Actividad in vitro de ertapenem frente a cepas bacterianas clínicas aisladas en 69 centros médicos españoles (Estudio E-test®) / In vitro activity of ertapenem against clinical bacterial isolates in 69 Spanish medical centers (E-test® study)

Este estudio se realizó para evaluar la actividad in vitro de ertapenem frente a cepas bacterianas clínicas aisladas de infecciones intraabdominalesy de vías respiratorias bajas, extrahospitalarias, en España en 2003. Puesto que el estudio se efectuó antes de la comercialización del ertapenem,también fue útil para definir el patrón de sensibilidad basal al ertapenem en cada uno de los hospitales participantes para estudiosde vigilancia posteriores. Cada centro participante definió un número variable de cepas bacterianas aerobias y facultativas aisladas en dichasinfecciones utilizando procedimientos habituales. Para determinar la concentración mínima inhibitoria (CMI) del ertapenem se utilizaron tirasreactivas de E-test®, mientras que para los otros antibióticos se emplearon técnicas de dilución cuantitativas o procedimientos de difusión cualitativos,según la práctica habitual de cada laboratorio de microbiología. Para interpretar los valores de la CMI se utilizaron los puntos de cortepara clasificación de la sensibilidad proporcionados por el CLSI. Se estudiaron 2901 cepas clínicas recientes aisladas de pacientes con infecciónintraabdominal o neumonía extrahospitalarias ingresados en 69 hospitales españoles: 2039 bacterias gramnegativas (1646 enterobacterias,216 hemófilos, 123 bacilos gramnegativos no fermentadores [BGNNF] y 54 de otros tipos) y 862 bacterias grampositivas (556 neumococos,159 estafilococos, 96 estreptococos distintos de S. pneumoniae, 44 enterococos y 7 de otro tipo). El ertapenem fue muy activo invitro frente a enterobacterias (99,8% sensibles), hemófilos (96,3% sensibles), neumococos (99,6% sensibles, de los que el 31% eran cepas nosensibles a la penicilina), estreptococos distintos de S. pneumoniae (99% sensibles) y estafilococos sensibles a la meticilina (94,8% sensibles)...(AU)

This study was conducted to assess the in vitro activity of ertapenem against clinical bacterial isolates from patients with community-acquiredintra-abdominal and lower tract respiratory infections in Spain in 2003. As the study was conducted before the marketing of ertapenem, itwas also useful to define a baseline susceptibility pattern for ertapenem in each of the participating hospitals for later surveillance studies.Each partipating site identified a variable number of aerobic and facultative bacteria isolated from patients with community-acquired intra-abdominal infection or pneumonia using standard procedures. E-test® strips were used for determining the minimum inhibitory concentration(MIC) of ertapenem, while for other antimicrobials either quantitative dilution techniques or qualitative diffusion procedures were used accordingto each microbiology laboratory’s routine practice. MIC breakpoints for categorization of susceptibility provided by the CLSI were usedfor interpreting MIC values. A total of 2,901 recent clinical isolates from patients with community-acquired intra-abdominal infection or pneumoniahospitalized in 69 Spanish medical centers were tested. These isolates included 2,039 Gram-negative bacteria (1,646 Enterobacteriaceae,216 Haemophilus, 123 non-fermenting Gram-negative bacteria [NFGNB] and 54 others) and 862 Gram-positive bacteria (556 pneumococci,159 staphylococci, 96 streptococci other than S. pneumoniae, 44 enterococci and 7 others). Ertapenem was very active in vitroagainst Enterobacteriaceae (99.8% susceptible), Haemophilus (96.3% susceptible), pneumococci (99.6% susceptible, of which 31% were penicillinnon-susceptible strains), streptococci other than S. pneumoniae (99.0% susceptible) and methicillin-susceptible staphylococci (94.8%susceptible)...(AU)

[In vitro activity of ertapenem against clinical bacterial isolates in 69 Spanish medical centers (E-test study)]. / Actividad in vitro de ertapenem frente a cepas bacterianas clínicas aisladas en 69 centros médicos españoles (Estudio E-test).

