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At least 163 records · Page 9Linked to original sources
PubMed2002

Indolo[2,3-b]-quinolizinium bromide: an efficient intercalator with DNA-photodamaging properties.

The associative interactions of indolo[2,3-b]-quinolizinium bromide with DNA and its DNA photocleavage properties were studied in detail. Absorption and emission spectroscopy, linear dichroism, and energy-transfer measurements indicate that the indoloquinolizinium binds to DNA primarily by intercalation, with a preference for GC base pairs. In agreement with this data, the results of primer extension analysis indicate that photocleavage occurrs prevalently at the GC nucleotides. Molecular modeling studies confirm that intercalative stacking between adjacent base pairs is energetically favorable. However, it is also observed that the location of the dye in the minor groove of the DNA is energetically even more favorable. Upon UVA irradiation, the indoloquinolizinium causes single-strand cleavage with an efficiency that varies with the dye-DNA ratio. This observation is rationalized in terms of more efficient photocleavage by the externally bound dye compared with the intercalated one. The kinetics of strand degradation under aerobic and anaerobic conditions suggest that a Type I reaction occurs, that is, radical-mediated DNA damage.

Autoradiography↗
PubMed2001

Organization of plasma membrane functional rafts upon T cell activation.

Raft microdomains have been shown to play a key role in T cell activation. We found that in human T lymphocytes the formation of functional rafts at the plasma membrane was induced by T cell priming. In resting T cells from peripheral blood Lck and the raft glycosphingolipid GM1 resided in intracellular membranes. T cell activation induced synthesis of GM1 and effector cells showed very high levels of this lipid, which became predominantly plasma membrane associated. TCR triggering also induced targeting of the cytosolic Lck to the plasma membrane. Thus, effector cells acquire an improved signaling machinery by increasing the amount of rafts at the plasma membrane. The fact that, when compared with naive T cells, memory T cells showed higher GM1 levels suggests that raft lipid synthesis may be developmentally regulated and tune T cell responsiveness.

G(M1) Ganglioside↗
PubMed2002

Vav cooperates with CD28 to induce NF-kappaB activation via a pathway involving Rac-1 and mitogen-activated kinase kinase 1.

CD28-delivered costimulatory signals are required to induce NF-kappaB activation in response to TCR stimulation. We have recently demonstrated that the mitogen-activated kinase kinase 1 (MEKK1), a kinase known to regulate the c-jun N-terminal kinase (JNK) pathway, is also involved in the CD28- and TCR-induced inhibitor of kappaB factor (IkappaB) kinases (IKK) and NF-kappaB activation. Searching for molecules that couple TCR and CD28 to MEKK1, we found that the guanine nucleotide exchange factor Vav synergized with CD28 stimulation in Jurkat cells to induce NF-kappaB transcriptional activity through the activation of IKKalpha and IKKbeta. Dominant negative mutants of Vav inhibited TCR- and CD28-NF-kappaB-dependent transcription by interfering with the activation of the IKK complex. Blocking Rac signaling downstream of Vav by dominant negative RacN17 exerts similar effects on IKK and NF-kappaB activation after TCR/CD28 stimulation. Finally, Vav-induced NF-kappaB activation in CD28 costimulated cells was inhibited by dominant negative MEKK(KM). These results identify Vav, Rac-1 and MEKK1 as components of a common pathway regulating both NF-kappaB and AP-1 that contributes to full activation of the CD28 response element (CD28RE).

CD28 Antigens↗
PubMed2002

Lipid rafts and T cell receptor signaling: a critical re-evaluation.

