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J C Fernandes

Publications and source records attributed to J C Fernandes.

At least 19 recordsLinked to original sources
PubMed2002

Peroxisome proliferator-activated receptor gamma activators inhibit MMP-1 production in human synovial fibroblasts likely by reducing the binding of the activator protein 1.

OBJECTIVE: To investigate the expression and activity of PPARgamma in human synovial fibroblasts and the effects of PPARgamma agonists on the expression of MMP-1. The molecular mechanisms by which PPARgamma agonists modulate MMP-1 expression were also examined. METHODS: PPARgamma expression and activity were measured using reverse-transcription polymerase chain reaction (RT-PCR) and transient transfection assays. Human synovial fibroblasts were cultured with IL-1beta in the absence or presence of PPARgamma activators, and the expression and production of MMP-1 were evaluated by Northern blot and ELISA, respectively. The effect of 15d-PGJ(2) on MMP-1 promoter activation was analysed in transient transfection experiments, while electrophoretic mobility shift assays were performed to study the binding activity of the transcription factor AP-1. RESULTS: PPARgamma was expressed and transcriptionally functional in human synovial fibroblasts. PPARgamma activators (15d-PGJ(2) and BRL 49653) inhibited IL-1beta-induced MMP-1 synthesis in a dose-dependent manner. Similarly, both activators inhibited IL-1-induced MMP-1 mRNA expression. Activation of the human MMP-1 promoter was also attenuated by 15d-PGJ(2), indicating that the inhibitory effect of 15d-PGJ(2) occurs at the transcriptional level. Interestingly, 15d-PGJ(2) reduced both basal and IL-1beta-induced AP-1 binding activity. CONCLUSIONS: These data indicate that PPARgamma agonists inhibit MMP-1 gene expression by transcriptional mechanisms, and suggest that they may be useful in reducing joint tissue destruction.

Aged↗
PubMed2001

Structural transition and pair formation in Fe3O2BO3.

We observe for the first time a structural phase transition in the oxyborate Fe3O2BO3 which occurs along three leg ladders present in this material. X-ray diffraction shows that this transition at 283 K is associated with a new phase where atomic displacements occur in alternate directions perpendicular to the axis and within the plane of the ladders. Magnetic data show that these displacements lead to the formation of singlet pairs which dissociate close to the structural transition. Anomalies in the transport properties also occur close to 283 K showing that the structural transition is related to a charge ordering phenomenon in a low dimensional structure.

Journal Article↗
PubMed2001

In vivo dual inhibition of cyclooxygenase and lipoxygenase by ML-3000 reduces the progression of experimental osteoarthritis: suppression of collagenase 1 and interleukin-1beta synthesis.

OBJECTIVE: To study the therapeutic effectiveness of ML-3000, a new antiinflammatory drug that has balanced dual inhibitory activity against 5-lipoxygenase and cyclooxygenase, on the development of lesions in the experimental osteoarthritis (OA) dog model, and to determine the action of ML-3000 on the synthesis of collagenase 1 in cartilage and interleukin-1beta (IL-1beta) in synovial membrane. METHODS: The anterior cruciate ligament of the right stifle joint of 21 mongrel dogs was sectioned with a stab wound. Dogs were divided into 3 groups: group 1 (n = 7) received placebo; groups 2 (n = 7) and 3 (n = 7) were treated with therapeutic dosages of oral ML-3000 at 2.5 mg/kg/day and 5 mg/kg/day, respectively. The dogs began receiving medication the day after surgery and were killed 8 weeks later. The size and grade of cartilage erosions on both the condyles and plateaus were evaluated, and the severity of the cartilage lesions and synovial inflammation was examined histologically. Levels of collagenase 1 in cartilage and IL-1beta in the synovial membrane were measured by immunohistochemistry. In addition, levels of prostaglandin E2 (PGE2) in the synovial fluid and leukotriene B4 (LTB4) in cultured synovial membrane explants were determined using specific enzyme immunoassays. RESULTS: Serum levels of ML-3000 in treated dogs were within the therapeutic range. ML-3000 significantly decreased the size and grade of the cartilage lesions in tibials and plateaus, compared with placebo. At the histologic level, the severity of cartilage lesions was also decreased in the ML-3000-treated dogs versus the placebo-treated dogs in both the condyles and the plateaus. All 3 OA groups exhibited a notable and similar level of synovial inflammation. ML-3000 significantly decreased the level of PGE2 in synovial fluid and LTB4 production by synovium. It also markedly reduced the levels of collagenase 1 in cartilage and IL-1beta in synovial membrane. CONCLUSION: ML-3000 significantly reduced the development of lesions in experimental dog OA. The drug acts by reducing the synthesis of the inflammation mediators PGE2 and LTB4 and catabolic factors such as collagenase 1 and IL-1beta, which are known to play an important role in the pathophysiology of OA lesions. The effect of the drug on catabolic factors could possibly be related to its inhibitory action on LTB4 synthesis.