This study was conducted to assess the in vitro activity of ertapenem against clinical bacterial isolates from patients with community-acquired intra-abdominal and lower tract respiratory infections in Spain in 2003. As the study was conducted before the marketing of ertapenem, it was also useful to define a baseline susceptibility pattern for ertapenem in each of the participating hospitals for later surveillance studies. Each partipating site identified a variable number of aerobic and facultative bacteria isolated from patients with community-acquired intra-abdominal infection or pneumonia using standard procedures. E-test strips were used for determining the minimum inhibitory concentration (MIC) of ertapenem, while for other antimicrobials either quantitative dilution techniques or qualitative diffusion procedures were used according to each microbiology laboratory's routine practice. MIC breakpoints for categorization of susceptibility provided by the CLSI were used for interpreting MIC values. A total of 2,901 recent clinical isolates from patients with community-acquired intra-abdominal infection or pneumonia hospitalized in 69 Spanish medical centers were tested. These isolates included 2,039 Gram-negative bacteria (1,646 Enterobacteriaceae, 216 Haemophilus, 123 non-fermenting Gram-negative bacteria [NFGNB] and 54 others) and 862 Gram-positive bacteria (556 pneumococci, 159 staphylococci, 96 streptococci other than S. pneumoniae, 44 enterococci and 7 others). Ertapenem was very active in vitro against Enterobacteriaceae (99.8% susceptible), Haemophilus (96.3% susceptible), pneumococci (99.6% susceptible, of which 31% were penicillin non-susceptible strains), streptococci other than S. pneumoniae (99.0% susceptible) and methicillin-susceptible staphylococci (94.8% susceptible). For other Gram-positive and Gram-negative pathogens for which ertapenem susceptible breakpoints have not been defined, MIC(90) values were 0.38 and 0.064 mg/l, respectively. As expected, ertapenem had minimal activity in vitro against NFGNB, enterococci and methicillin-resistant staphylococci (MIC(90) of >32 mg/l for all three). Ertapenem was highly active in vitro against most bacteria isolated from patients with community-acquired intra-abdominal and lower respiratory tract infections.

[Patterns of susceptibility to antibiotics of Enterobacteriaceae causing intra-abdominal infection in Spain: SMART 2003 study outcomes]. / Patrones de sensibilidad a antimicrobianos de Enterobacteriaceae causantes de infecciones intraabdominales en España: resultados del estudio SMART 2003.

SMART (Study for Monitoring Antimicrobial Resistance Trends) is an ongoing global antimicrobial surveillance program focused on clinical isolates from intra-abdominal infections. The objective of this subanalysis was to assess antimicrobial susceptibility patterns among Entero-bacteriaceae recovered at 13 participating Spanish sites during 2003. Antimicrobial susceptibility testing was performed using broth microdilution techniques according to the CLSI (formerly NCCLS) guidelines for MIC testing. The presence of extended-spectrum beta-lactamases (ESBL) was confirmed in isolates with a MIC of ceftriaxone, ceftazidime, or cefepime>or=2 mg/l by comparing cefepime MICs with and with-out clavulanate. A total of 981 Enterobacteriaceae recovered from 840 patients were tested, of which 398 (41%) were community-acquired. Escherichia coli was the most common isolate (571 isolates; 58%), followed by Klebsiella spp. (153; 16% Enterobacter spp. (97; 10%), and Proteus spp. (63; 6%). A total of 191 isolates (19%) from 176 patients produced inducible beta-lactamases. The carbapenems and amikacin were the most consistently active agents against the Enterobacteriaceae (susceptibility>or=99%). Resistance rates for ceftazidime, cipro-floxacin, and levofloxacin exceeded 10%. ESBLs were detected phenotypically in 61 (6%) isolates, being the most common E. coli (61%), Klebsiella spp. (20%), and Enterobacter spp. (8%). Antimicrobial resistance among Enterobacteriaceae isolated from intra-abdominal infections is a problem in Spain. A significant proportion of inducible beta-lactamase and ESBL-producing Enterobacteriaceae causing intra-abdominal infection were acquired in the community. The carbapenems ertapenem, imipenem and meropenem and the aminoglycoside amikacin were highly active in vitro against Enterobacteriaceae isolated from intra-abdominal sites, including ESBL-producing organisms.