The current model suggesting that raft integrity is required for T cell activation is mostly (but not exclusively) based on the use of drugs, such as methyl-beta-cyclodextrin (M beta CD), that disorganize rafts and inhibit T cell receptor (TCR)-induced Ca2+ influx. Here we show that conditions that disrupt lipid raft integrity do not inhibit TCR triggering in Jurkat cells and normal T lymphocytes. Indeed, we found that the reported inhibition of TCR-induced Ca2+ influx by M beta CD treatment is mainly due to (a) nonspecific depletion of intracellular Ca2+ stores and (b) plasma membrane depolarization of T cells. When these side-effects are taken into account, raft disorganization does not alter TCR-dependent Ca2+ signaling. In line with these results, also TCR-induced tyrosine phosphorylation is not inhibited by dispersion of lipid rafts. By contrast, in the same conditions, Ca2+ signaling via the glycosylphosphatidylinositol (GPI)-anchored protein CD59 is totally abolished. These results indicate that, while signaling through GPI-anchored proteins requires lipid raft integrity, CD3-dependent TCR activation occurs independently of cholesterol extraction.

CD59 Antigens↗
PubMed1999

Marked and sustained improvement two years after autologous stem cell transplantation in a girl with systemic sclerosis.

Autologous transplantation of hematopoietic stem cells has recently been proposed as a possible treatment for autoimmune diseases that are associated with a very severe prognosis. A 12-year-old girl who, since 4 years of age, had systemic sclerosis with progressive pulmonary involvement underwent autologous peripheral blood-derived stem cell transplantation (aPBSCT) using CD34+ selection, cyclophosphamide, and the infusion of the monoclonal antibody CAMPATH-1G. Following transplantation, in the absence of any treatment other than symptomatic therapy, the patient's exertional dyspnea and alveolitis disappeared and she experienced a marked improvement in skin score, height velocity, and general well-being that has persisted 2 years after the transplantation procedure. Autologous PBSCT associated with the infusion of the monoclonal antibody CAMPATH-1G appears to be a useful therapy for otherwise intractable forms of progressive systemic sclerosis.

Adolescent↗
PubMed2000

L-aspartase: new tricks from an old enzyme.

The enzyme L-aspartate ammonia-lyase (aspartase) catalyzes the reversible deamination of the amino acid L-aspartic acid, using a carbanion mechanism to produce fumaric acid and ammonium ion. Aspartase is among the most specific enzymes known with extensive studies failing, until recently, to identify any alternative amino acid substrates that can replace L-aspartic acid. Aspartases from different organisms show high sequence homology, and this homology extends to functionally related enzymes such as the class II fumarases, the argininosuccinate and adenylosuccinate lyases. The high-resolution structure of aspartase reveals a monomer that is composed of three domains oriented in an elongated S-shape. The central domain, comprised of five-helices, provides the subunit contacts in the functionally active tetramer. The active sites are located in clefts between the subunits and structural and mutagenic studies have identified several of the active site functional groups. While the catalytic activity of this enzyme has been known for nearly 100 years, a number of recent studies have revealed some interesting and unexpected new properties of this reasonably well-characterized enzyme. The non-linear kinetics that are seen under certain conditions have been shown to be caused by the presence of a separate regulatory site. The substrate, aspartic acid, can also play the role of an activator, binding at this site along with a required divalent metal ion. Truncation of the carboxyl terminus of aspartase at specific positions leads to an enhancement of the catalytic activity of the enzyme. Truncations in this region also have been found to introduce a new, non-enzymatic biological activity into aspartase, the ability to specifically enhance the activation of plasminogen to plasmin by tissue plasminogen activator. Even after a century of investigation there are clearly a number of aspects of this multifaceted enzyme that remain to be explored.

Amination↗
PubMed2003

De novo 1q32q44 duplication and distal 1q trisomy syndrome.

We report on an infant with minor anomalies and a de novo 1q duplication. The chromosomal abnormality was diagnosed prenatally after sonographic detection of cerebral ventriculomegaly and bilateral choroid plexus cysts in the fetus. The amniocentesis showed an abnormal male karyotype, 46,XY,dup(1)(q32q44), subsequently confirmed by fluorescence in situ hybridization using whole chromosome paint 1 and comparative genomic hybridization. The baby, born at 37 weeks of gestation, had wide cranial sutures and large fontanelles, sloping forehead, hypertelorism, short and downward-slanting palpebral fissures, a high-arched and narrow palate, malformed ears, and long feet with overriding second and third toes. This is the sixth case of known duplication involving the 1q32q44 segment; the physical findings in the case reported herein are similar to those of other patients reported previously, providing further evidence of the existence of the "distal 1q trisomy" phenotype.