Acetates↗
PubMed2001

Endogenous prostaglandin E2 and insulin-like growth factor 1 can modulate the levels of parathyroid hormone receptor in human osteoarthritic osteoblasts.

Subchondral bone sclerosis may be important for the onset and/or progression of cartilage loss/damage in human osteoarthritis (OA). OA osteoblasts are resistant to parathyroid hormone (PTH) stimulation, which could explain bone sclerosis via the inhibition of PTH-dependent catabolism. Here, we investigated the molecular mechanism(s) responsible for reduced PTH-dependent cyclic adenosine monophosphate (cAMP) synthesis in OA subchondral osteoblasts. Although cholera toxin (CTX) increased basal cAMP formation in these cells, it failed to stimulate PTH-dependent cAMP synthesis, whereas pertussis toxin (PTX) did not inhibit basal cAMP, yet diminished PTH-dependent cAMP production. Binding of 125I-PTH indicated lower PTH receptor levels in OA than in normal osteoblasts (-50.5 +/- 9.5%). This could be attributed to either reduced expression of the PTH receptor (PTH-R) or altered recycling of existing pools of receptors. Reverse-transcription polymerase chain reaction (RT-PCR) analysis indicated decreased PTH-R messenger RNA (mRNA) levels in OA cells that were highly variable (ranging from -10% to -60%), a situation that reflects disease severity. Interestingly, OA osteoblasts produced more prostaglandin E2 (PGE2) than normal osteoblasts, and using naproxen, a cyclo-oxygenase inhibitor, increased PTH-dependent cAMP formation to a level similar to normal osteoblasts. Because heterologous desensitization can explain a decrease in PTH binding but cannot account for reduced PTH-R expression, we looked at the possible effect of insulin-like growth factor 1 (IGF-1) on this parameter. Blocking IGF-1 signaling with a neutralizing receptor antibody increased 125I-PTH binding in both normal and OA osteoblasts. Conversely, treatments with IGF-1 receptor (IGF-1R) antibody only slightly increased the levels of PTH-R mRNA whereas the addition of IGF-1 significantly reduced PTH-R mRNA levels (-24.1 +/- 7.1%), yet neither PGE2 nor naproxen modified PTH-R levels. These results suggest that both IGF-1 signaling and PGE2 formation repress PTH-dependent response in OA osteoblasts, a situation that can contribute to abnormal bone remodeling and bone sclerosis in OA.

Aged↗
PubMed2001

Tufted hair folliculitis after scalp injury.

