La tomographie par émission de positons au 18fluorodésoxyglucose (18FDG-TEP) dans la prise en charge du cancer bronchique non à petites cellules en 2006

Technological progress and numerous published studies allow to estimate the best place of the 18F-fluorodeoxyglucose positron emission tomography, a real functional metabolic imagery, in the clinical and therapeutic strategy of non small cell lung cancers.

[PET scanning in the initial assessment of lung cancer]

18FDG-PET scanning enables the imaging of metabolic activity giving an assessment of the local extent of thoracic malignancies as well as an indication of the presence of nodal or metastatic spread. This enables more accurate staging and has revolutionised the management of lung cancer. National and international guidelines describe the role of this technique.

[18-FDG positon emission tomography and distal metastasis from lung cancer]

"Whole body" FDG-PET usually covers the body from the base of the skull to the upper third of the thighs, arms in abduction. Thus, the upper part of the head and the lower limbs are not included in the acquisition field. We report the cases of three patients with non-small-cell lung cancer who developed secondary distal localizations beyond the acquisition field of "whole body" FDG-PET. Lung cancer is known to favor hematogenic dissemination, raising the possibility of early distal metastasis. A pretherapeutic PET scan which includes the extremities can be useful to search for distal extension. These true whole body scans are time consuming and can thus limit machine availability. Furthermore, the diagnostic yield of this type of examination may be low since it can be estimated that about 1% of patients will develop isolated distal metastases (3 out of 293 patients in our series initially treated for non-metastatic non-small-cell lung cancer). In the current context of technical availability, systematic inclusion of the lower limbs in the PET scan acquisition field would not appear warranted for the initial work-up of patients with non-small-cell lung cancer. However, clinicians must be aware that distal metastases (brain, lower limbs) may not be detected.

High-Grade Lymphoma of the Bladder Visualized on PET

F-18 FDG PET is used for the staging of many cancers. One of its limits is the analysis of the pelvis and the urinary tract because of physiological radiotracer excretion. We report a rare case of an 82-year-old woman in whom intravenous administration of diuretics (furosemide) allowed the identification of a primary diffuse large B-cell lymphoma of the bladder wall. This pharmaceutical increases urine flow and, therefore, reduces the concentration of radiotracer in the urinary tract, improving the visualization of pelvic or urinary tumors. Furosemide administration is an easy, safe, and noninvasive method, even in case of renal insufficiency. Newer PET cameras with high-performance crystals allow rapid acquisitions and improve the tolerance of an examination with diuretic injection. The 3-dimensional reconstruction of images in new PET cameras reduces the occurrence of hyperactive bladder artifacts. The present case illustrates the advantages of furosemide in a rare pathologic entity.

Developmental progression of immunoglobulin heavy chain diversity in sheep

In order to assess the respective impacts of combinatorial rearrangement, junctional diversification, somatic hypermutation and gene conversion in the generation of immunoglobulin heavy chain variable regions diversity, the sequences of 42 variable regions from late fetal, newborn and young sheep were determined and compared to those of adult animals. At earlier stages of development, the use of germline diversity segments appears restricted, junctional variability is already established, and somatic hypermutations are scarce. The sequence diversity in adults is much higher, which we suggest results from a higher hymermutation activity and possibly from the use of a variety of diversity segments. Altogether, this pattern is very reminiscent of the situation observed in cattle, except for the length of the third complementarity determining regions (CDR3) which are shorter in sheep than in bovine. Unlike the chicken and rabbit systems, it seems that new rearrangements continue to occur in sheep for at least several months after birth.

The role of E-cadherin in nevogenesis: an experimental study using epidermal reconstructs

BACKGROUND

In the development of congenital nevi, how nevus cells migrate in the dermis remains unclear. As shown in an earlier study designed to investigate Unna's Abtropfung hypothesis, dermal invasion does not occur when nevus cells are seeded on epidermal reconstructs. In melanoma, the decrease of E-cadherin expression is associated with the dermal invasion of melanoma cells.

OBJECTIVE

To study the expression of E-cadherin in dermal-cultured nevus cells from congenital nevi and its relevance to explain the absence of dermal invasion noted in epidermis reconstructed with cultured nevus cells.

METHODS

Comparison of the immunohistochemical expression pattern of E-cadherin in congenital nevi in vivo and after culture in monolayers and in a three-dimensional system.

