Quantification of push-off and collision work during step-to-step transition in amputees walking at self-selected speed: Effect of amputation level.

Maintaining forward walking during human locomotion requires mechanical joint work, mainly provided by the ankle-foot in non-amputees. In lower-limb amputees, their metabolic overconsumption is generally attributed to reduced propulsion. However, it remains unclear how altered walking patterns resulting from amputation affect energy exchange. The purpose of this retrospective study was to investigate the impact of self-selected walking speed (SSWS) on mechanical works generated by the ankle-foot and by the entire lower limbs depending on the level of amputation. 155 participants, including 47 non-amputees (NAs), 40 unilateral transtibial amputees (TTs) and 68 unilateral transfemoral amputees (TFs), walked at their SSWS. Positive push-off work done by the trailing limb (WStS+) and its associated ankle-foot (Wankle-foot+), as well as negative collision work done by the leading limb (WStS-) were analysed during the transition from prosthetic limb to contralateral limb. An ANCOVA was performed to assess the effect of amputation level on mechanical works, while controlling for SSWS effect. After adjusting for SSWS, NAs produce more push-off work with both their biological ankle-foot and trailing limb than amputees do on prosthetic side. Using the same type of prosthetic feet, TTs and TFs can generate the same amount of prosthetic Wankle-foot+, while prosthetic WStS+ is significantly higher for TTs and remains constant with SSWS for TFs. Surprisingly and contrary to theoretical expectations, the lack of propulsion at TFs' prosthetic limb did not affect their contralateral WStS-, for which a difference is significant only between NAs and TTs. Further studies should investigate the relationship between the TFs' inability to increase prosthetic limb push-off work and metabolic expenditure.

Compensatory mechanism involving the hip joint of the intact limb during gait in unilateral trans-tibial amputees.

Hip dynamics in the intact limb during the beginning of stance phase in unilateral trans-tibial amputees (TTA) was studied to evaluate its contribution to compensatory function. We hypothesized (1) an increase in hip total work during H1 power phase (0-30% of gait cycle) including an initial negative phase and (2) an intensification of the hip work in response to uncomfortable gait induced by prosthesis misalignment. Three-dimensional gait analysis was conducted in 17 unilateral TTA and 15 healthy subjects walking at the same self-selected speed in three prosthetic alignments: initial alignment (IA); IA altered either by 6 degrees of internal rotation (IR) or by 6 degrees of external rotation. Patients reported best comfort of gait in IA condition and discomfort mainly in IR condition. During the H1 power phase, in intact limbs a consistent initial flexion movement of the hip (0-8% gait cycle) was associated to negative work and was followed by hip extension and positive work whereas in both prosthetic and control limbs only hip extension and positive work occurred (except in one healthy individual). Absolute value of hip work during H1 phase was significantly higher in intact and prosthetic limbs compared to control limbs in IA condition and was further significantly increased in IR condition only in intact limbs demonstrating a compensatory function of the latter. In intact limbs, early hip negative work contributed to energy absorption in addition to the knee joint probably to compensate the lower energy absorption exerted by the prosthetic limbs.

Compensatory mechanism involving the knee joint of the intact limb during gait in unilateral below-knee amputees.

This study evaluated the asymmetry of knee kinetics during uncomfortable gait induced by prosthesis misalignment to further demonstrate the compensatory function of the knee joint of the intact limb during gait. Three-dimensional gait analysis including knee kinematics and kinetics at the beginning of stance phase was conducted in 15 healthy subjects and 17 unilateral trans-tibial amputees (TTA) walking at self-selected speed in three conditions of prosthetic alignment: initial alignment (IA); initial alignment altered either by 6 degrees of internal rotation (IR) or by 6 degrees of external rotation (ER) applied on the pylon. Patients reported best comfort of gait in IA condition and discomfort mainly in IR condition. Maximum knee flexion and knee total work at power phases K0-K2 were significantly higher in intact limbs compared to prosthetic and control limbs. In intact limbs, these variables had significantly higher values (+10-35%, p<0.05) in IR condition than IA condition whereas these were not altered across conditions in prosthetic limbs. In trans-tibial amputees, inducing uncomfortable gait by internally rotating the prosthetic foot did not alter the knee kinetics of the prosthetic limb, which suggests a protective mechanism. Knee kinetics of the intact limb did alter, which suggests a compensatory mechanism.

[Exercise training for lower limb amputees]. / Le réentraînement à l'effort chez l'amputé de membre inférieur.