We describe the case of a 38-year-old epileptic man with tufted hair folliculitis. The condition started 5 years ago after a scalp laceration that had been sustained 3 months earlier during an epileptic crisis. There then appeared a circumscribed inflammatory bulging lesion (with exudation and crusts) that evolved to scarring alopecia with tufts of 20 to 30 apparently normal hair shafts. Results of bacteriologic examination of pus extruding from the dilated follicular ostia revealed Staphylococcus aureus. The cutaneous pathologic examination showed polymorphous inflammatory exudate in the upper and mid dermis, which was mostly perifollicular, and the presence of normal and independent follicles in the deep dermis, which, while ascending, converged to a common dilated follicular channel. The patient was treated successively with oral flucloxacillin, erythromycin, ciprofloxacin, and amoxicillin/clavulanic acid and with topical application of erythromycin, clindamycin, povidone iodine, and ketoconazole. Transient improvement was followed by recurrence and enlargement of the affected area.

Adult↗
PubMed2001

Diacerein reduces the excess synthesis of bone remodeling factors by human osteoblast cells from osteoarthritic subchondral bone.

OBJECTIVE: Although cartilage degradation characterizes osteoarthritis (OA), there is evidence that remodeling of subchondral bone in this disease is a contributing factor. Therapeutic strategies to modify the metabolism of subchondral bone osteoblasts may be indicated to treat OA. We studied the effects of diacerein and rhein on the metabolic and inflammatory variables of OA subchondral osteoblasts. METHODS: Human OA primary subchondral osteoblast cells were used. The effect of diacerein and rhein at therapeutic concentrations (5-20 microg/ml) was determined by osteoblast phenotypic factors, alkaline phosphatase, osteocalcin, and cAMP; on metabolic agents urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), and insulin-like growth factor-1 (IGF-1); and on inflammatory mediators interleukin 6 (IL-6), prostaglandin E2 (PGE2), and cyclooxygenase-2 (COX-2). RESULTS: Diacerein and rhein did not affect either basal and 1,25(OH)2D3 induced alkaline phosphatase or parathyroid hormone (PTH) stimulated cAMP formation. Conversely, they dose dependently and statistically inhibited 1,25(OH)2D3 induced osteocalcin release, a situation explained by a reduction of mRNA levels for osteocalcin. Of the metabolic factors, they inhibited the production of uPA, with rhein showing slightly more potency; inhibitions of 69% and 57% were reached at the highest concentration (20 microg/ml) of rhein and diacerein, respectively. Both drugs also inhibited the PAI-1 level, albeit at a much lower level than for uPA. Interestingly, determination of the uPA/PAI1 ratio revealed that both drugs inhibited it about 55%, suggesting a decrease in uPA activity. In contrast, IGF-1 levels only increased slightly when cells were treated with rhein but not with diacerein. A transient dose dependent effect was found on IL-6 production; an inhibition was noted at low drug concentrations, which returned to basal levels at the highest concentration tested. PGE2 levels increased exponentially and were related to a concomitant increase in COX-2 levels in response to both drugs. CONCLUSION: Our data indicate that diacerein and rhein do not appear to affect OA subchondral bone cells' basal cellular metabolism, yet both agents reveal a direct effect at reducing the synthetic activities of osteoblasts, which could be responsible for abnormal subchondral bone remodeling occurring during the course of OA.

Aged↗
PubMed2001

Chondrocyte death in experimental osteoarthritis is mediated by MEK 1/2 and p38 pathways: role of cyclooxygenase-2 and inducible nitric oxide synthase.