Patrones de sensibilidad a antimicrobianos de Enterobacteriaceae causantes de infecciones intraabdominales en España: resultados del estudio SMART 2003 / Patterns of susceptibility to antibiotics of Enterobacteriaceae causing intra-abdominal infections in Spain: SMART 2003 study outcomes

El estudio SMART ( Study for Monitoring Antimicrobial Resistance Trends ) es un programa mundial de vigilancia de la resistencia a los antimicrobianos de microorganismos aislados de infecciones intraabdominales. En este subanálisis se evaluó el patrón de sensibilidad de las enterobacterias recogidas en los 13 centros españoles participantes en el año 2003. Se determinaron las CMI de diferentes antimicrobianos por el método de microdilución en caldo siguiendo las recomendaciones del CLSI (antes NCCLS). Se confirmó la presencia de betalactamasas de espectro extendido (BLEE) en aquellas cepas frente a las cuales las CMI de ceftriaxona, ceftazidima y cefepima eran ≥2 mg/l mediante la comparación de las CMI de cefepima con o sin ácido clavulánico (10 mg/l). Se evaluaron 981 enterobacterias de 840 pacientes. De ellas, 398 (41%) eran de adquisición comunitaria. Escherichia coli fue el aislamiento más frecuente (571 cepas; 58%), seguida por Klebsiella spp. (153 cepas; 16%), Enterobacter spp. (97 cepas; 10%) y Proteus spp. (63 cepas; 6%). Un total de 191 cepas procedentes de 176 pacientes eran productoras de betalactamasas inducibles (19%). Los carbapenémicos y la amikacina fueron los antibióticos más activos frente a las enterobacterias (sensibilidad ≥99%). La resistencia a ceftazidima, ciprofloxacino y levofloxacino fue superior al 10%. Se detectaron BLEE fenotípicamente en 61 (6%) de los aislamientos, siendo más frecuentes en E. coli (61%), Klebsiella spp. (20%) y Enterobacter spp. (8%). La resistencia entre las enterobacterias aisladas de infecciones intraabdominales constituye un problema en España. Una proporción significativa de las productoras de BLEE o de betalactamasas inducibles proceden de la comunidad. Los carbapenémicos ertapenem, imipenem y meropenem, y el aminoglucósido amikacina, son muy activos in vitro frente a las enterobacterias aisladas de focos intraabdominales, incluyendo aquéllas productoras de BLEE

SMART (Study for Monitoring Antimicrobial Resistance Trends) is an ongoing global antimicrobial surveillance program focused on clinical isolates from intra-abdominal infections. The objective of this subanalysis was to assess antimicrobial susceptibility patterns among Enterobacteriaceae recovered at 13 participating Spanish sites during 2003. Antimicrobial susceptibility testing was performed using broth microdilution techniques according to the CLSI (formerly NCCLS) guidelines for MIC testing. The presence of extended-spectrum beta-lactamases (ESBL) was confirmed in isolates with a MIC of ceftriaxone, ceftazidime, or cefepime >2 mg/l by comparing cefepime MICs with and without clavulanate. A total of 981 Enterobacteriaceae recovered from 840 patients were tested, of which 398 (41%) were community-acquired. Escherichia coli was the most common isolate (571 isolates; 58%), followed by Klebsiella spp. (153; 16%), Enterobacter spp. (97; 10%), and Proteus spp. (63; 6%). A total of 191 isolates (19%) from 176 patients produced inducible beta-lactamases. The carbapenems and amikacin were the most consistently active agents against the Enterobacteriaceae (susceptibility >99%). Resistance rates for ceftazidime, ciprofloxacin, and levofloxacin exceeded 10%. ESBLs were detected phenotypically in 61 (6%) isolates, being the most common E. coli (61%), Klebsiella spp. (20%), and Enterobacter spp. (8%). Antimicrobial resistance among Enterobacteriaceae isolated from intra-abdominal infections is a problem in Spain. A significant proportion of inducible beta-lactamase and ESBL-producing Enterobacteriaceae causing intra-abdominal infection were acquired in the community. The carbapenems ertapenem, imipenem and meropenem and the aminoglycoside amikacin were highly active in vitro against Enterobacteriaceae isolated from intra-abdominal sites, including ESBL-producing organisms

Inhibition of Trypanosoma cruzi hexokinase by bisphosphonates.

