Detection of P-glycoprotein with a rapid flow cytometric functional assay using Fluo-3: evaluation of sensitivity, specificity and feasibility in multiparametric analysis.

The specificity and sensitivity of a flow cytometric assay simultaneously measuring expression and transport function of the multidrug resistance associated P-glycoprotein (Pgp) was evaluated. The monoclonal antibody (mAb), MRK16 was used to detect phenotypic Pgp expression while Fluo-3-AM was used as a fluorescent substrate in a Pgp functional transport assay. The specificity of the functional assay was examined in two vinblastine selected human leukemic cell lines (K562/VLB2.5 and CCRF-CEM/VLB50) with acquired Pgp overexpression. Downmodulation of Pgp function in these cell lines could be demonstrated with different substances (verapamil, vinblastine, trifluoperazine, cyclosporin A, progesterone and quinidine) and was proven to be consistently higher in the vinblastine selected cells than in their non-selected drug sensitive counterparts. Unexpectedly, modulator activity was also observed in drug sensitive K562 and CCRF-CEM cell lines despite the inability to detect Pgp in those cells by MRK16 flow cytometrically. Low level expression of the MDR1 gene encoding Pgp in sensitive K562 cells was however demonstrated with a sensitive RT-PCR procedure. The small effect of Pgp modulators in non-drug selected cells could therefore be attributed to low level basal expression of Pgp and illustrates the sensitivity of the functional assay. Also, the effect of various Pgp modulators on Pgp function was more pronounced in a subpopulation of Pgp expressing lymphocytes than in lymphocytes which did not express Pgp. Finally, a correlation was found between discrete variations in Pgp expression and Pgp function of CD4+ lymphocytes, underscoring the feasibility of the functional assay in a triple parametric procedure. The triple parametric assay holds promise to detect Pgp expression and function in clinical samples containing mixtures of malignant and non-malignant cells.

Differential gene expression of the neural cell adhesion molecule (N-CAM) in a panel of multiple myeloma cell lines.

A striking feature of myeloma plasma cells concerns their expression of the neural cell adhesion molecule (N-CAM). The regulation of this particular expression is, however, not known. In this study, the N-CAM (CD56) gene regulation was examined in a panel of multiple myeloma (MM) cell lines. In this panel, both N-CAM-positive and -negative cells were analysed, reflecting the in vivo situation where a minority of MM patients have CD56-negative plasma cells at diagnosis or where in cases of extramedullary involvement CD56 expression decreases. At least two N-CAM mRNAs were found in the cell lines expressing the 140 kDa isoform. With one exception, no N-CAM transcripts could be detected in the N-CAM-negative cell lines. No structural differences could be found in the genomic organization of the N-CAM gene, or in the regulatory promoter region when CD56-positive and -negative cell lines were compared. In transfection studies, however, transcriptional activity of the N-CAM promoter was observed in N-CAM-negative cells, leading us to conclude that the up-regulation of N-CAM in MM cannot be explained by a simple transcriptional gene activation.

Establishment and characterization of a human stroma-dependent myeloma cell line (MM5.1) and its stroma-independent variant (MM5.2).

