Identification of TGFß signatures in six murine models mimicking different osteoarthritis clinical phenotypes.

OBJECTIVE: TGFß is a key player in cartilage homeostasis and OA pathology. However, few data are available on the role of TGFß signalling in the different OA phenotypes. Here, we analysed the TGFß pathway by transcriptomic analysis in six mouse models of OA. METHOD: We have brought together seven expert laboratories in OA pathophysiology and, used inter-laboratories standard operating procedures and quality controls to increase experimental reproducibility and decrease bias. As none of the available OA models covers the complexity and heterogeneity of the human disease, we used six different murine models of knee OA: from post-traumatic/mechanical models (meniscectomy (MNX), MNX and hypergravity (HG-MNX), MNX and high fat diet (HF-MNX), MNX and seipin knock-out (SP-MNX)) to aging-related OA and inflammatory OA (collagenase-induced OA (CIOA)). Four controls (MNX-sham, young, SP-sham, CIOA-sham) were added. OsteoArthritis Research Society International (OARSI)-based scoring of femoral condyles and ribonucleic acid (RNA) extraction from tibial plateau samples were done by single operators as well as the transcriptomic analysis of the TGFß family pathway by Custom TaqMan® Array Microfluidic Cards. RESULTS: The transcriptomic analysis revealed specific gene signatures in each of the six models; however, no gene was deregulated in all six OA models. Of interest, we found that the combinatorial Gdf5-Cd36-Ltbp4 signature might discriminate distinct subgroups of OA: Cd36 upregulation is a hallmark of MNX-related OA while Gdf5 and Ltbp4 upregulation is related to MNX-induced OA and CIOA. CONCLUSION: These findings stress the OA animal model heterogeneity and the need of caution when extrapolating results from one model to another.

Les grands exclus face à la pandémie.

Faced with the corona virus pandemic, those leaving in total exclusion of our modern societies express various needs other than food: needs of reference points, communication, care and recognition of human dignity. It is our responsibility to consider these needs as essential.

Fibroblast Growth Factor 23 drives MMP13 expression in human osteoarthritic chondrocytes in a Klotho-independent manner.

OBJECTIVE: Fibroblast Growth Factor 23 (FGF23) may represent an attractive candidate that could participate to the osteoarthritic (OA)-induced phenotype switch of chondrocytes. To address this hypothesis, we investigated the expression of FGF23, its receptors (FGFRs) and co-receptor (Klotho) in human cartilage and studied the effects of rhFGF23 on OA chondrocytes. METHOD: Gene expression or protein levels were analysed by RT-PCR and immunohistochemistry. Collagenase 3 (MMP13) activity was measured by a fluorescent assay. MAPK signalling pathways were investigated by phosphoprotein array, immunoblotting and the use of selective inhibitors. RNA silencing was performed to confirm the respective contribution of FGFR1 and Klotho. RESULTS: We showed that the expression of FGF23, FGFR1 and Klotho was up-regulated at both mRNA and protein levels in OA chondrocytes when compared to healthy ones. These overexpressions were markedly elevated in the damaged regions of OA cartilage. When stimulated with rhFGF23, OA chondrocytes displayed an extended expression of FGF23 and of markers of hypertrophy such as MMP13, COL10A1, and VEGF. We demonstrated that FGF23 auto-stimulation was both FGFR1-and Klotho-dependent, whereas the expression of markers of hypertrophy was mainly dependent on FGFR1 alone. Finally, we showed that FGF23-induced MMP13 expression was strongly regulated by the MEK/ERK cascade and to a lesser extent, by the PI-3K/AKT pathway. CONCLUSION: These results demonstrate that FGF23 sustains differentiation of OA chondrocytes in a Klotho-independent manner.

ERRα promotes breast cancer cell dissemination to bone by increasing RANK expression in primary breast tumors.