Hexokinase is the first enzyme involved in glycolysis in most organisms, including the etiological agents of Chagas disease (Trypanosoma cruzi) and African sleeping sickness (Trypanosoma brucei). The T. cruzi enzyme is unusual since, unlike the human enzyme, it is inhibited by inorganic diphosphate (PPi). Here, we show that non-hydrolyzable analogues of PPi, bisphosphonates, are potent inhibitors of T. cruzi hexokinase (TcHK). We determined the activity of 42 bisphosphonates against TcHK, and the IC(50) values were used to construct pharmacophore and comparative molecular similarity indices analysis (CoMSIA) models for enzyme inhibition. Both models revealed the importance of electrostatic, hydrophobic, and steric interactions, and the IC(50) values for 17 active compounds were predicted with an average error of 2.4x by using the CoMSIA models. The compound most active against T. cruzi hexokinase was found to have a 2.2 microM IC(50) versus the clinically relevant intracellular amastigote form of T. cruzi, but only a approximately 1-2 mM IC(50) versus Dictyostelium discoideum and a human cell line, indicating selective activity versus T. cruzi.

Successful treatment of rhinocerebral zygomycosis with a combination of caspofungin and liposomal amphotericin B.

Genera of the order Mucorales (Rhizopus, Mucor, Rhizomucor, Absidia, Apophysomyces, Cunninghamella, and Saksenaea) cause an angioinvasive infection called zygomycosis. Mortality rates can approach 100% depending on the patient's underlying disease and form of zygomycosis. We report here on the unusual case of a patient with acute myelogenous leukemia and zygomycosis unresponsive to monotherapy with liposomal amphotericin B, who responded favorably following the addition of the echinocandin caspofungin acetate.

Safety of the concomitant use of caspofungin and cyclosporin A in patients with invasive fungal infections.

Caspofungin, an echinocandin antifungal agent, is active against invasive Aspergillus and Candida infections. In a phase I study in healthy volunteers, mild transient increases in serum aminotransferases were observed with the concomitant administration of caspofungin and cyclosporin A (CsA). As a result, it is recommended that the concomitant use of the two drugs be limited to those settings with appropriate risk-benefit balance. We retrospectively assessed safety data in 14 patients with refractory invasive mycoses who were treated concomitantly with CsA and caspofungin before the drug was licensed in Spain. In all, 13 patients were adults (median age, 31.5 years; range, 14-67 years). The average duration of concomitant therapy was 15 days (range, 2-43 days). No clinically significant elevations of serum aminotransferases were observed, and no patient had concomitant therapy discontinued or interrupted due to a drug-related adverse event. In this study of a limited number of patients, the coadministration of caspofungin and CsA was generally well tolerated.

Primary hepatic lymphoma: favorable outcome after combination chemotherapy.

BACKGROUND: Primary hepatic non-Hodgkin lymphoma (PHL) is a rare and difficult to diagnose lymphoproliferative disorder of unknown etiology. It is believed that the prognosis in affected patients is dismal, consisting of early recurrence and short survival. METHODS: A retrospective cohort review of patients with PHL diagnosed between 1974 and 1995 at a university cancer center was performed. RESULTS: Twenty-four patients with PHL were identified. Typically, the disease occurred in middle-aged men (median age, 50 years). The primary presenting complaint was right upper quadrant abdominal pain, with hepatomegaly found at physical examination. Serum liver enzymes, lactate dehydrogenase, and beta-2-microglobulin levels all were elevated, but alpha-fetoprotein and carcinoembryonic antigen levels were within normal range. Hypercalcemia was found in 6 of 15 patients who were tested. Six of 10 patients who were tested were positive for the hepatitis C virus (HCV). Liver scans demonstrated either a solitary lesion or multiple lesions. Pathologic examination revealed diffuse large cell lymphoma in 23 patients (96%). Combination chemotherapy was the mainstay of treatment; surgery consisted of diagnostic biopsy. The complete remission rate was 83.3%, and the 5-year cause specific and failure free survival rates were 87.1% and 70.1%, respectively. HCV infection did not appear to influence the outcome of therapy. CONCLUSIONS: The outcome of patients with PHL who are treated with combination chemotherapy may be more favorable than that reported elsewhere. The frequent association of PHL with HCV infection observed in this series warrants further investigation.