Although IL-6 has been identified as a major growth factor in multiple myeloma (MM), it is believed that maintenance of tumor growth in vivo depends on one or more additional stroma-derived factors. We describe a new human myeloma cell line (MM5.1) that can be maintained in the presence of bone marrow-derived stromal cell layers, and not only when cultured with exogeneous IL-6. This cell line expresses the same immunoglobulin kappa light chain RNA sequence as the patient's original tumor cells, has a plasma cell morphology and expresses plasma cell antigens (cytoplasmic kappa light chain, CD38, BB4). Without the presence of stromal factors, MM5.1 cells become apoptotic. A low proliferative effect was observed in the presence of oncostatin M (OSM) but other cytokines (IL-10, IL-11, stem cell factor (SCF) and leukemia inhibitory factor (LIF)) had no effect at all. We observed that MM5.1 cells also grow when physically separated from stromal cell layers by a 0.45 microm microporous membrane or when cultured in conditioned medium from stromal marrow cells. Unexpectedly, the growth in stromal supernatants was markedly inhibited by an anti-IL-6 antiserum and an anti-IL-6 receptor transducer chain (gp130) mAb in a dose-dependent manner. This implies that MM5.1 cells are IL-6 responsive only when exposed to one or more additional soluble factor(s) derived from bone marrow stroma. Coculturing MM5.1 cells with IL-6 and cytokines that were described to increase the IL-6 responsiveness of myeloma cells (G-CSF, GM-CSF and IL-3) had no effect on the growth or survival. A strong proliferative effect was observed when MM5.1 cells were cultured with IL-6 and soluble IL-6 receptor (sgp80). However no sgp80 could be detected in stromal supernatants using a sensitive immunoassay. This indicates that sustained proliferation of the MM5.1 cell line depends on a combination of IL6 and at least one, thus far unidentified, stroma-derived factor. After more than 1 year in continuous culture, we could obtain a variant of the line (MM5.2) that shows an improved growth rate and grows stroma independently. Molecular analysis revealed clonal identity with the early passage form and Epstein-Barr virus antigen expression was negative. The two variants of this cell line offer a useful model to identify molecular mechanisms involved in clonal evolution towards stroma-independent growth of myeloma cells.

Functional effects of expression of hslo Ca2+ activated K+ channels in cultured macrovascular endothelial cells.

The aim of the present study is to elucidate the effects of the expression of large conductance Ca2+ activated K+ channels (BK[Ca]) in an endothelial cell type normally lacking this channel. The human homologue hslo of BK(Ca) was expressed in cultured bovine pulmonary artery endothelial (CPAE) cells, which have no endogenous BK(Ca). Membrane potential, ionic currents and Ca2+ signals were investigated in non-transfected and transfected cells using a combined patch clamp and Fura-2 fluorescence technique. In non-transfected control CPAE cells, ATP evoked a Ca2+ activated Cl- current (I[Cl,Ca]). The most prominent current component during ATP stimulation in hslo expressing cells was conducted BK(Ca) which resulted in a pronounced transient hyperpolarization. This hyperpolarization, which was absent in non-transfected cells, was enhanced if I(Cl,Ca) was blocked with niflumic acid. The sustained component of the Ca2+ response during ATP stimulation was significantly larger in hslo transfected cells than in non-transfected cells. This plateau level correlated well with the corresponding effects of ATP on the membrane potential, indicating that the expression of cloned BK(Ca) exerts a positive feedback on Ca2+ signals in endothelial cells by counteracting the negative (depolarizing)effect of stimulation of Ca2+-activated Cl- channels.

The serum resistance-associated (SRA) gene of Trypanosoma brucei rhodesiense encodes a variant surface glycoprotein-like protein.

In the Trypanosoma brucei species, T. b. rhodesiense and T. b. gambiense represent the human infective host range variants, while T. b. brucei is lysed upon exposure to a cytotoxic factor in normal human serum. T. b. rhodesiense can occur in a serum-resistant and a serum-sensitive form. The resistance towards normal human serum was shown to be a labile character and to be determined by the environment in which the parasites live. We have clearly demonstrated the presence of RNA transcripts unique to the resistant forms of T. b. rhodesiense. These transcripts encode a protein with VSG characteristics. The DNA fragment isolated previously, which hybridises with the resistance-specific mRNA sequence, appears to be a pseudogene belonging to the same gene family.

Human serum-sensitive Trypanosoma brucei rhodesiense: a comparison with serologically identical human serum-resistant clones.

Trypanosoma brucei rhodesiense clones, which are susceptible to lysis by normal human serum, were isolated from 3 different human serum-resistant clones originally derived from strain ETat 1.10. Serologically, these pairs of serum-sensitive and serum-resistant clones displayed the same variant surface glycoprotein (VSG) on their surface. Acquisition of human serum sensitivity correlated with susceptibility to lysis by human high density lipoprotein, a trypanocidal factor in normal human serum. Analysis of these paired populations by two-dimensional gel electrophoresis of whole trypanosomes and various subcellular fractions failed to reveal any differences in mobility of VSG and other proteins. Northern blot analysis of mRNAs from serum-sensitive and serum-resistant clones showed no differences when probed with a previously described resistance-specific probe. In addition, the ethanolamine membrane transport system and the overall membrane lipid fluidity did not reveal any detectable biochemical or biophysical differences in membrane properties. If resistance to lysis is indeed mediated by membrane changes at the enzymatic or structural level, the data presented suggest that the gene product(s) responsible for this change in human serum sensitivity may be present in very small quantities.

