate cement.

Following an original synthesis route, we have prepared a single-component calcium phosphate apatite-like powder which settles and hardens when mixed with deionized water in an approximative 1.2 g:1 ml ratio. This paper describes the first physico-chemical studies and characterizations of the material. Observations of its in vitro behavior show a slight volume contraction and toxicity against fibroblasts bone marrow cells on disks of compacted powder. It is suggested that after an improvement of the powder characters such as grain size, and the choice of another hardening liquid, to name a few, this material should be a potential--or an ingredient of--bone cement.

[Primary malignant melanomas of the urethra. Apropos of 4 cases]. / Les mélanomes malins primitifs de l'urëthre. A propos de 4 cas.

The authors report four cases of primary malignant melanoma of the urethra. The rarity of these lesions can lead to their mis-diagnosis. Only histological examination of a biopsy specimen stained with Fontana stain can confirm the diagnosis. These tumours have a very poor prognosis because of their tendency to locally invade the corpus cavernosus in men and the vulva and vagina in women. These lesions carry a high risk of lymph node and metastatic dissemination. For very limited tumours, the authors recommend a relatively extensive urethrectomy (2/3 of the urethra in women and amputation of the penis in men with a perineal urethrostomy) completed by interstitial irradiation with irridium 192 (6,000 rads) and inguinal lymphadenectomy. In larger tumours, with lymph node invasion, the very brief survival time makes extensive excision inappropriate. Limited palliative surgery is to be preferred. Radiotherapy and chemotherapy have no proven effectiveness.