OBJECTIVE: To explore the mechanisms responsible for in situ induction of chondrocyte death in experimental dog osteoarthritic (OA) cartilage. The roles of 2 mitogen activated protein kinases (MAPK), MEK 1/2 and p38, nuclear factor-kappaB (NF-kappaB), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and the caspase cascade were investigated. METHODS: OA knee cartilage was obtained from dogs that had received sectioning of the anterior cruciate ligament and were sacrificed 12 weeks after surgery. Cartilage explants were cultured in different inhibitors: Z-DEVD-FMK (caspase 3 inhibitor), Z-LEHD-FMK (caspase 9 inhibitor), PD 98059 (MEK 1/2 inhibitor). SB 202190 (p38 inhibitor), SN-50 (NF-kappaB inhibitor), NS-398 (COX-2 inhibitor), N-iminoethyl-l-lysine (L-NIL) (iNOS inhibitor). Cartilage specimens were stained for TUNEL reaction and immunostained using specific antibodies for caspase 3, COX-2, iNOS, and nitrotyrosine. Morphometric analyses were performed. RESULTS: The significant level of chondrocyte death in OA cartilage was markedly decreased by caspase 3 and caspase 9 inhibitors. The two MAPK inhibitors, but not the NF-kappaB inhibitor, decreased chondrocyte death concomitant with the levels of caspase 3 and iNOS. COX-2 level was reduced by all 3 inhibitors. Specific inhibition of either COX-2 or iNOS reduced the level of chondrocyte death and caspase 3. There was evidence of crosstalk between these 2 latter systems; specific inhibition of COX-2 reduced the iNOS level, and selective inhibition of iNOS reduced COX-2 expression. COX-2 and iNOS seem to function in a positive autoregulatory manner that triggers transcription of their own biosynthetic machinery, since the specific inhibition of each system downregulates its expression. CONCLUSION: This study shows that in the early lesions of experimental OA cartilage in situ, activation of the caspase cascade is responsible for induction of chondrocyte death. Marked inhibition of cell death by caspase inhibitors indicates a significant participation of apoptosis in the phenomenon. This phenomenon is linked to the activation of at least 2 major kinase pathways, MEK 1/2 and p38. These pathways are responsible for upregulating the expression of iNOS and COX-2, each of which seems essential for the induction of apoptosis. Data are provided about possible regulation and interregulation of the COX-2 and iNOS systems by prostaglandin E2 and NO.

Animals↗
PubMed2000

Selective inhibition of inducible nitric oxide synthase reduces progression of experimental osteoarthritis in vivo: possible link with the reduction in chondrocyte apoptosis and caspase 3 level.

OBJECTIVE: To evaluate the in vivo therapeutic efficacy of N-iminoethyl-L-lysine (L-NIL), a selective inhibitor of inducible nitric oxide synthase, on the progression of structural lesions in the experimental canine model of osteoarthritis (OA), and to explore the effect of L-NIL on the level of chondrocyte apoptosis and of important proteins involved in the apoptotic phenomenon, i.e., caspase 3 (inducer) and Bcl-2 (inhibitor). METHODS: The OA model was created by sectioning the anterior cruciate ligament. Dogs were placed into 4 experimental groups: unoperated dogs that received no treatment (controls), operated (OA) dogs that received placebo treatment, OA dogs that received oral L-NIL at 10 mg/kg/day, and OA dogs that received oral L-NIL at 1.0 mg/kg/day. In both L-NIL groups, treatment started immediately after surgery. The OA dogs were killed at 12 weeks after surgery. RESULTS: OA dogs treated with L-NIL showed a reduction in the size of osteophytes and a significant decrease in the severity of macroscopic and histologic cartilage lesions on both condyles and plateaus, compared with untreated OA dogs. L-NIL treatment also significantly decreased metalloprotease activity in cartilage. Immunohistochemical analysis revealed that the levels of chondrocyte apoptosis, caspase 3, and Bcl-2 were markedly increased in OA cartilage (P < 0.0001). A positive correlation between the levels of chondrocyte apoptosis and levels of caspase 3 was found (r = 0.54, P < 0.0001). OA dogs treated with the higher dosage L-NIL showed significantly reduced levels of chondrocyte apoptosis (P < 0.003) and caspase 3 (P < 0.04), but no effect on the increased level of Bcl-2 was demonstrated. CONCLUSION: This study shows that L-NIL reduces the progression of experimental OA. This effect could be related to a reduced level of chondrocyte apoptosis and is likely mediated by a decrease in the level of caspase 3 activity. A sparing effect of L-NIL on the increased level of Bcl-2 may also be a contributing factor.