Abnormalities, Multiple↗
PubMed2004

Hepatic fibrosis in Kabuki syndrome.

Kabuki (Niikawa-Kuroki) syndrome (KS) is characterized by a distinctive face, mental retardation, growth deficiency, skeletal anomalies, dermatoglyphic abnormalities, palatal anomalies, congenital heart defects, and urogenital malformations. Congenital hepatic abnormalities have been sporadically described in patients with KS from the literature, consisting of extrahepatic biliary atresia, neonatal sclerosing cholangitis, and severe neonatal jaundice. We report here on an additional patient with a congenital abnormality of the liver consisting of hepatic fibrosis. To our knowledge, idiopathic congenital hepatic fibrosis has not been reported in KS. Thus, our observation expands the spectrum of liver malformations found in KS with the inclusion of hepatic fibrosis and supports the evidence that hepatic abnormalities may not be uncommon in KS. Clinician should be advised to search for the specific facial anomalies of KS in patients with syndromic congenital hepatic diseases, and KS should be added to the list of previously recognized multiple congenital anomaly syndromes with hepatic involvement. Due to the frequent association with congenital heart malformations, KS should be considered in the evaluation of patients with neonatal liver disease and cardiac malformation. Due to the expression patterns of Notch genes, involvement of the Notch signaling pathway in the development of heart and liver anomalies in KS should be considered.

Abnormalities, Multiple↗
PubMed2006

Block of neural Kv1.1 potassium channels for neuroinflammatory disease therapy.

OBJECTIVE: We asked whether blockade of voltage-gated K+ channel Kv1.1, whose altered axonal localization during myelin insult and remyelination may disturb nerve conduction, treats experimental autoimmune encephalomyelitis (EAE). METHODS: Electrophysiological, cell proliferation, cytokine secretion, immunohistochemical, clinical, brain magnetic resonance imaging, and spectroscopy studies assessed the effects of a selective blocker of Kv1.1, BgK-F6A, on neurons and immune cells in vitro and on EAE-induced neurological deficits and brain lesions in Lewis rats. RESULTS: BgK-F6A increased the frequency of miniature excitatory postsynaptic currents in neurons and did not affect T-cell activation. EAE was characterized by ventriculomegaly, decreased apparent diffusion coefficient, and decreased (phosphocreatine + beta-adenosine triphosphate)/inorganic phosphate ratio. Reduced apparent diffusion coefficient and impaired energy metabolism indicate astrocytic edema. Intracerebroventricularly BgK-F6A-treated rats showed attenuated clinical EAE with unexpectedly reduced ventriculomegaly and preserved apparent diffusion coefficient values and (phosphocreatine + beta-adenosine triphosphate)/inorganic phosphate ratio. Thus, under BgK-F6A treatment, brain damage was dramatically reduced and energy metabolism maintained. INTERPRETATION: Kv1.1 blockade may target neurons and astrocytes, and modulate neuronal activity and neural cell volume, which may partly account for the attenuation of the neurological deficits. We propose that Kv1.1 blockade has a broad therapeutic potential in neuroinflammatory diseases (multiple sclerosis, stroke, and trauma).

Animals↗
PubMed2002

Proinflammatory responses to self HLA epitopes are triggered by molecular mimicry to Epstein-Barr virus proteins in oligoarticular juvenile idiopathic arthritis.