Lower limb amputee have lower exercise capacities, proportionally to the delay necessary to use their well-fitted prosthesis. Exercise training is a valid therapeutic to improve local factors (residual limb), muscle strength and endurance, locomotor performance and to decrease the cardiovascular risk factors. The programs for exercise training used for amputees are derivate from the vascular diseases and adapted (upper limb ergometer, cycloergometer with intact limb, pharmacological stress). Exercise training must be personalised because the population with lower limb amputation is very heterogeneous for deficiency and capacity (orthopaedic, vascular and cardiac) and for their socioprofessional project.

[Muscles of the below-knee amputees]. / Les muscles de l'amputé tibial.

OBJECTIVE: The objective of this article is to review anatomical, histological and physiological muscle changes following below-knee amputation. MATERIALS AND METHODS: We searched the PubMed and Reedoc databases for studies evaluating modifications of the below-knee stump and changes over time in its anatomy, volume and histology. We also looked at postamputation modifications in gait and balance. RESULTS: Below-knee amputees show muscular atrophy on both the amputated side and nonamputated side, with fewer and smaller muscle fibres (particularly slow-twitch fibres). This amyotrophy varies in magnitude and distribution and can reach about 25% for the quadriceps (predominantly on the medial side), but is nonsignificant for the hamstrings. This amyotrophy results from the anatomical consequences of the surgical act. The loss of one or more of a muscle's insertions or reimplantation into a nonphysiological site prompts greater atrophy. Changes in muscle activation patterns also lead to atrophy. The hamstrings replace the triceps as the main muscles for propulsion and the remaining stump muscles contract so as to ensure a good fit with the prosthesis. The below-knee amputee must adapt to a new muscular state: gait symmetry is altered, energy expenditure for walking is higher and training is needed in order to achieve optimal balance control.

A High-throughput Screening of a Chemical Compound Library in Ovarian Cancer Stem Cells.

BACKGROUND: Epithelial ovarian cancer has a poor prognosis, mostly due to its late diagnosis and the development of drug resistance after a first platinum-based regimen. The presence of a specific population of "cancer stem cells" could be responsible of the relapse of the tumor and the development of resistance to therapy. For this reason, it would be important to specifically target this subpopulation of tumor cells in order to increase the response to therapy. METHOD: We screened a chemical compound library assembled during the COST CM1106 action to search for compound classes active in targeting ovarian stem cells. We here report the results of the high-throughput screening assay in two ovarian cancer stem cells and the differentiated cells derived from them. RESULTS AND CONCLUSION: Interestingly, there were compounds active only on stem cells, only on differentiated cells, and compounds active on both cell populations. Even if these data need to be validated in ad hoc dose response cytotoxic experiments, the ongoing analysis of the compound structures will open up to mechanistic drug studies to select compounds able to improve the prognosis of ovarian cancer patients.

[Capacity and performance: ambulatory monitoring under controlled and real-life conditions]. / Evaluation des capacités et des performances: contribution des monitorages de la locomotion en situation d'exercice et de vie réelle.

OBJECTIVES: To determine the value of ambulatory monitoring in assessing human gait. To describe the sensors, the parameters and the ambulatory devices. MATERIALS AND METHODS: Literature review and practical experience about techniques, principles, objectives and limits. RESULTS: Accelerometry is the main technique for ambulatory monitoring because of its reliability, pertinence of signals and software developed for interpretation. Simultaneous monitoring of heart rate response is clinically relevant. Pedometers and actimeters can answer precise clinical questions about amount of walking activity. CONCLUSION: Ambulatory monitoring during long periods (one day or more) is important, especially for rehabilitation medicine because it measures the actual patient activity performed and participation. The simultaneous monitoring of environmental conditions of activity should improve the interpretation of the data collected.

Expression of retinoid receptor genes and proteins in non-small-cell lung cancer.