Bone is the most common metastatic site for breast cancer. Estrogen-related-receptor alpha (ERRα) has been implicated in cancer cell invasiveness. Here, we established that ERRα promotes spontaneous metastatic dissemination of breast cancer cells from primary mammary tumors to the skeleton. We carried out cohort studies, pharmacological inhibition, gain-of-function analyses in vivo and cellular and molecular studies in vitro to identify new biomarkers in breast cancer metastases. Meta-analysis of human primary breast tumors revealed that high ERRα expression levels were associated with bone but not lung metastases. ERRα expression was also detected in circulating tumor cells from metastatic breast cancer patients. ERRα overexpression in murine 4T1 breast cancer cells promoted spontaneous bone micro-metastases formation when tumor cells were inoculated orthotopically, whereas lung metastases occurred irrespective of ERRα expression level. In vivo, Rank was identified as a target for ERRα. That was confirmed in vitro in Rankl stimulated tumor cell invasion, in mTOR/pS6K phosphorylation, by transactivation assay, ChIP and bioinformatics analyses. Moreover, pharmacological inhibition of ERRα reduced primary tumor growth, bone micro-metastases formation and Rank expression in vitro and in vivo. Transcriptomic studies and meta-analysis confirmed a positive association between metastases and ERRα/RANK in breast cancer patients and also revealed a positive correlation between ERRα and BRCA1mut carriers. Taken together, our results reveal a novel ERRα/RANK axis by which ERRα in primary breast cancer promotes early dissemination of cancer cells to bone. These findings suggest that ERRα may be a useful therapeutic target to prevent bone metastases.

Intracellular localisation of galectin-3 has a protective role in chondrocyte survival.

OBJECTIVE: Although galectin-3 (gal-3) is expressed during arthritic disorders, the part it plays has never been described. The aim of the study was to determine the intracellular roles of gal-3 in chondrocytes and cartilage. METHODS: Following treatment with sodium nitroprusside, a cell death inducer, intracellular levels of total and phosphorylated gal-3 were measured by immunoblots in human osteoarthritic (OA) chondrocytes. Cell viability was also assessed by the lactate dehydrogenase activity in conditioned media from OA chondrocytes or from ATDC5 cells transfected with a gal-3-expressing vector. After generating an OA model by intra-articular injection of 0.5% mono-iodoacetate (MIA), histological evaluation of articular cartilage and subchondral bone was performed in wild-type (WT) and gal-3 knockout (KO) mice aged 6 weeks and 4 months. RESULTS: In vitro experiments demonstrated that intracellular gal-3 had a protective role in chondrocyte survival, which involved its phosphorylation. In contrast to 6-week-old mice, 4-month-old gal-3 KO mice, compared with WT mice, presented OA-like cartilage modifications. OA induction via MIA injection in WT mice generated cartilage lesions similar to those found in gal-3 KO animals. Moreover, OA induction showed a significant decrease in subchondral bone surface in the gal-3 KO mice in contrast to the WT group. CONCLUSIONS: Altogether these findings indicate that intracellular gal-3 has a beneficial effect in articular cells, as its absence in KO mice led to cartilage lesions.

The new collagenase, collagenase-3, is expressed and synthesized by human chondrocytes but not by synoviocytes. A role in osteoarthritis.

Recently, a new human collagenase, collagenase-3 has been identified. Since collagen changes are of particular importance in cartilage degeneration, we investigated if collagenase-3 plays a role in osteoarthritis (OA). Reverse transcriptase-PCR analysis revealed that in articular tissues collagenase-3 was expressed by the chondrocytes but not by the synoviocytes. Northern blot analysis of the chondrocyte mRNA revealed the presence of two major gene transcripts of 3.0 and 2.5 kb, and a third one of 2.2 kb was occasionally present. Compared to normal, OA showed a significantly higher (3.0 kb, P < or = 0.05; 2.5 kb, P < or = 0.03) level of collagenase-3 mRNA expression. Collagenase-3 had a higher catalytic velocity tate (about fivefold) than collagenase-1 on type II collagen. With the use of two specific antibodies, we showed that human chondrocytes had the ability to produce collagenase-3 as a proenzyme and as a glycosylated doublet. The chondrocyte collagenase-3 protein is produced in a significantly higher (P < or = 0.04) level in OA (approximately 9.5-fold) than in normal. The synthesis and expression of this new collagenase could also be modulated by two proinflammatory cytokines, IL-1 beta and TNF-alpha, in a time- and dose-dependent manner. This study provides novel and interesting data on collagenase-3 expression and synthesis in human cartilage cells and suggest its involvement in human OA cartilage patho-physiology.

Elevated hepatocyte growth factor levels in osteoarthritis osteoblasts contribute to their altered response to bone morphogenetic protein-2 and reduced mineralization capacity.