[Hematopoietic stem cell transplantation as salvage treatment in patients with aggressive non-Hodgkin's lymphoma]. / Trasplante de células progenitoras hematopoyéticas como tratamiento de rescate en pacientes con linfomas no hodgkinianos agresivos.

BACKGROUND: The indication of early hematopoietic stem cell transplantation (HSCT) in patients with aggressive non-Hodgkin's lymphoma (LNH) is controversial. PATIENTS AND METHODS: Retrospective analysis of 86 patients with aggressive NHL treated with MACOP/VACOP-B chemotherapy. HSCT was performed as salvage treatment to patients under 65 years of age with progressive disease or chemosensitive relapse. Progression free survival (PFS) and overall survival (OS) were determined by the Kaplan-Meier method. Rates of response and survival functions were compared between the International Prognostic Index (IPI) groups using the Chi-square and log-rank tests, respectively. RESULTS: Patients median age was 48 years; 22% had T cell NHL and 57% had intermediate-high and high risk (high risk) IPI. There were 6 toxic deaths (7%), and treatment failure was observed in 42 patients (48.8%). Thirty one of them were candidates for TPH due to age under 65 years, although 21 were finally transplanted (including 13 with high risk IPI). A significant association between PFS and IPI was observed, 61.9% for low risk (low and low-intermediate) versus 28.2% for high risk groups (p = 0.0007). With a median follow up of 4.8 years, OS was 64%; 80.5% for low risk versus 52.6% for high risk IPI groups (p = 0.01), and 83.7% versus 62% for the same groups in patients under 65 years of age (p = 0.02). The median follow up after failure to chemotherapy was 42.7 months. CONCLUSIONS: In this retrospective study, OS rate in high risk IPI patients with NHL using HSCT as salvage treatment is similar to that reported using HSCT during earlier phases of treatment.

Plasma endothelin-1 levels after stem cell transplantation.

Acute renal failure and veno-occlusive disease of the liver are serious complications following stem cell transplantation (SCT) and contribute to the non-relapse mortality associated with this procedure. Endothelins, a family of vasoconstrictor peptides, may be involved in the pathogenesis of a variety of renal and hepatic diseases, including CsA-associated hypertension and the hepatorenal syndrome. In order to study the relevance of endothelins to SCT-related liver and kidney dysfunction, we determined endothelin-1 (ET-1) levels in plasma samples obtained from 65 patients (38 autologous, 27 allogeneic) 7 days before and 7, 14 and 28 days after SCT. A steady increase in plasma ET-1 was observed after SCT (5.36 pg/ml, 95% CI 4.30-6.43 on day +28 vs 3.82 pg/ml, 95% CI 3.21-4.43 on day -7; P = 0.020). No differences in ET-1 levels existed between autologous and allogeneic SCT recipients at any of the time points studied (P = 0.561). In addition, no significant differences were observed among patients with renal dysfunction vs those without (P = 0.187), nor in patient groups with or without hepatic dysfunction (P = 0.075). In conclusion, even though plasma ET-1 levels showed a steady increase following SCT, no correlation could be found with development of SCT-related kidney or liver dysfunction.

Long-term management of homozygous protein C deficiency: replacement therapy with subcutaneous purified protein C concentrate.