BACKGROUND: Retinoids can suppress carcinogenesis in high-risk non-neoplastic bronchial lesions and can reduce the risk of second primary non-small-cell lung cancer (NSCLC). The effects of retinoids are mediated by nuclear receptors, i.e., the retinoic acid receptors (RARalpha, RARbeta, and RARgamma) and the retinoid X receptors (RXRalpha, RXRbeta, and RXRgamma). We investigated whether abnormalities in the in vivo expression of retinoid receptors are observed in NSCLC. METHODS: Expression of retinoid receptors in paired specimens of normal and cancerous tissues from the lungs of 76 patients with NSCLC was studied by use of antiretinoid receptor antibodies (except those against RXRgamma) and immunohistochemistry. RAR messenger RNAs were analyzed by use of in situ hybridization and by reverse transcription-polymerase chain reaction (RT-PCR). Samples were also studied for loss of heterozygosity (LOH) at chromosome 3p24. All P values are two-sided. RESULTS: All studied receptors were expressed in normal lung cells and in high- risk non-neoplastic lesions. In tumor cells, overexpression of RXRalpha and RARalpha was frequently observed. In contrast, RXRbeta expression decreased in 18% of the tumor specimens. Furthermore, there was a marked decrease in the expression of RARbeta in 63% of the tumors (P<.0001). Decreased expression of RARgamma was observed by RT-PCR in 41% of the tumors (P<.0001). LOH at 3p24 was observed in 41% of the tumor specimens from informative patients and in 20% of the non-neoplastic lesions. CONCLUSIONS: Expression of RARalpha and RXRalpha is either normal or elevated in NSCLC. In contrast, a large percentage of tumors show a marked decrease in the expression of RARbeta, RARgamma, and RXRbeta as well as a high frequency of LOH at 3p24, which was also observed in non-neoplastic lesions. These data suggest that altered retinoid receptor expression may play a role in lung carcinogenesis.

[Optoelectronic gait analysis after metatarsophalangeal arthrodesis of the hallux: fifteen cases]. / Analyse opto-électronique de la marche après arthrodèse métatarso-phalangienne de l'hallux: à propos de 15 cas.

PURPOSE OF THE STUDY: Degeneration of the metatarsophalangeal joint of the hallux is a frequent secondary lesion of the first ray subsequent to hallux valgus. Different surgical techniques have been proposed for cure, including metatarsophalangeal arthrodesis. Joint fusion relieves pain but sacrifices joint motion. The purpose of this work was to assess changes observed in gait after metatarsophalangeal arthrodesis of the hallux using a three-dimensional optoelectronic system. MATERIAL AND METHODS: Gait analysis was performed with a Vicon 3D system with five cameras and two AMTI force platforms in twelve patients who had undergone metatarsophalangeal arthrodesis more than six months earlier. The kinetic and kinematic curves and ground reaction forces were analyzed. Changes in the gait cycle and any compensations observed in the talocrural and interphalangeal joints were noted in the three dimensions. Wilcoxon test for paired series was applied for the statistical analysis. RESULTS: The general gait parameters and kinetic and kinematic values were not modified (excepting a non-significant decline in maximal dorsiflexion of the ankle joint). There was a significant decrease in propulsion force in the anteroposterior and vertical planes, with significantly later heal lift-off and systematic displacement of ground reaction forces anterior to the metatarsophalangeal joint on the arthrodesis side. Reflectors positioned on the distal extremity of the hallux demonstrated that the essential part of compensation occurred at the level of the interphalangeal joint. DISCUSSION: Gait analysis after tibiotalar arthrodesis has been widely reported in the literature. The consequence of joint fusion on the rear foot and/or the torsion couple have also been studied. However, to our knowledge, there has been only one report using a different methodology devoted to metatarsophalaneal arthrodesis of the hallux. In this study, only step length and interphalangeal moment as well as ankle force were found to be decreased. Function of the interphalangeal joint was not assessed. The Vicon system enabled an adapted study of gait after metatarsophalangeal arthrodesis. This method offers several perspectives: study of the effect of the position of the arthrodesis in the sagittal plane on gait, changes over time in interphalangeal joint motion, or consequences of fusion on walking up and down stairs. CONCLUSION: Metatarsophalangeal arthrodesis of the hallux does not modify general gait parameters nor the kinetic and kinematic values. Compensation is achieved via the interphalangeal joint.

The role of platelet-derived growth factor production by tumor-associated macrophages in tumor stroma formation in lung cancer.