PURPOSE: Clinical and in vitro studies suggest that subchondral bone sclerosis due to abnormal osteoblasts is involved in the progression of osteoarthritis (OA). Human osteoblasts isolated from sclerotic subchondral OA bone tissue show an altered phenotype, a decreased canonical Wnt/ß-catenin pathway, and a reduced mineralization in vitro as well as in vivo. These alterations were linked with an abnormal response to BMP-2. OA osteoblasts release factors such as the hepatocyte growth factor (HGF) that contribute to cartilage loss whereas chondrocytes do not express HGF. HGF can stimulate BMP-2 expression in human osteoblasts, however, the role of HGF and its effect in OA osteoblasts remains unknown. Here we investigated whether elevated endogenous HGF levels in OA osteoblasts are responsible for their altered response to BMP-2. METHODS: We prepared primary human subchondral osteoblasts using the sclerotic medial portion of the tibial plateaus of OA patients undergoing total knee arthroplasty, or from tibial plateaus of normal individuals obtained at autopsy. The expression of HGF was evaluated by qRT-PCR and the protein production by western blot analysis. HGF expression was reduced with siRNA technique whereas its activity was inhibited using the selective inhibitor PHA665752. Alkaline phosphatase activity (ALPase) and osteocalcin release were measured by substrate hydrolysis and EIA respectively. Canonical Wnt/ß-catenin signaling (cWnt) was evaluated both by target gene expression using the TOPflash TCF/lef luciferase reporter assay and western blot analysis of ß-catenin levels in response to Wnt3a stimulation. Mineralization in response to BMP-2 was evaluated by alizarin red staining. RESULTS: The expression of HGF was increased in OA osteoblasts compared to normal osteoblasts and was maintained during their in vitro differentiation. OA osteoblasts released more HGF than normal osteoblasts as assessed by western blot analysis. HGF stimulated the expression of TGF-ß1. BMP-2 dose-dependently (1 to 100 ng/ml) stimulated both ALPase and osteocalcin in normal osteoblasts whereas, it inhibited them in OA osteoblasts. HGF-siRNA treatments reversed this response in OA osteoblasts and restored the BMP-2 response. cWnt is reduced in OA osteoblasts compared to normal, and HGF-siRNA treatments increased cWnt in OA osteoblasts almost to normal. Smad1/5/8 phosphorylation in response to BMP-2, which is reduced in OA osteoblasts, was corrected when these cells were treated with PHA665752. The BMP-2-dependent mineralization of OA osteoblasts, which is also reduced compared to normal, was only partially restored by PHA665752 treatment whereas 28 days treatment with HGF reduced the mineralization of normal osteoblasts. CONCLUSION: OA osteoblasts expressed more HGF than normal osteoblasts. Increased endogenous HGF production in OA osteoblasts stimulated the expression of TGF-ß1 and reduced their response to BMP-2. Inhibiting HGF expression or HGF signaling restored the response to BMP-2 and Smad1/5/8 signaling. In addition, decreased HGF signaling partly corrects the abnormal mineralization of OA osteoblasts while increased HGF prevents the normal mineralization of normal osteoblasts. In summary, we hypothesize that sustained elevated HGF levels in OA osteoblasts drive their abnormal phenotype and is implicated in OA pathophysiology.

The presence of cytoplasmic antineutrophil cytoplasmic antibodies (C-ANCA) in the course of subacute bacterial endocarditis with glomerular involvement, coincidence or association?

Antineutrophil cytoplasmic antibodies positivity with cytoplasmic pattern (C-ANCA) and proteinase-3 (PR-3) specificity was found in two patients with both subacute bacterial endocarditis (SBE) and glomerular involvement. Renal biopsy showed membranoproliferative glomerulonephritis in one case and focal segmental glomerulonephritis in the second case. Immunofluorescence study showed granular immune deposits in both cases evocating immune complex glomerulonephritis. Renal and biological manifestations disappeared with clinical improvement secondary to antibiotherapy. Physicians have to consider the possible occurrence of such C-PR-3 ANCA, claimed to be specific markers for Wegener's granulomatosis, in infectious diseases such as SBE. Hence we focus on the necessity of performing a renal biopsy with light microscopy and immunofluorescence studies in all patients with ANCA associated glomerular disease.

Phospholipase A2 activity in herniated lumbar discs. Clinical correlations and inhibition by piroxicam.