A gene expressed only in serum-resistant variants of Trypanosoma brucei rhodesiense.

The human infective African trypanosomes are host range variants of Trypanosoma brucei which are resistant to a lytic component in primate serum. T. b. rhodesiense occurs both as a form sensitive to lysis by normal human serum and as a form resistant to this lysis. Switching from one phenotype to the other has been observed in both directions. In the cloned T. b. rhodesiense ETAR1-repertoire we have detected 1.5-kb mRNAs only present in the resistant forms. In T. b. gambiense, which always occurs as a normal human serum-resistant form, no such transcript could be detected, indicating that another mechanism of resistance is involved here. Starting from an independent non-cloned T. b. rhodesiense population isolated from an infected patient, both resistant and sensitive trypanosomes have been prepared. Northern blot analysis of the total RNA prepared from these populations has revealed again the differential occurrence of the resistance-specific transcript, indicating that we are dealing with a general phenomenon associated with serum resistance in T. b. rhodesiense. As expected, Southern blot analyses have demonstrated that both serum-resistant and serum-sensitive forms of T. b. rhodesiense contain the gene coding for this transcript.

Distribution of the organellar Ca2+ transport ATPase SERCA2 isoforms in the cat brain.

Of the three genes encoding the Ca2+ transport ATPases of the endoplasmic reticulum, the SERCA2 gene is the major isoform expressed in the mammalian brain. The SERCA2 transcript is alternatively processed generating two protein isoforms: SERCA2a which is expressed in cardiac and slow-skeletal muscle, and SERCA2b, the house-keeping isoform which is ubiquitously expressed. We have studied the expression of SERCA2 in the cat brain, and at a less refined level also in the rat brain, using antibodies specific for either SERCA2a or SERCA2b. The SERCA2a staining was very restricted. The SERCA2a antibody clearly labeled the cell body of the Purkinje neurons and weakly stained the giant cells of the gigantocellular reticular nuclei. In contrast, the SERCA2b isoform was found in most regions of the brain. It appeared to be largely confined to neuronal cells. Neuroglial cells were negative. The antibody stained the cell body. In heavily labeled cells such as the pyramidal cells of the hippocampus and of the cerebral cortex, it also stained the proximal portion of the dendrites. The most intense labeling was observed in the Purkinje neurons, which were stained all over the cell including the distal ramifications of the dendritic tree. Remarkably the SERCA2b labeling in neuronal cells of the hypothalamic area and the substantia nigra was very weak. The possible physiological significance of these results is discussed.

The clonogenic precursor cell in multiple myeloma.

Multiple myeloma is characterized by the monoclonal expansion of plasma cells in the bone marrow. Although the predominant cell type is the plasma cell, the initial oncogenic transformation is considered to take place in a more immature B cell. There is still much controversy about this precursor cell type. Phenotypic analysis of bone marrow and peripheral blood revealed that in multiple myeloma a great diversity exists in the phenotype of the cells considered to be involved. Because of the lack of a myeloma specific genetic lesion it is very difficult to trace back the cell in which the transforming event, leading to multiple myeloma, took place. The only real clonal marker is the idiotype of the immunoglobulin molecule expressed by the myeloma cells. With recombinant DNA technology it is now possible to produce clonal markers for each individual myeloma patient which recognize only the immunoglobulin genes expressed by the myeloma cell and its precursors. The sequences of these myeloma immunoglobulin genes do reveal a lot of information about the stage in the B-cell differentiation pathway in which the oncogenic event might have taken place. The presence of somatic mutations in a non-random fashion without intraclonal variation leads to the conclusion that the precursor myeloma cell could not possibly be a pre-B cell or stem cell but has to be a mature B cell that has been in contact with antigen and has past through the phase of somatic mutation, like a memory B cell or plasmablast.(ABSTRACT TRUNCATED AT 250 WORDS)

Homing behaviour of the malignant cell clone in multiple myeloma.