Lung cancer is the most common cause of death by cancer in developed countries. Since a tumor cannot develop without the parallel expansion of a tumor stroma, a better understanding of its formation could lead to new therapeutical approaches. In this respect, since platelet-derived growth-factor (PDGF) is a chemotactic and growth factor for mesenchymal and endothelial cells, lung tumors of patients undergoing surgery for non-small cell lung cancer were evaluated for their replication rate using iododeoxyuridine incorporation, and for the expression of PDGF genes and the presence of PDGF A and B chains and of PDGF receptor alpha and beta subunits. This observation demonstrates that: (a) tumor cells and stroma mesenchymal cells, but not tumor-associated macrophages, display a high replication rate; (b) 1 of 3 tumors are characterized by cancer cells expressing the genes for PDGF A and/or B chains, while 1 of 2 tumors are composed of tumor cells presenting PDGF receptors alpha and beta subunits on their surface, and in only 1 of 6 tumors, tumor cells coexpress PDGF and its receptor; (c) in almost all tumors, tumor-associated macrophages express PDGF A and/or B chain genes; (d) mesenchymal cells, as well as endothelial cells, do not express PDGF A and B chain genes but do express PDGF receptor alpha and beta subunits; and (e) an ongoing active process was suggested in the periphery of the tumor by the simultaneous strong expression of PDGF A and B chain genes by tumor-associated macrophages and the high replication rate of mesenchymal and endothelial cells in the same area. Thus, PDGF is likely to have a limited autocrine role in tumor cell replication but is a potential player, in a paracrine fashion, in tumor stroma development.

Retinoic acid receptor and retinoid X receptor alterations in lung cancer precursor lesions.

Smoking prevention will decrease lung cancer incidence in time. However, early detection would improve lung cancer prognosis in subjects at risk provided that specific markers could be identified. We previously reported that retinoic acid receptor (RAR) and retinoid X receptor (RXR) expression was altered in lung tumors. RAR-beta gene status could be derived from corresponding allelotyping and immunohistochemistry data. We now report the continued study on lung cancer precursor lesions. Fluorescence PCR-based assays were used for allelotyping at the RAR/RXR loci of: (a) 66 lung precursor lesions found at the free resection margins of 41 patients undergoing surgery for lung cancer (+ 31 paired tumors); and (b) bronchial cells also found at the free resection margins from 16 current and 8 never smokers operated on for noncancerous diseases. Three microsatellites located at 3p14-21 and 9p21 were also used for interwork comparison. Immunohistochemistry was additionally performed to evaluate P53 and RAR-beta expression in precursor lesions. Chi2 tests showed significant differences (P < 0.05) when comparing the results obtained from never smokers, smokers, squamous metaplasia, dysplasia + in situ carcinoma, and tumors. Microsatellite changes occurred frequently in all samples, but without specificity for any group (P < 0.08-0.52). They were globally correlated with tobacco exposure (P < 0.04), for which the RAR-gamma marker appeared as a preferential target (P < 0.004). Few reparation error phenotypes were observed, mostly at the RXR-alpha and RXR-gamma markers for which combined changes were also linearly increasing from never smokers to dysplasia + in situ carcinoma (P < 0.05 and P < 0.03). RAR-beta marker losses also increased from the first to the last group studied (P < 0.01), with a concomitant decrease in RAR-beta protein expression and correlated p53 increased immunoreactivity (P < 0.02). Losses at 3p14, 3p21, and P16 were frequent, but no significant differences between groups could be found. Unexpectedly, high constitutive homozygosity was observed near the RAR-alpha locus in squamous cell lung cancer cases. RARs/RXRs form homodimers or heterodimers involved in ligand binding. Their added alterations could result in a state of functional vitamin A deficiency in the affected bronchial cells. Further deletion events drawn from a limited repertoire of specific regions such as 3p14-21 and 9p21 could subsequently drive the deficient cells to invasive carcinoma.

Phantom hand and wrist movements in upper limb amputees are slow but naturally controlled movements.

After limb amputation, patients often wake up with a vivid perception of the presence of the missing limb, called "phantom limb". Phantom limbs have mostly been studied with respect to pain sensation. But patients can experience many other phantom sensations, including voluntary movements. The goal of the present study was to quantify phantom movement kinematics and relate these to intact limb kinematics and to the time elapsed since amputation. Six upper arm and two forearm amputees with various delays since amputation (6months to 32years) performed phantom finger, hand and wrist movements at self-chosen comfortable velocities. The kinematics of the phantom movements was indirectly obtained via the intact limb that synchronously mimicked the phantom limb movements, using a Cyberglove® for measuring finger movements and an inertial measurement unit for wrist movements. Results show that the execution of phantom movements is perceived as "natural" but effortful. The types of phantom movements that can be performed are variable between the patients but they could all perform thumb flexion/extension and global hand opening/closure. Finger extension movements appeared to be 24% faster than finger flexion movements. Neither the number of types of phantom movements that can be executed nor the kinematic characteristics were related to the elapsed time since amputation, highlighting the persistence of post-amputation neural adaptation. We hypothesize that the perceived slowness of phantom movements is related to altered proprioceptive feedback that cannot be recalibrated by lack of visual feedback during phantom movement execution.