STUDY DESIGN: Prospective study of phospholipase A2 activity in the serum and intervertebral discs of patients undergoing surgery for sciatica due to disc herniation. OBJECTIVES: To determine correlations between herniated disc phospholipase A2 and clinical, radiographic, and anatomic signs of common sciatica; to evaluate serum phospholipase A2 activity as a marker of disc phospholipase A2; and to investigate the in vivo effect of piroxicam on disc phospholipase A2. SUMMARY OF BACKGROUND DATA: Several studies suggest disc inflammation as a mechanism of sciatica due to disc herniation, and phospholipase A2 emerges as a key enzyme of cartilage and disc tissues. METHODS: Phospholipase A2 activity was determined, using the degradation of a specific substrate, in the serum and discs of 31 patients (14 treated with acetaminophen and 17 treated with piroxicam) undergoing surgery for sciatica due to lumbar disc herniation. Visual analog scale for pain, Dallas Pain Questionnaire, Lasègue's sign, radiographic stage of degeneration of the herniated disc, volume of disc herniation shown by computed tomography, and surgical findings were recorded. RESULTS: Disc phospholipase A2 activity was independent of the patient's age or sex, the radiologic stage of disc degeneration, and the volume of the herniation, and showed no significant correlation with Lasègue's sign or pain measured on a visual analog scale. The correlation between disc phospholipase A2 and the Dallas category of items measuring the impact of pain on daily activities approached the level of significance (P = 0.07). Disc phospholipase A2 activity was significantly higher in cases of sequestrated discs than in other herniations. Disc phospholipase A2 was significantly correlated with serum phospholipase A2, and was significantly lower in patients treated with piroxicam than in those treated with acetaminophen. CONCLUSIONS: Disc phospholipase A2 is thought to participate in the physiopathology of sciatica and to bemodulated by nonsteroidal anti-inflammatory drug therapy. Serum phospholipase A2 is suggested as a biologic marker of disc inflammation in patients with sciatica.

[Role of nocturnal hypertension in the deterioration of diabetic nephropathy]. / Rôle de l'hypertension artérielle nocturne dans l'aggravation de la néphropathie diabétique.

UNLABELLED: Nocturnal hypertension (HTA), even a relative one, consequence of the change of the circadian pattern of blood pressure, may increase the whole day blood pressure in diabetic patients. MATERIALS AND METHODS: blood pressure has been measured every 15 minutes for 24 hours in 101 diabetic patients (43 insulin-dependent: type 1, 58 non insulin-dependent: type 2) by ambulatory blood pressure monitoring. 39 of them are hypertensive patients. Among these 101 patients, 19 have a nocturnal relative HTA corresponding in a lack or a negative difference between the diurn and the nocturn systolic or diastolic pressure (Group 1). The Group 2 is constituted by the 82 other patients; 24 hour-microalbuminuria was assayed by immunoturbidimetry for two days on end. RESULTS: patients of Group 1 were significantly older (p less than 0.01) than in the Group 2 (61 +/- 9 years vs 54 +/- 13 years). There was no significant change between the two Groups concerning the kind of diabetes (type 1 or type 2), the glycosylated hemoglobin and the frequency of degenerative complications. Microalbuminuria was significantly higher (p less than 0.01) in Group 1 (72 +/- 104 mg/24 h) than in Group 2 (20 +/- 30 mg/24 h). Both nervous dysautonomic cardiac failure and HTA treated were significantly higher in Group 1 than in Group 2, respectively (14/19 vs 28/82; p less than 0.01) and (15/19 vs 24/82; p less than 0.001). The causal blood pressure measurement was similar in the two Groups, but the whole day ambulatory blood pressure monitoring revealed a significant increase of the average of systolic (Group 1: 133 +/- 14 mmHg vs Group 2: 119 +/- 12 mmHg; p less than 0.001) and diastolic (Group 1: 81 +/- 12 mmHg vs Group 2: 75 +/- 8 mmHg; p less than 0.01) blood pressure during 24 hours. COMMENTS: the causal blood pressure measurement fails to appreciate the increase of the whole day blood pressure consequent to the suppression of nocturnal hypotension and sometimes to the occurrence of real nocturnal hypertension. This observation is probably in relation with the nervous dysautonomic cardiac failure and is associated with an increase of the microalbuminuria (patients with microalbuminuria greater than 30 mg/24 h--Group 1: 9/19 vs Group 2: 17/82; p less than 0.05). This situation can lead to an aggravation of degenerative complications. Such results should urge practitioners to assess the circadian pattern of blood pressure in diabetic patients more accurately.