We present the case of a full-term newborn in whom purpura fulminans developed shortly after birth. A diagnosis of homozygous protein C deficiency was established based upon undetectable plasma protein C activity and antigenemia in the newborn infant, and was later confirmed by protein C gene analysis. Specific replacement therapy with intravenous protein C concentrate was started 9 days after birth. This rapidly led to the complete regression of cutaneous lesions and consumption coagulopathy. After stabilization, oral anticoagulation was initiated in association with prophylactic treatment with intravenous protein C concentrate. However, oral anticoagulation was finally abandoned as the patient presented several thrombotic and hemorrhagic episodes clearly related to difficulties with anticoagulation. Due to the hazards related to prolonged venous access, we are currently using subcutaneous infusion of protein C concentrate for the long-term management of this condition, with satisfactory results.

Interferon alpha for chronic myeloid leukemia relapsing after allogeneic bone marrow transplantation.

Interferon alpha (IFN alpha) induces cytogenetic responses in patients with chronic myeloid leukemia (CML) who relapse after allogeneic bone marrow transplantation (BMT). The purpose of this study was to analyze the therapeutic role of IFN alpha in this setting. The experience of a single institution and the published results on this topic were evaluated. We have included patients who received IFN alpha as a single agent, excluding those patients who received previous or simultaneous donor leukocyte infusions. The outcomes of 11 patients treated in our center and those of 108 previously reported patients have been analyzed. Five out of 11 patients treated in our institution obtained a complete cytogenetic response (CGR). Two patients continue in complete cytogenetic response 3.5 and 8.2 years later, and the qualitative RT-PCR is negative for bcr-abl RNA. The CGR has been transient in one patient, and follow-up is short in the other two. Secondary effects have been acceptable, with myelosuppression as the main toxic effect. Graft-versus-host disease did not occur. The literature review identified 108 patients treated with IFN alpha as sole therapy for relapsed CML. Cytogenetic response and CGR seem to be better in patients with cytogenetic relapse, as compared to patients with hematologic relapse (61% vs. 45% and 45% vs. 28%, respectively). Several patients remained in CGR for more than 5 years. This overview also suggests that CGR is more frequent when IFN alpha is used in patients relapsing after non T-depleted BMT. IFN alpha induces complete cytogenetic response in nearly half of the patients with CML who relapse after allogeneic BMT, with acceptable toxicity. We believe that these results using IFN alpha as a front-line therapy for CML relapsing after BMT warrant a randomized comparison with donor lymphocyte infusions.

[Treatment of leukemia relapsed after allogenic bone marrow transplantation with donor lymphocyte infusion: report of 11 cases]. / Tratamiento de la recidiva leucémica post-trasplante alogénico de medula ósea con infusión de leucocitos del donante: a propósito de 11 casos.

PURPOSE: Donor leukocyte infusions (DLI) are useful for treating leukaemic relapse after allogeneic bone marrow transplantation (BMT). We reviewed our experience with eleven patients who received DLI between 1995 and 1997. PATIENTS AND METHODS: The diagnoses prior to DLI were: chronic myeloid leukaemia (CML) in chronic phase (CP) (two patients) or accelerated phase (two patients), acute myeloid leukaemia (AML) (two patients), acute lymphoid leukaemia (ALL) (two patients), and refractory anaemia with excess blasts under transformation (tRAEB) (three patients). The patients received a median of 1.72 x 10(8) CD3+ cells/Kg (range: 0.58 x 10(8) CD3+ cells/Kg). Four patients were infused cryopreserved cells. Six patients received interferon alpha (IFN alpha) concomitantly. RESULTS: Seven patients (four CML, one AML, one ALL, one tRAEB) obtained complete remission (CR). Graft-versus-host disease (GVHD) was observed in all patients with CR and one without response. Marrow hypoplasia or severe bicytopenia occurred in four patients. Of all patients achieving CR, two died after relapsing within 3 months of DLI, while three others died of GVHD. Four patients had no response to DLI or were not evauable. Only two patients--both with CML--are alive 1096 and 374 days after DLI, the former in clinical, cytogenetic and molecular CR, and the latter in second CP after 2 months in CR. CONCLUSIONS: DLI results in CR in most patients with relapsing leukaemia or myelodysplasia after BMT, especially in CML patients. The anti-leukaemia effect is highly correlated with GVHD. This complication and marrow hypoplasia remain major causes of morbidity and mortality of this procedure.