Predictive survival markers in patients with surgically resected non-small cell lung carcinoma.

Among patients with resected non-small cell lung carcinoma, about 50% will present a tumor recurrence. Thus, it would be of major importance to be able to predict and try to prevent these relapses by an active chemotherapy and/or radiotherapy. In an attempt to answer this question, the tumors of 227 patients with a surgically resected non-small cell lung carcinoma were evaluated as follows: tumors were classified as squamous cell carcinoma (n = 132) or adenocarcinoma (n = 95), and tumor differentiation was evaluated for each type. Then, all tumors were classified in respect to their pathological TNM staging (WHO) and screened by immunohistochemistry for the detection of the expression of the following antigens: Bcl-2, A+B+H blood group antigens, c-erb-b2, p53, and Pan-Ras antigens. Furthermore, adenocarcinomas were screened for the presence of point mutations in Ki-Ras codons 1-31. Finally, the patient blood group was defined, and patient survival was analyzed using nonparametric tests and proportional hazard Cox models. Using Kaplan-Meier survival curves, disease pathological TNM staging was shown to be a strong predictive factor of survival for both squamous cell carcinoma and adenocarcinoma. Patients with squamous cell carcinoma experienced fewer relapses than those with adenocarcinoma (42% versus 63%; P = 0.0002) and had a significantly better survival. All evaluated antigens were more often present in squamous cell carcinoma than in adenocarcinoma except for Pan-Ras (three times more frequent in adenocarcinoma). In patients with squamous cell carcinoma, only tumor staging had a significant prognosis value (P = 0.01). In patients with lung adenocarcinoma, a well-differentiated tumor (P = 0.009) as well as a positive Bcl-2 staining (P = 0.009) and an A+B+H antigen tumor staining (P = 0.024) were associated with a better survival. In contrast, patients with a stage I or II disease and a p53-positive tumor staining and patients with the O blood group (P = 0.01) had a shorter survival. Interestingly, no relation with patient survival was related to c-erb-b2 and Pan-Ras staining. Finally, 12 point mutations were found out of 81 tumors (15%) evaluated for Ki-Ras codons 1-31; they involved codon 12 but also 8, 14, and 15 without any relationship to survival. In respect to lung adenocarcinoma, using Cox proportional hazard models stratified on tumor staging, the following markers were shown to be related to survival: (a) Independent markers of longer survival (ie., high histological degree of tumor differentiation and positive Bcl-2 and A+B+H blood group antigen expression by tumor cells); and (b) Independent markers of shorter survival (i.e., O blood group for all patients and p53 tumor staining in patients with stage I and II diseases). This study suggests that, in patients who undergo surgery for lung adenocarcinoma, the presence or absence of these criteria could be used to define a subset of patients who may benefit from a more specific follow-up.

[Evaluation of amputees]. / Evaluation des amputés.

INTRODUCTION: Review of the literature about evaluation of amputees. MATERIALS AND METHODS: A search of the Medline and Reedoc databases with the key words lower limb amputee, upper limb amputee, evaluation of lower limb amputee, evaluation of upper limb amputee, survey of lower limb amputee, survey of upper limb and the same words in French for reports on the evaluation of amputees. RESULTS: Evaluations of amputees differ according to the level of amputation (lower or upper limb) and age (adult or child). They concern standing balance, walking (lower limb) and the mono- or bimanual prehensile capacities with or without prostheses in daily living activities and leisure (upper limb) as well as quality of life, personal satisfaction, psychological impact and, in particular, coping strategies. DISCUSSION: For lower-limb amputees, tools to evaluate include scales of deambulation, of which few are valid in French, and global scales (on locomotor capacities, quality of life and satisfaction), which have been recently validated, but only one of them is valid in French. For upper-limb amputees, specific and valid tools are not available for adults; however, for children some functional capacity scales in daily activities have been validated and take into account psychomotor development. None of these tools are valid in French, and their use is scattered and limited to validation studies. CONCLUSION: Only a few tools to evaluate amputees are valid in French for adults, and they concern lower-limb amputees only. Validating some of these tools in French is necessary.

Identification and characterization of chemoattractants for epidermal cells.

We have detected and partially characterized factors that promote the directed migration of mouse epidermal cells in a modified Boyden chamber assay. Smooth muscle cells grown in culture were found to secrete a potent chemoattractant for epidermal cells. This activity was further characterized and compared to the chemotactic activities found in wound fluid and conditioned medium from 3T3 L1 cells and with interleukin 1. The migration of epidermal cells during wound healing in vivo might be regulated by such factors.