[Citalopram. An open study of a highly selective serotonin-uptake inhibitor administered by infusion to depressive patients]. / Citalopram. Etude ouverte d'un inhibiteur très sélectif du captage de la sérotonine, administré en perfusion à des patients déprimés.

In an open, clinical trial comprising a total of 49 depressed in-patients, a new selective 5-HT uptake inhibitor citalopram was administered by intravenous infusion in doses of 20-60 mg once daily for per 3 weeks. The therapeutic effect was assessed globally and by means of the CPRS subscale for depression (MADRS). About 40 per cent of the patients showed a complete response whereas about 25 per cent showed a partial response. Side effects which were rated globally and recorded according to a check-list were generally mild and infrequent. The side-effects most frequently observed were tremor, drowsiness, and dizziness which occurred in about 15 per cent of the patients.' Three patients were withdrawn prematurely because of nausea and one because of a skin rash. Cardiovascular recordings were normal except for one patient, who developed a hypertension which may have been related to the test drug. No pathological laboratory values were detected during the trial period. The authors conclude that intravenously administered citalopram is well suited for the treatment of depressed patients.

[Adrenal enzymatic block with late-onset caused by 11-hydroxylase deficiency. Apropos of 29 cases]. / Blocs enzymatiques surrénaliens à révélation tardive par déficit de la 11-hydroxylase. A propos de 29 observations.

Late-onset congenital adrenal hyperplasia is a cause of a spectrum of clinical manifestations of postnatal androgen excess. In these cases, ACTH stimulation test with measurement of 17-Hydroxyprogesterone (17OHP) is usually done to assess 21-hydroxylase (21-OH) deficiency. Determination of the 11-deoxycortisol (S) and the S to cortisol ratio is rarely done, so that 11 beta-hydroxylase (11-OH) deficiency seems unusual. We systematically investigated this biosynthetic defect among women complaining of hyperandrogenism (n = 519) and, comparing the patient's hormonal responses to ACTH with those of 31 normal women, found 29 11-OH deficiency (5.6%): this is the largest group ever reported. S was elevated only 9 times, so that using this single determination, diagnosis of 20 enzymatic defects would not have been made. Only three of the patients (10%) had hypertension, even though the pathway of aldosterone was involved in 33% of cases (criteria: elevation of the ratio desoxycorticosterone to corticosterone). We also described one new patient with both 11-OH and 3-beta-hydroxysteroid dehydrogenase deficiencies. The patho-physiology is particularly interesting in these cases. It is concluded that the single research for 21-OH deficiency is inadequate among women complaining of hyperandrogenism: the screening for 11-OH deficiency should be made, even if blood pressure is normal.

[Hormonal profile of idiopathic gynecomastia in young adults. Apropos of 488 cases]. / Profil hormonal des gynécomasties idiopathiques de l'adulte jeune. A propos de 488 cas.

Gynecomastia, a very frequent disorder, is present in almost 40% of young men. In this population the investigations often fail to find any aetiology, therefore defining idiopathic gynecomastia. The aim of this work is to compare clinical and hormonal characteristics of 488 subjects with gynecomastia to 41 healthy controls. Their are many explanations for the occurrence of idiopathic gynecomastia, including modification of hormonal balance, change of aromatase activity, or a receptor anomaly. Our works demonstrate a significant decrease in mean testosteronemia, linked to a high prevalence of incipient hypogonadism in the studied population, especially in patients with an history of testicular disease.

Oxidative stress-induced expression of HSP70 contributes to the inhibitory effect of 15d-PGJ2 on inducible prostaglandin pathway in chondrocytes.