Multiple myeloma (MM) represents a B cell malignancy characterised by the presence of a monoclonal population of end-stage B cells in the bone marrow. Although fully matured bone marrow plasma cells are the predominant cell type in MM, there is much evidence that also more immature B cells are included in the malignant cell clone which are considered to be the myeloma precursor cells. The fact that these cells are detectable in the blood circulation and that their number increases with disease progression, makes it very likely that they represent the component of the tumour clone that mediates disease dissemination. This implies that these cells must have the potential to extravasate and home to the bone marrow environment. Like the migration mechanisms used by normal leukocytes and/or metastatic tumour cells of non-haematopoietic origin, it can be assumed that this bone marrow homing process is mediated by adhesive interactions and chemotactic signals provided by the microenvironment of the tumour. Once in the bone marrow compartment, myeloma cells will receive the appropriate signals to grow and survive. This aspect of tumour-homing is found to be the result of a functional interplay between the myeloma cells and the surrounding microenvironment, involving the action of several cytokines and adhesion molecules. In the end phase of the disease, myeloma cells can lose their stroma-dependency resulting in extramedullary tumour growth. We review normal B cell homing and discuss molecular mechanisms that determine the homing behaviour of the malignant cell clone in MM.

[Problems associated with long-term anticoagulant therapy (author's transl)]. / Incidents de l'anticoagulation à long terme.

Two hundred and forty-six patients, a total of 7,614 months of anticoagulant therapy, are studied for complications. Grave problems occurred 4 times (1.6%). The total of major and minor problems was as high as 18%.

Giant phyllodes tumour of the breast.

Phyllodes tumours are fibroepithelial lesions and count for 0.4% of breast tumours. Telling the difference between phyllodes tumours and fibroadenomas is sometimes difficult but of importance because wide resection is the mainstay of treatment for phyllodes tumours. We present a female patient, 55 years old with a giant phyllodes tumour (38 x 31 x 23 cm) of the breast. The breast reconstruction was done using a pedicled transverse rectus abdominis myocutaneous (TRAM) flap.

[Vertical reduction mammaplasty for gigantomastia with massive fibroadenomatosis: a case report]. / Réduction mammaire selon la technique verticale pour gigantomastie avec fibroadénomatose massive: à propos d'un cas clinique.

Vertical reduction mammaplasty is one of the most debated << short-scar >> breast reduction technique. Advantages and drawbacks of the technique are discussed; most of the authors do not accept it as the technique of choice for high glandular resection weights. In our case report we achieve it for a resection weight up to two kilograms with an areolar transposition distance of more than ten centimetres. We show that it is reasonable to realize it dealing with gigantomastia. The massive fibroadenomatosis is observed following immunosuppressive treatment for kidney transplantation. Cyclosporine intake, even sporadic, is at the origin of the growth of these multiple, bilateral and large fibroadenomas. Drug-induced cytokines stimulate their development.

[Breast reconstruction by DIEP free flap: about 100 cases]. / Reconstruction mammaire par lambeau DIEP: à propos de 100 cas.

Autologous breast reconstruction was stigmatised because the muscular sacrifice of the rectus abdominis muscle. This problem could be avoided by the DIEP flap as much for immediate as delayed reconstruction with the creation of an aesthetic and natural shaped reconstructed breast. This retrospective study about 100 cases performed between January 1997 and June 2002 concern 94 patients, 88 unilateral reconstructions and six bilateral. The reconstruction was delayed in 83%, immediate in 8% or realised after failed attempt to reconstruct the breast with implant in 9%. Risk factors were also present: smokers (66%), one or more abdominal scars (40%), obesity (30%). The recipient vessels were the internal mammary vessels (86%), the circumflex scapular vessels (10%) and the subscapular vessels (4%). We noted four total flap loss, 5% of partial loss and 2% localized liponecrosis. Mean operating time was 6 hours 28 minutes for unilateral reconstruction and 9 hours 30 minutes for bilateral reconstruction. Mean hospital stay was 7,3 days. Two moderated abdominal bulging were noted. The tedious dissection of small vessels of the DIEP flap allowed for a similar rate of complication as the free TRAM flap, by respecting of the integrity of the rectus abdominis muscle, to reduce morbidity of harvest with less postoperative pain, shorter hospital stay and faster recovery.