Animals↗
PubMed2000

Gene therapy for osteoarthritis: new perspectives for the twenty-first century.

Morphologic changes observed in osteoarthritis include cartilage erosion and a variable degree of synovial inflammation. Proinflammatory cytokines such as interleukin-1 beta, locally produced by the inflamed synovium, also likely contribute to these alterations. Despite an extensive armamentarium and numerous surgical options, osteoarthritis remains incurable, and an improved approach in the treatment of this disease is imperative. Drug delivery is a major weakness of existing antiarthritic therapies. Local delivery of antiinflammatory cytokines or the in vivo induction of their expression using gene transfer may provide a novel approach for the treatment of osteoarthritis. Evidence of the efficacy of gene therapy in osteoarthritis remains very scarce. To the authors' knowledge, there is no clinical research protocol en route for the treatment of osteoarthritis using gene therapy. The authors present the only two studies that have proved successful in treating animal models of osteoarthritis using gene therapy, and propose an overview of several strategies for the development of gene therapy in osteoarthritis treatment in the future.

Animals↗
PubMed2000

Carprofen simultaneously reduces progression of morphological changes in cartilage and subchondral bone in experimental dog osteoarthritis.

OBJECTIVE: To examine the effect of a nonsteroidal antiinflammatory drug, carprofen, on the structure and metabolism of cartilage and subchondral bone in the experimental osteoarthritic (OA) canine model. METHODS: Experimental Groups 1 and 2 received a sectioning of the anterior cruciate ligament (ACL) of the right stifle joint, and were administered carprofen (2.2 and 4.4 mg/kg/twice daily/po, respectively) for 8 weeks beginning 4 weeks postsurgery. Group 3 received ACL sectioning and no treatment. Group 4 was composed of unoperated normal dogs. Cartilage macroscopic lesions were assessed, and their histological severity was graded. Specimens of subchondral bones were fixed, decalcified, and stained with hematoxylin/eosin. The level of metalloprotease (MMP) activity in cartilage was measured. Osteoblast cells were prepared from the subchondral bone. The level of synthesis of osteoblast biomarkers (osteocalcin, alkaline phosphatase), as well as urokinase plasminogen activator (uPA) activity and insulin-like growth factor (IGF-1) in the culture medium, was estimated. RESULTS: Carprofen treatment decreased the width of osteophytes (p < 0.01), the size of cartilage lesions, and the histologic severity of cartilage lesions (p < 0.008). There was no difference in the levels of MMP activity in cartilage between OA and carprofen treated groups. In OA dogs, the subchondral bone plate was thinner and was the site of an extensive remodeling process with numerous lacunae. Dogs treated with carprofen showed a marked decrease in the remodeling activity with normal plate thickness, and subchondral bone morphology resembling that of normal dogs. Osteoblasts from untreated OA dogs showed slightly higher alkaline phosphatase activities and osteocalcin release that reverted back to normal upon carprofen treatment. Moreover, uPA activity and IGF-1 levels were increased in OA dogs and were significantly reduced in carprofen treated dogs. CONCLUSION: Under therapeutic conditions, treatment with carprofen could reduce the progression of early structural changes in experimental OA. Carprofen treatment also delays and/or prevents the abnormal metabolism of subchondral osteoblasts in this model. The hypothesis of a possible link between the protective effect of carprofen and its effect on subchondral bone is of interest in the context of therapeutic intervention.

Alkaline Phosphatase↗
PubMed1999

Pharmacologic therapy of osteoarthritis.

This article presents a brief review of the most current therapies that are used for the relief of the symptoms related to osteoarthritis. The agents used either systematically or locally are described, providing the rationale for their usage in the treatment of osteoarthritis. Moreover, new therapies that have reached clinical evaluations and that can possibly reduce or stop the progression of the disease--namely the inhibitors of metalloproteases--are presented. Overall, it is obvious that significant progress has been made toward the development of new therapeutic agents to reduce the symptoms as well as the structural changes of the disease.