The inhibitory effect of 15-deoxy-Δ(12,14)-prostaglandin J2 (15d-PGJ2) on proinflammatory gene expression has been extensively documented and frequently ascribed to its ability to prevent NF-κB pathway activation. We and others have previously demonstrated that it was frequently independent of the peroxisome proliferator activated receptor (PPAR)γ activation. Here, we provide evidence that induction of intracellular heat shock protein (HSP)70 by oxidative stress is an additional regulatory loop supporting the anti-inflammatory effect of 15d-PGJ2 in chondrocytes. Using real-time quantitative PCR and Western blotting, we showed that 15d-PGJ2 stimulated HSP70, but not HSP27 expression while increasing oxidative stress as measured by spectrofluorimetry and confocal spectral imaging. Using N-acetylcysteine (NAC) as an antioxidant, we demonstrated further that oxidative stress was thoroughly responsible for the increased expression of HSP70. Finally, using an HSP70 antisense strategy, we showed that the inhibitory effect of 15d-PGJ2 on IL-1-induced activation of the NF-κB pathway, COX-2 and mPGES-1 expression, and PGE2 synthesis was partly supported by HSP70. These data provide a new anti-inflammatory mechanism to support the PPARγ-independent effect of 15d-PGJ2 in chondrocyte and suggest a possible feedback regulatory loop between oxidative stress and inflammation via intracellular HSP70 up-regulation. This cross talk is consistent with 15d-PGJ2 as a putative negative regulator of the inflammatory reaction.

Identification of opticin, a member of the small leucine-rich repeat proteoglycan family, in human articular tissues: a novel target for MMP-13 in osteoarthritis.

OBJECTIVE: One of the proteoglycan families is the small leucine-rich proteoglycans (SLRPs) that are characterized by their association with collagen fibrils and/or some glycosaminoglycans. Opticin is a glycoprotein and class III member of the SLRP family, which was initially identified in the vitreous humour of the eye. In this study, we first investigated whether opticin is expressed and produced in normal and OA human articular tissues/cells. Further, we investigated the ability of the key metalloprotease involved in cartilage pathology, MMP-13, to cleave human cartilage opticin. METHODS: Opticin gene expression was investigated in normal and OA human chondrocytes, synovial fibroblasts, and subchondral bone osteoblasts by reverse transcriptase-polymerase chain reaction (RT-PCR). Opticin protein production was determined in normal and OA synovial membrane and cartilage by immunohistochemistry. Opticin was isolated from human cartilage using guanidinium chloride extraction, and human MMP-13-induced opticin degradation analyzed by Western blotting. Finally, the opticin MMP-13 cleavage site was determined. RESULTS: Opticin was expressed in human chondrocytes, synovial fibroblasts and subchondral osteoblasts, and the protein identified in synovial membrane and cartilage. At the protein level, OA cartilage showed a slightly higher level of opticin positive stained chondrocytes than normal cartilage; this did not reach statistical significance. However, in contrast with OA, normal cartilage demonstrated a high level of matrix staining in the superficial zone of the tissue, suggesting that in the OA cartilage matrix, opticin is degraded. Data also showed that cartilage opticin could be cleaved by MMP-13 after only 2h of incubation, indicating a preferential substrate compared to other SLRPs for this enzyme. Microsequencing revealed a major cleavage site at the G(104)/L(105)LAAP and a minor at P(109)/A(110)NHPG upon MMP-13 exposure. CONCLUSION: We demonstrated, for the first time, that opticin is expressed and produced in human articular tissues. Our data also showed that opticin in OA cartilage is degraded in a process that could be mediated by MMP-13. As opticin may contribute towards the structural stability of cartilage, its cleavage by MMP-13 may predispose cartilage to degeneration, particularly at the surface.

Subchondral and trabecular bone metabolism regulation in canine experimental knee osteoarthritis.

OBJECTIVE: To determine trabecular and subchondral bone metabolic changes in experimental canine osteoarthritis (OA). METHODS: OA was induced in 19 dogs by transection of the anterior cruciate ligament (ACL) of the right knee through a stab wound. Dogs were sacrificed at 8 (n=7) and 12 weeks (n=12) after surgery. Non-operated normal dogs (n=6) were used as controls. After sacrifice, samples were obtained from the weight-bearing area of medial tibial plateaus. Explants and cell cultures were prepared from subchondral and trabecular bone. Osteocalcin (Oc), cellular alkaline phosphatase (ALPase), urokinase plasminogen-activator (uPA), prostaglandin E2 (PGE2), metalloproteinase (MMP) and nitric oxide (NO) were measured using standard procedures. RESULTS: ALPase production was significantly increased only at week 12 in subchondral and trabecular bone, while an increase in Oc was noted at week 8. uPA and MMP activity were increased significantly at week 12 in subchondral bone, while PGE2 levels were significantly higher in subchondral and trabecular bone at week 12 compared to normal. A decrease in NO production appeared late at week 12 in trabecular bone, whereas NO levels from subchondral bone were significantly increased compared to normal at week 8. DISCUSSION: Intense bone remodeling takes place in both subchondral and trabecular bone in the knee following ACL transection. This process seems to occur around week 12, although Oc and NO appeared to be involved earlier at 8 weeks. These results suggest that not only subchondral but also trabecular bone metabolism is altered in this OA model.