[Forum: reconstruction of the traumatic thumb. Pollicization in the traumatic thumb reconstruction]. / Forum: la reconstruction du pouce traumatique. Les pollicisations dans la reconstruction du pouce traumatique.

The authors present a technical review of 25 pollicisations and define the indications based on their own experience. Pollicisation remains a good solution to restore the function of the adult thumb after injury sparing functional integrity and enhancing the value of stumps.

[Low flow venous malformations in children]. / Malformations veineuses à bas débit de l'enfant.

Low flow venous malformations in children are a diagnostic and therapeutic challenge. They are present at birth but may not be evident; they have a commensurate growth. They are pure or combined (capillary or lymphatic-venous). At examination, one observed soft, compressible bluish swellings; there is no thrill or bruit. They are slow flow anomalies with venous stasis which may induce thrombosis or localized consumptive coagulopathy. Skeletal distortion or bony hypertrophy or hypoplasia may also be observed; histological examination of surgical specimen reveals infiltration of adjacent structures (skin, bone, muscle); ultrasonography and duplex-Doppler may be helpful in differentiating the venous malformation from lymphatic or arteriovenous anomalies. Diagnosis from hemangioma will be obtained by magnetic resonance imaging; this last investigation will also provide informations on the infiltration of the adjacent tissues by the pathologic process. Standard X ray may show phleboliths of skeletal distortion. Most of venous malformations are asymptomatic and treatment consists in reassuring the child and in giving advice to the parents to prevent trauma to the lesion. Conservative treatment must be advocated (compression garments, prevention of thrombosis with salicylates) since total excision of venous malformation is illusory and postoperative morbidity may be important. Surgical excision of limited cumbersome malformations may be indicated; sclerotherapy of the lesion with Ethibloc makes surgery easier.

[Report of 243 vertical mammoplasties for very large, heavy breasts and/or severe ptosis. Analysis of the result and technical]. / A propos de 243 plasties mammaires verticales pour hypertrophie et/ou ptôse importantes. Etude rétrospective, analyse des résultats et description des modifications techniques.

Vertical mammaplasties for very large breasts and/or severe ptosis were evaluated in 124 patients who underwent operation in our unit between September 1993 and June 2001. In 119 cases it was reduction mammaplasty and in 5 cases unilateral symmetrization after contralateral reconstruction. The mean age was 36 years (13-62 years). Among inclusion criteriae, we choose the resection weight > or = 700 g and/or a ptosis > or = 30 cm. We report a few technical modifications of the initial Lejour vertical technique. About hypertrophic breasts (179 breasts): mean resection weight was 905 g (710-1750 g), mean ptosis was 33.5 cm (30-42 cm). The following complications were noted: 3 haematomas with only one evacuation on the same day, no seroma, 4 infections controlled by local treatment, 44 wound dehiscence or delayed skin healing (> 30 d), 8 partial necrosis, 12 secondary correction under local anaesthesia, 1 cheloïd scar of the areolar complex. About breasts with severe ptosis (64 breasts): the mean value was 31.8 cm (30 cm). Complications were as follow: 2 haematoma, 0 seroma, 16 healing delay, 3 partial necrosis, 6 secondary correction under local anaesthesia. The mean procedure time was 94 mn. The mean stay in hospital was 2.8 days, same as the suction drains. The vertical mammaplasty is a fast technique, giving good results. Scarring amount is reduced. Breasts are well projected, well shaped and remain stable in time. Their base can be modified. We think this technique can safely be applied to large breasts and/or severe ptosis.