Adrenal Cortex Hormones↗
PubMed1999

Reduction in the structural changes of experimental osteoarthritis by a nitric oxide inhibitor.

OBJECTIVE: To evaluate the in-vivo therapeutic efficacy of N -iminoethyl-L-Lysine (L-NIL), a selective inhibitor of inducible nitric oxide synthase (iNOS) in a dose response study, on the progression of lesions in the experimental osteoarthritic (OA) dog model. DESIGN: The sectioning of the anterior cruciate ligament of the right stifle joint of mongrel dogs was done by a stab wound. Dogs were separated into experimental groups: Group 1 received no treatment, Groups 2, 3, and 4 received oral L-NIL (0.3, 1 or 10mg/kg/day, respectively) starting immediately after surgery. The OA dogs were killed at 12 weeks after surgery. RESULTS: Macroscopically, L-NIL decreased the size of the cartilage lesions on condyles and plateaus. The histologic severity of the cartilage lesions was decreased in the L-NIL-treated dogs. This effect was more pronounced at the highest dosage tested (3 and 10mg/kg/day). CONCLUSIONS: This study confirms the effectiveness of L-NIL, a selective inhibitor of iNOS, in attenuating the progression of experimental OA. It also clearly shows that the effect is dose-dependent.

Animals↗
PubMed1999

Selective inhibition of inducible nitric oxide synthase in experimental osteoarthritis is associated with reduction in tissue levels of catabolic factors.

OBJECTIVE: We used the experimental dog model of osteoarthritis (OA) to examine the in vivo effects of N-iminoethyl-L-lysine (L-NIL), a selective inhibitor of the inducible nitric oxide synthase (iNOS), on the tissue level and distribution of interleukin-1beta (IL-1beta), collagenase-1, stromelysin-1, cyclooxygenase-2 (COX-2), iNOS and nitrotyrosine, through immunohistochemical and morphometric analysis. METHODS: Cartilage and synovial membrane specimens were obtained from 3 experimental groups of dogs: Group I--unoperated dogs that received no treatment; Group II--dogs subjected to a sectioning of the anterior cruciate ligament of the right knee and given no treatment; and Group III--operated dogs that received oral treatment with L-NIL (10 mg/kg twice daily/po) for 10 weeks starting immediately after surgery. The operated dogs were killed 10 weeks post-surgery. The tissue distributions of IL-1beta, metalloproteases (MMP), COX-2, iNOS and nitrotyrosine were documented by immunohistochemistry using specific antibodies, and quantified by morphometric analysis. RESULTS: In cartilage, the cell scores (percentage of chondrocytes staining positive for the antigen) for iNOS and 3-nitrotyrosine were dramatically enhanced in OA specimens compared to normal (p < 0.0001). However, the cartilage of dogs treated with L-NIL showed significantly lower cell scores for iNOS (p<0.0001, condyle; p<0.001, plateau), nitrotyrosine (p<0.0004; p<0.0001) and COX-2 (p<0.0001; p<0.001) compared to that of untreated OA dogs. Similar findings were observed for collagenase-1 and stromelysin-1, where the increased cell scores of these 2 MMP in OA cartilage were reduced after treatment with L-NIL (collagenase: p<0.002, condyle; p<0.0003, plateau; stromelysin: p<0.006; p<0.0001). The increased cell scores for the IL-1beta, COX-2, iNOS and nitrotyrosine found in the synovial lining and mononuclear cell infiltrate of operated animals were also found to be markedly reduced in dogs treated with L-NIL. CONCLUSION: Our study demonstrates for the first time in vivo in an experimental model of OA, that a selective inhibition of iNOS by L-NIL and the subsequent decreased production of NO also results in a marked decrease in production of major catabolic factors such as MMP, IL-1beta and peroxynitrite, as well as a reduction in COX-2 expression.