RESULTS

E-cadherin was not expressed in vivo by dermal nevus cells, either isolated or in nests. However, in monolayer cultures, dermal nevus cells expressed E-cadherin. When these cells were used in reconstructed epidermis, nevus cells did not invade the dermis and they expressed E-cadherin when isolated and just weakly or not when grouped in junctional nests.

CONCLUSIONS

The absence of dermal invasion of nevus cells could be due to the expression of E-cadherin in these cells in reconstructed epidermis. Our experiments suggest, a restoration of the control of keratinocytes, that nevus cells escape in the dermal compartment.

The 'Abtropfung phenomenon' revisited: Dermal nevus cells from congenital nevi cannot activate matrix metalloproteinase 2 (MMP-2)

Since Unna's Abtropfung hypothesis, the process of migration of nevus cells in the dermis remains unknown. To investigate its mechanisms, we studied the role of gelatinases in dermal nevus cells obtained from congenital pigmented nevi, which are major actors in the remodeling of basement membrane proteins. Our previous studies have shown that dermal nevus cells express pro-matrix metalloproteinase (MMP)-2 exclusively and cannot return to the dermis when seeded together with keratinocytes on top of the dermis in a skin reconstruction model. To examine why MMP-2 was not in its active form, we used Western blot to study the expression of members of the MMP-2 activation pathway (membrane type 1-MMP and tissue inhibitor of metalloproteinase-2), which proved to be normally expressed. To induce the dermal passage of nevus cells artificially, we also tried to activate gelatinases with phorbol-12-myristate-13-acetate and epidermal growth factor, using epidermis reconstructed with nevus cells. No migration in the dermis could be triggered. We conclude that the absence of active MMP-2 is due to a functional blockade of its activation pathway and may prevent dermal nevus cells from reaching the dermal compartment in skin reconstructs. Furthermore, our findings reinforce the concept that dermal nevus cells originating from congenital nevi are in a quiescent status.

Dermal nevus cells from congenital nevi cannot penetrate the dermis in skin reconstructs

Congenital nevi are composed of pigment cells bearing common features with melanocytes but showing altered differentiation which leads to nesting and dermal involvement. Using a dead de-epidermized dermis seeded with a combination of keratinocytes and various sources of pigment cells (normal melanocytes, dermal nevus cells from congenital nevi, Bowes melanoma cells), we have studied the formation of nests and the dermal migration of pigment cells together with their secretion profiles of matrix metalloproteinases (MMP). Dermal fibroblasts were also used as control cells in epidermal reconstructs. Besides their morphologic features, the absence of pigment donation to keratinocytes was the major characteristic of dermal nevus cells. A positive correlation was established between the increasing percentage of seeded nevus cells and the patchy pigmentation of reconstructs, as well as the clustering of cells in junctional nests. However, the presence of nevus cells in the dermis of reconstructs was never detected, whereas melanoma cells and dermal fibroblasts could invade the dermis during the time span of the experiments. MMP9 was never expressed in congenital dermal nevus cells but pro-MMP2 was constitutively expressed by all strains of congenital nevus cells and dermal fibroblasts. Melanocytes produced comparable amounts of both pro-MMP2 and pro-MMP9, and Bowes melanoma cells secreted a marginal level of pro-MMP2. In view of their three-dimensional behaviour and secretion of MMPs, we propose that dermal congenital nevus cells correspond to an intermediate status of differentiation between normal melanocytes and melanoma cells. Activation of MMPs by a cofactor or the activation of another signalling pathway seems necessary to induce the dermal passage of nevus cells.

Litchi chinensis fatty acid diversity: occurrence of the unusual cyclopropanoic fatty acids

Litchi chinensis (Sapindaceae) is a tree that originates from China and is cultivated for its sweet fruits all over the world in warm climates. Unusual fatty acids such as cyclopropanoic fatty acids have been identified in the seeds of Litchi. Because of their potential value for industry (as inks, cosmetics, detergents, lubricants, etc.), the variability in the relative levels of unusual fatty acids in the seeds of 28 different Litchi varieties was analysed at two locations (on Réunion Island in the Indian Ocean) and on two different harvest dates. Except for one variety, all the seeds contained cis-9,10-methylene-octadecanoic acid (C(19)CA) at a relative level of 35-48%. The only variety that contained no or only traces of C(19)CA was Groff, seeds of which were significantly much smaller than those from all other varieties.