Homing mechanisms in the etiopathogenesis of multiple myeloma.

Although multiple myeloma (MM) is characterized by a monoclonal expansion of plasma cells, it has been assumed that the tumor clone also includes more immature B cells. We could demonstrate by DNA sequence analysis of the variable region in immunoglobulin (Ig) heavy chain genes, that myeloma patients have peripheral blood monoclonal B cells that have not switched their Ig isotype but are somatically hypermutated. This finding suggests that myeloma originates from a germinal center B cell of the lymph node, most probably a memory B cell or B lymphoblast. The identification of these cells in the peripheral blood circulation implies that they must be equipped with homing receptors that allow them to migrate from the lymph node to the marrow environment. Within the marrow compartment these precursors will receive the appropriate differentiation signals to become mature tumor cells. The growth and survival of these bone marrow (BM) plasma cells is believed to be regulated by a functional interplay with the surrounding marrow stroma involving different adhesive mechanisms and the action of several cytokines. We found that myeloma plasma cells express several adhesion molecules (ICAM-1, N-CAM, CD44, VLA-4). Myeloma cell lines can bind to purified fibronectin (FN) using mostly the VLA-4 receptor. However this interaction contributes only partially to binding with intact stromal layers. In contrast, the post-HDM aplasia was significantly shortened in two of the schedule B patients (3 to 10 days) and was followed by a 25- to 165-fold increase in CD34+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Only the serum-resistant bloodstream forms of Trypanosoma brucei rhodesiense express the serum resistance associated (SRA) protein.

The Trypanosoma brucei species consists of three subspecies. T. b. rhodesiense and T. b. gambiense are human infective forms, while T. b. brucei is lysed upon exposure to the cytotoxic factor in normal human serum. T. b. rhodesiense can however occur as a serum-resistant (R) and as a serum-sensitive form (S). In a study of the molecular basis of serum resistance in T. b. rhodesiense it was shown that in the cloned ETaR1-repertoire only the serum-resistant variants express specific transcripts, encoding a protein with VSG-characteristics. When a serial of freshly isolated T. b. rhodesiense isolates was tested, the presence of the R-transcripts in the serum-resistant populations was confirmed. The absence of the serum resistance associated (SRA) mRNAs in several isolates from T. b. brucei and especially T. b. gambiense (including an a-typical one), indicates that more than one mechanism might be involved in the phenomenon of serum resistance in the T. brucei group. Neither T. evansi, nor T. equiperdum expresses the SRA-transcripts. Interestingly, the transcription of the R-specific transcripts is not maintained during the life cycle of T. b. rhodesiense; in the procyclic forms the SRA-mRNAs are no longer present.

Production of fibronectin and adherence to fibronectin by human myeloma cell lines.

In the present study we examined the production of fibronectin (FN) in 10 human myeloma cell lines (HMCL). By Northern blot analysis we could detect the presence of FN-mRNA in most of these lines. A majority of the cell lines (LP-1, OPM1, SKMM-2, EJM, JJN3 and ARH-77) hybridized with two probes recognizing total FN while the mRNA of one cell line (LB84-1) was shown to hybridize also with a probe recognizing the EDA segment of cellular FN. In one cell line (L363) FN-mRnA could only be detected after PCR amplification. Using an enzyme-linked immunosorbent assay, we could also demonstrate that HMCL secrete FN in their culture medium. Seven myeloma cell lines that produce FN showed a significant adherence to soluble FN. By blocking experiments, this adhesion was found to be mediated by the VLA-4 (alpha 4 beta 1) receptor. The production of fibronectin and the expression of a functional receptor for this protein may represent independent features of myeloma cells but may also be functionally linked. Since fibronectin has recently been identified as a crucial co-factor of IL6 in the regulation of the terminal B cell differentiation, the endogenous FN production may be part of an autocrine-line process mediating the autonomous growth of these cell lines. Alternatively, the FN production may also reflect a mechanism that myeloma cells use to communicate with their natural environment, i.e. the bone marrow stroma.(ABSTRACT TRUNCATED AT 250 WORDS)