Animals↗
PubMed1999

[Mechanical evaluation of a ligament fixation system for ACL reconstruction at the tibia in a canine cadaver model].

OBJECT: Excellent fixation of an artificial ligament in bone is mandatory for initial stability. ACL reconstruction with the LARS artificial ligament may fail if anchorage to bone is inadequate. The weak metaphyseal bone of the proximal tibia is prone to inadequate fixation. This study evaluates the initial mechanical stability of two techniques with an interference screw on the tibial side of an ACL reconstruction with the LARS ligament. METHODS: Six left tibias were obtained from 1 to 3 year old mongrel dog weighing 20 to 26 kg. ACL straight line reconstruction according to the technique described by J.P. Laboureau was performed with a 4.5 mm drill. Two tunnels were created in the tibia, one oblique and one transverse, the latter 2 cm below the former. Reconstruction was done with a 30-fiber LARS ligament and a 5.2 mm x 15 mm conical titanium cannulated interference screw. Group I had an interference screw in the oblique tunnel and group II had an interference screw in the transverse tunnel. Pull-out tests were performed parallel to the oblique tunnel on an Instron 8521 machine at a speed of 5 mm per minute until failure. The oblique tunnel was tested first then the transverse tunnel. RESULTS: Group I (n = 6): sliding value = 238 +/- 115 N. Group II (n = 6): sliding value = 998 +/- 148 N. This is statistically significant (p < 0.001, student t-test). CONCLUSION: One interference screw in a transverse tibial tunnel for ACL reconstruction with the LARS ligament is 4 times more resistant on loading and impact than an oblique screw.

Animals↗
PubMed1998

Study of NADH stability using ultraviolet-visible spectrophotometric analysis and factorial design.

The chemical stability of nicotinamide adenine dinucleotide coenzyme (NADH/NAD+) and its derivatives (NADPH/NADP+) was investigated using changes in the UV-visible absorption spectra of these compounds. The spectra of cofactor (reduced form) were monitored at 340 nm wavelength in different buffers, showing a faster degradation in phosphate buffer. This was assigned to the adduct formation between phosphate and NADH (pyridine ring). The three-factor-two-level factorial design study evaluated the contributions: buffers (phosphate and Pipes 0.1 M), pH's (6.8 and 7.8), and temperature (25 and 30 degrees C). The freshly prepared aqueous solutions of coenzyme were analyzed after 40 min under the different conditions (eight assays in triplicate) of the experiment. The main observed effects of the NADH oxidation were, in increasing order, pH, temperature, and buffer without appreciable interactive effects. Therefore, it was verified that the better conditions for cofactor use were alkaline media employing Pipes buffer or its derivatives and low temperatures.

Buffers↗
PubMed1998

Reduced progression of experimental osteoarthritis in vivo by selective inhibition of inducible nitric oxide synthase.