Development of survival responsiveness to brain-derived neurotrophic factor, neurotrophin 3 and neurotrophin 4/5, but not to nerve growth factor, in cultured motoneurons from chick embryo spinal cord.

During embryonic development, most neuronal populations undergo a process usually referred to as naturally occurring neuronal death. For motoneurons (MTNs) of the lumbar spinal cord of chick embryos, this process takes place in a well defined period of time, between embryonic days 6 and 10 (E6-E10). Neurotrophins (NTs) are the best characterized family of neurotrophic factors and exert their effects through activation of their specific Trk receptors. In vitro and in vivo studies have demonstrated that rodent motoneurons survive in response to BDNF, NT3, and NT4/5. In contrast, the trophic dependencies of chicken motoneurons have been difficult to elucidate, and various apparently conflicting reports have been published. In the present study, we describe how freshly isolated motoneurons from E5.5 chick embryos did not respond to any neurotrophin in vitro. Yet, because motoneurons were maintained alive in culture in the presence of muscle extract, they developed a delayed specific survival response to BDNF, NT3, and NT4/5 that is clearly dose-dependent, reaching saturation at doses of 100 pg/ml. This trophic response correlated with increasing expression of the corresponding functional receptors TrkB and TrkC. Moreover, TrkB receptor is able to become autophosphorylated and to activate classical intracellular signaling pathways such as the extracellular signal-regulated protein kinase when it is stimulated with its cognate ligand BDNF. Therefore, our results reconcile the reported differences between in vivo and in vitro studies on the ability of chicken MTNs to respond to some members of the neurotrophin family of trophic factors.

Effects of interferon-gamma and tumor necrosis factor alpha on the expression of the genes encoding aggrecan, biglycan, and decorin core proteins in cultured human chondrocytes.

OBJECTIVE: To determine the effects of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), alone or in combination, on the expression of aggrecan, biglycan, and decorin core protein genes in human chondrocytes. METHODS: Isolated human chondrocytes were cultured on poly(2-hydroxyethyl methacrylate)-coated plastic dishes to prevent the loss of cartilage-specific phenotype, and the effects of IFN gamma and TNF alpha, alone or in combination, on aggrecan, biglycan, and decorin core protein gene transcription and steady-state messenger RNA (mRNA) levels were examined. RESULTS: The addition of IFN gamma (1.5 pM) or TNF alpha (0.3 pM) caused a decrease in the steady-state level of aggrecan mRNA (-25% and -15%, respectively), and the combination of these low-concentration cytokines caused a potent inhibition (-66%). These effects were the result of a decrease (-50%) in the transcription rate of the corresponding gene. At the concentrations used, IFN gamma did not alter the levels of biglycan mRNA or the transcription rates of the biglycan core protein gene. In contrast, TNF alpha decreased biglycan steady-state mRNA levels (-62%) and the biglycan core protein gene transcription rate (-18%). The combination of IFN gamma and TNF alpha resulted in a potentiation of the inhibitory effects of TNF alpha on biglycan mRNA levels (-79%) and transcription rate of the biglycan core protein gene (-46%). IFN gamma produced a modest decrease in decorin mRNA levels (-23%) and decorin core protein gene transcription rate (-17%). In contrast, TNF alpha resulted in a marked increase in decorin mRNA levels (+260%) that was not the result of transcriptional regulation. Notably, the combination of IFN gamma and TNF alpha potentiated the inhibitory effects of IFN gamma on decorin mRNA (-80%) and on the transcription of the corresponding gene (-43%). Similar results were obtained in fetal and adult articular chondrocytes. CONCLUSION: These data demonstrate that 1) the expression of the core protein genes encoding the cartilage proteoglycans aggrecan, biglycan, and decorin is differentially regulated by IFN gamma and TNF alpha; 2) these effects are mediated by transcriptional and posttranscriptional mechanisms; and 3) the combination of the 2 cytokines causes a potent inhibitory effect on the expression of the genes for the core proteins of these 3 proteoglycans, which occurs largely at the transcriptional level. The inhibition of aggrecan, decorin, and biglycan core protein gene expression by the combination of IFN gamma and TNF alpha may contribute to the cartilage destruction that is characteristic of inflammatory joint diseases.