The reconstructed epidermis with melanocytes: a new tool to study pigmentation and photoprotection

The reconstruction of the epidermal melanin unit ex vivo has been achieved during the last decade, using the combination of previous cell culture techniques. The system reviewed is basically a modification of the Pruniéras model, using the air-liquid interface to grow differentiated keratinocytes, with the addition of 5% melanocytes in the seeding suspension, as well as the use of a more adapted culture medium. Repeated UVB irradiation induces a stimulation of melanogenesis macroscopically, and increases melanin concentration and melanosome transfer in reconstructs. These results have been reproduced with skin of various phototypes. This model allows to study the physiology of the epidermal melanin unit as well as pathologic conditions, like vitiligo and nevi. Recent evidence of a complex interaction of keratinocytes and melanocytes in photoprotection was provided by the use of chimeric reconstructs and by comparing autologous reconstructs made with and without low phototype caucasoid melanocytes. Based on these findings, we suggest a novel interpretation of the concept of phototype.

Response surface analysis of chlortetracycline and tetracycline production with K-carrageenan immobilized Streptomyces aureofaciens

A full-factorial experimental design at three levels with two independent variables, carrageenan concentration (1.0, 1.5, and 2.0%) and potassium chloride concentration (0.3, 0.7, and 1.1 M) was studied in order to analyze the effect of both factors on the antibiotic production of K-carrageenan-immobilized mycelia of Streptomyces aureofaciens. The response surfaces obtained have indicated that both carrageenan and potassium chloride concentrations have a pronounced effect on the yield of chlortetracycline (CTC) and tetracycline (TC) produced by S. aureofaciens. By exclusively varying the immobilization conditions, the tetracycline production can be enhanced more than eight times (12.3 mg g-1 biomass for immobilized cells vs. 1.5 mg g-1 biomass for free cells) in comparison with free-cell mycelial cultures.

Inducer effect of Tween 20 permeabilization treatment used for release of stored tropane alkaloids inDatura innoxia Mill. hairy root cultures

The effects of Tween 20 as permeabilizing agent on tropane alkaloids fromDatura innoxia Mill. hairy root cultures have been studied. The kinetics of the alkaloid release is detailed and shows three different stages: an initial rapid increase of the alkaloid level within the roots and in the culture medium, followed by a slower but higher increase of the alkaloid concentration in the medium. During this phase, the alkaloid concentration within the roots returned to a lower value. Finally, after a longer time, the quantity of hyoscyamine in the medium decreased significantly with a variable rate. According to the total alkaloid content per flask determinations under different conditions, it is clearly demonstrated that Tween treatment permeabilized the roots, but also acted as an inducer.

Permeabilization of Datura innoxia hairy roots for release of stored tropane alkaloids

The effects of tween 20 as permeabilizing agent on tropane alkaloids from Datura innoxia Mill, hairy roots have been studied. For various tween 20 concentrations both hyoscyamine and scopolamine accumulated in the culture medium. Plant material viability could be preserved after a 24 hours-2% tween 20 concentration treatment. The time-course study of alkaloid release showed that the maximum of excretion occurred after a 20 hour contact with tween 20. At that time, a concentration of hyoscyamine superior to 25 mg/l was detected in the medium.

Effects of calcium, alginate, and calcium-alginate immobilization on growth and tropane alkaloid levels of a stable suspension cell line of Datura innoxia Mill

A stabilized two-year old suspension of a Datura innoxia cell line, producing small amounts of tropane alkaloids (scopolamine and hyoscyamine) was used in this study. Calcium alginate immobilization has been shown to be able to increase secondary metabolite (i. e. alkaloid) production. The effects of calcium and ungellified alginate were both beneficial for tropane alkaloid synthesis; a 10mM calcium chloride supply gave the best results, with a 10-fold yield increase.

Tropane Alkaloid Levels in the Leaves of Micropropagated Datura innoxia Plants

Three androgenic DATURA INNOXIA Mill. (Solanaceae) plants which had been characterised in regard to their tropane alkaloid levels were micropropagated through axillary buds. The alkaloid contents in the leaves of more than 300 micropropagated plants were investigated by ELISA and HPLC, after one and two culture cycles and compared to those of one of seedlings obtained from the same original line from which the androgenic plants had been produced. The plant with the higher alkaloid level yielded the population with the most alkaloids. After a second cycle of micropropagation, all the populations contained more alkaloids than those they had been derived from. All the micropropagated plant populations contained higher levels of alkaloids than plants grown from seeds.