OBJECTIVE: To evaluate the in vivo therapeutic efficacy of N-iminoethyl-L-lysine (L-NIL), a selective inhibitor of inducible nitric oxide synthase (iNOS), on the progression of lesions in an experimental osteoarthritis (OA) dog model. The effect of L-NIL on metalloprotease activity, levels of interleukin-1beta (IL-1beta), prostaglandin E2 (PGE2), and nitrite/nitrate in synovial fluid was determined. METHODS: The OA model was created by sectioning the anterior cruciate ligament of the right stifle joint of mongrel dogs by a stab wound. Dogs were separated into experimental groups: Group 1 was made up of unoperated dogs that received no treatment, group 2 were operated dogs with no treatment, and group 3 were operated dogs that received oral L-NIL (10 mg/kg/twice daily) starting immediately after surgery. The OA dogs were killed at 10 weeks after surgery. RESULTS: Experiments showed that dog OA cartilage explants in culture produced an increased amount of NO (nitrite). Immunohistochemical study demonstrated that this was due to an increased level of iNOS in chondrocytes. OA dogs treated with L-NIL showed a reduction in the incidence of osteophytes compared with the untreated OA dogs (58% versus 92%) as well as in their size (mean +/- SEM 1.92 +/- 0.58 mm versus 5.08 +/- 0.66 mm). Macroscopically, L-NIL decreased the size of the cartilage lesions by approximately 50% both on condyles and plateaus. The histologic severity of both the cartilage lesions and synovial inflammation was significantly decreased in the L-NIL-treated dogs. Treatment with L-NIL also significantly decreased both collagenase and general metalloprotease activity in the cartilage and the levels of IL-1beta, PGE2, and nitrite/nitrate in synovial fluid. CONCLUSION: This study demonstrated the effectiveness of a selective inhibitor of iNOS, L-NIL, in attenuating the progression of experimental OA. The data suggest that L-NIL may act by reducing the activity of metalloproteases in cartilage and the production of IL-1beta by synovium, both of which are known to play a major role in the pathophysiology of OA structural changes.

Animals↗
PubMed1998

The effects of tenidap on canine experimental osteoarthritis: II. Study of the expression of collagenase-1 and interleukin 1beta by in situ hybridization.

OBJECTIVE: To examine the effect of tenidap on the expression of collagenase- and interleukin 1beta (IL-1beta) genes in experimental canine osteoarthritis (OA). METHODS: The anterior cruciate ligaments of the right stifle joints of experimental dogs were sectioned by a stab wound incision and tissues samples were taken. Four dogs had received no treatment, 4 were treated with oral omeprazole (20 mg/day), and another 4 were treated with tenidap (3 mg/kg/bid) and omeprazole (20 mg/day). The dogs received medication for 8 weeks; all dogs were sacrificed at the end of this period. Tissues from 4 healthy dogs were used as controls. IL-1beta and collagenase-1 gene expression were measured in synovial membrane (synovial lining cells and mononuclear cell infiltrate) and collagenase-1 expression in cartilage using in situ hybridization techniques. Results were calculated as the percentage of cells expressing the gene, and expressed as cell score. RESULTS: The collagenase-1 cell score in the full thickness samples was significantly higher in OA cartilage than in normal cartilage, both in condyles and plateaus (p < 0.0002). Tenidap treated dogs showed a significantly lower cell score in femoral condyles and tibial plateaus in the superficial (p < 0.0002), deep (p < 0.005, p < 0.002, respectively), and full thickness (p < 0.0002) layers compared to OA dogs. No staining for collagenase-1 was observed in normal membrane. In OA synovial membrane, the collagenase-1 cell score was high in both the synovial lining cells and mononuclear cell infiltrate. Tenidap treated dogs showed a significantly lower score compared to OA tissue in both the synovial lining cells (p < 0.03) and the mononuclear cell infiltrate (p < 0.03). The relative decrease in the collagenase-1 cell score in the tenidap treated dogs was more pronounced in the mononuclear cell infiltrate. Staining for IL-1beta was observed in only a few lining cells in normal synovial membrane from unoperated dogs. In OA synovial membrane from untreated dogs, staining for IL-1beta was intense and was found in all dog specimens. The cell score was significantly higher in OA lining cells (p < 0.03) and mononuclear cell infiltrate (p < 0.03) compared to normal. In tenidap treated dogs, the score for IL-1beta was significantly lower than in OA, both in synovial lining cells (p < 0.03) and mononuclear cell infiltrate (p < 0.03). CONCLUSION: Tenidap significantly reduced in vivo expression of collagenase-1 and IL-1beta in experimental OA. These data are an extension of our previous study and showed that tenidap exerts its protective effects on OA lesions, likely by reducing the catabolic pathways of the disease.

Animals↗