Study of retinoic acid effect upon retinoic acid receptors beta (RAR-beta) in C6 cultured glioma cells.

Using monoclonal antibodies against the RAR-alpha and RAR-beta retinoic receptors, we demonstrated that these receptors were present together in C6 glioma cells as two isoforms of 50 and 55 kDa. For RAR-beta, the 50 kDa isoform predominated (60 to 80% of the total of the two isoforms). After a treatment for 48 h with retinoic acid 10 microM, the 55 kDa form was enhanced, while no effect was observed either on RAR-alpha isoforms from C6 cells and on both RAR-alpha and RAR-beta forms from neuroblastoma SKN SH SY5Y used as a control. Using purified neuronal and glial rat brain nuclei, we showed that the 55 kDa isoform from RAR-beta predominated in glial cells. These results suggest that retinoic acid treatment of C6 cells led to a partial differentiation, the enhancement of the heavy form of RAR-beta being a marker of this phenomenon.

Effect of retinoic acid on two glycosyltransferase activities in C6 cultured glioma cells.

1. Activity of two glycosyltransferases was studied in retinoic acid-treated C6 cultured glioma cells. 2. The beta-galactoside alpha 2,3-sialyltransferase transferring N-acetylneuramin onto the O-glycans residues of glycoproteins was activated up to twice after chronic treatment (from 24 to 96 hr) with all-trans retinoic acid. 3. No effect was observed for shorter treatments. 4. On the opposite, the N-glycan galactosyltransferase activity remained unchanged whatever the length of retinoic acid treatment was. 5. The activatory effect was not dependent on isomery, as all-trans and 13-cis retinoic acid isomers were both activators of the C6 glioma cell sialyltransferase. 6. Measurement of adhesion of retinoic acid-treated cells using labelled plasma membranes showed an enhancement of adhesion in correlation with enhancement of sialyltransferase activity.

[Critical study of the characterization of hyperandrogenism in a group of obese women]. / Etude critique de la caractérisation de l'hyperandrogénie dans un groupe de femmes obèses.

The authors report the hormonologic characteristics of 20 obese and hirsute women meeting the criteria for adrenaltype hyperandrogenism, suppressible by dexamethasone, without hyperprolactinemia and without any late developing partial enzyme block appearance. The laboratory profile of these women differed from that of a group of women with type 1 polycystic ovaries syndrome. In this same group obese women in whom LH/FSH ratio was below 1, there was evidence under baseline conditions of a moderate increase in testosterone and delta 4-androstenedione in relation to increased plasma levels of DHA and SDHA, plasma delta 4 and delta 5-androgen levels falling precipitalely during the dexamethasone suppression test. The ACTH stimulation test revealed greater reactivity for 17 hydroxy-pregnenolone (p < 0.001) and less for 21-deoxycortisol than in the control group of normal women (p < 0.01). The essentially adrenal origin of plasma hyperandrogenism in certain cases of obesity is discussed. Insulin could increase adrenal sensitivity to ACTH and its possible action in vivo on the activity of adrenal enzymes requires clarification. The accumulation of certain androgens in the adrenal cortex could also be responsible for dysregulation of 3 beta ol-dehydrogenase and 11-hydroxylase.

Study of O-glycan sialylation in C6 cultured glioma cells: evidence for post-translational regulation of a beta-galactoside alpha 2,3 sialyltransferase activity by N-glycosylation.

We have studied the Gal beta 1-3GalNAc-R alpha 2,3 sialyltransferase from C6 glioma cells transferring Neu5Ac from CMP-Neu5Ac onto O-glycans of glycoproteins. Using synchronized C6 glioma cells, we showed that the alpha 2,3 sialyltransferase activity was inhibited by tunicamycin to a greater extend than DNA and protein biosynthesis suggesting inhibition of N-glycosylation of this enzyme. Additional demonstration of N-glycosylation of the alpha 2,3 sialytransferase was provided through ConA-Sepharose binding. Treatment of partially purified alpha 2,3 sialytransferase by peptide-N-glycosidase F showed a significative inhibition demonstrating that N-glycan moiety is required for complete activity of the C6 glioma cell alpha 2,3 sialyltransferase.