Cultivation of murine hair follicles as organoids in a collagen matrix.

Techniques are described for the isolation and cultivation of functionally intact mouse hair follicles. Follicles were isolated by collagenase digestion of dermis from 5-day-old mice and purified by differential centrifugation and filtration. Purified follicles were cultured in a Type 1 collagen matrix using Medium 199 and 8% fetal calf serum as the basic nutrient. Viability of follicles was maintained in culture since the cultures incorporated thymidine into DNA and methionine into proteins for at least 7 days. Furthermore, follicles isolated from the collagen matrix after 7 days could reattach to a plastic culture substrate or be further cultivated in a fresh collagen matrix. Functional integrity of cultured follicles was maintained since some follicle-specific cytoskeletal proteins were synthesized in vitro, and follicles isolated from the collagen matrix after 7 days formed a haired skin when recombined with dermal fibroblasts and grafted to a skin site on nude mice. Only a minority of follicles appeared to produce a mature hair shaft in vitro by morphologic criteria, however, and synthesis of the total complement of hair proteins was not observed. Cholera toxin was a strong mitogen for cultured follicles, whereas epidermal growth factor was slightly mitogenic. Epidermal growth factor stimulated the release of a Type 1 collagenase by follicle cells, however. This model system provides an opportunity for the systematic analysis of factors required for the induction of hair growth and the underlying physiology of hair follicle development. This model should also be useful for studying the role of the hair follicle in skin carcinogenesis.

Down-regulation of peroxisome proliferator-activated receptor-gamma gene expression by sphingomyelins.

We recently demonstrated that the sphingomyelin (SM) content of adipocyte membranes was negatively correlated with the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) in the subcutaneous adipose tissue of obese women with variable degrees of insulin resistance. We have now investigated whether SM really does have an impact on the expression of PPARgamma in 3T3-F442A adipocytes. Adding SM to the culture medium for 24 h caused a significant increase in SM content of adipocyte membranes and an acyl chain length-dependent decrease in the levels of PPARgamma mRNA and protein. The longer the acyl chain of the fatty acid of SM, the greater was the decrease in PPARgamma. These data suggest that the nature of the fatty acid is important in the regulation of PPARgamma by the SM pathway.

Differential migratory response of U-2 OS osteosarcoma cell to the various forms of platelet-derived growth factor.

U-2 OS osteosarcoma cells are mesenchymal-derived transformed cells spontaneously expressing both platelet-derived growth factor (PDGF) A- and B-chain genes, and releasing PDGF AA dimers in culture. Using modified Boyden chemotactic chambers, platelet-purified PDGF was shown to be a chemoattractant for U-2 OS cells. More specifically, U-2 OS cells migrated in the presence of PDGF AB and BB dimers but not in the presence of PDGF AA dimers. This pattern of response was similar to that observed with human fibroblasts and this similarity is consistent with the fact that U-2 OS cells express PDGF receptor alpha- and beta-subunits in a similar fashion to human fibroblasts.

Differential expression of PDGF A- and B-chain genes and production of AA and AB dimers by activated human blood monocytes.

Platelet-derived growth factor (PDGF) is composed of two chains (A and B) bound by disulfide bridges. Blood monocytes (BM) express the c-sis proto-oncogene, the gene coding for PDGF B-chain, and release PDGF. To evaluate PDGF release and A- and B-chain gene expression by BM, normal BM were cultured with LPS and specific transcripts for PDGF A- and B-chain genes were detected by Northern analysis and PDGF dimers by specific Elisas. Normal BM did not spontaneously express either A- or B-chain gene while, when activated, PDGF B-chain expression was precocious (maximum at 1 h) and decreased over 24 h; PDGF A-chain transcripts were present after 4 h and progressively increased over 24 h. Furthermore, activated BM released more AB dimers than AA dimers and almost no BB dimers. This observation confirms the concept of PDGF A- and B-chain separate gene regulation, and defines the specific molecular pattern of PDGF released by activated BM.

Blood monocyte chemotaxis.

Migration is a prerequisite for blood monocytes to exert their biological activities, since they have to migrate from blood into the tissues where they transform into macrophages. In vivo chemotaxis of blood monocytes is seldom evaluated, while their in vitro ability to migrate is frequently tested. The most frequently used test relies on BM migration through filters using modified Boyden chemotactic chambers. Using checkerboard analysis it is possible to define chemotactic and chemokinetic factors.