OBJECTIVE: To evaluate whether abnormal T cell recognition may be generated by exposure to exogenous antigens presenting sequence homology with epitopes contained in self HLA alleles, and if such recognition may be part of the mechanisms that fuel inflammation in autoimmune diseases associated with certain HLA alleles. METHODS: Cytotoxic responses of peripheral blood mononuclear cells to 9-mer peptides derived from HLA molecules (DRB1*1101, DRB1*0801, or DPB1*0201) associated with oligoarticular juvenile idiopathic arthritis (JIA) or homologous peptides derived from Epstein-Barr virus (EBV) proteins (Bolf1 or Balf2) were analyzed in patients with oligoarticular JIA and in healthy controls matched for HLA-DRB1*1101, DRB1*0801, or DPB1*0201. Production of proinflammatory cytokines in culture supernatants was determined by enzyme-linked immunosorbent assay. RESULTS: T cell cytotoxic responses and production of proinflammatory cytokines in response to stimulation with self HLA-derived peptides were found only in patients with oligoarticular JIA, and not in controls. Patients with oligoarticular JIA, but none of the healthy controls, had EBV-self HLA cross-reactive T cells. CONCLUSION: Our data suggest a disease- and allele-specific mechanism of autoimmunity in oligoarticular JIA. This mechanism may be part of the pathogenesis of the disease, and could be the basis of one of the likely multiple candidates for antigen-specific immunotherapy approaches in the future.

Adolescent↗
PubMed2003

Positive family history of psoriasis does not affect the clinical expression and course of juvenile idiopathic arthritis patients with oligoarthritis.

OBJECTIVE: In the 1997 revision of the International League of Associations for Rheumatology (ILAR) criteria for juvenile idiopathic arthritis (JIA), a family history of psoriasis is an exclusion for the oligoarthritis category. We investigated whether psoriasis in a first or second degree relative influences the clinical expression and course of JIA patients with oligoarthritis. METHODS: In a cross-sectional study, consecutive oligoarticular-onset JIA patients were investigated. Clinical evaluations included confirmation of a family history of psoriasis and assessment of nail abnormalities, dactylitis, psoriatic rash, variables of JIA activity, and laboratory indicators of inflammation. Retrospective assessments included sex, onset age, disease duration, antinuclear antibodies, HLA-B27, uveitis, ocular complications, second-line therapies, intraarticular corticosteroid injections, radiographic joint lesions, joint involvement over time, and laboratory investigations at disease presentation and first observation. RESULTS: A total of 185 patients were included. Thirty-three had a positive family history of psoriasis (group 2) and 139 did not (group 1). Thirteen patients fulfilled the ILAR criteria for juvenile psoriatic arthritis (group 3). Patients in groups 1 and 2 were comparable for all parameters, except for a higher frequency of females in group 1 (P = 0.04). As compared with group 2, patients in group 3 were less frequently antinuclear antibody positive and had a more severe arthritis and a different distribution of joint involvement. CONCLUSION: We found close similarities in the clinical features and course among patients with oligoarthritis who had a positive family history for psoriasis and those who did not. These findings argue against the exclusion of the former patients from the oligoarthritis category of JIA.

Arthritis, Juvenile↗
PubMed2003

Prognostic factors for radiographic progression, radiographic damage, and disability in juvenile idiopathic arthritis.

OBJECTIVE: To investigate the rate of radiographic progression and identify prognostic factors of radiographic progression, radiographic damage, and physical disability in juvenile idiopathic arthritis (JIA). METHODS: Ninety-four JIA patients with a median disease duration of 1.1 years were followed up prospectively for a median of 4.5 years. Bilateral wrist radiographs were obtained at baseline, at 1 year, and at the last followup visit. Radiographic damage was assessed by the carpal length (Poznanski score), and physical disability by the Childhood Health Assessment Questionnaire (C-HAQ). Yearly radiographic progression, the Poznanski score at the final visit, and the C-HAQ score at the final visit were used as outcome measures. Baseline parameters included demographic, clinical, laboratory, and radiographic data. RESULTS: The mean +/- SD Poznanski score was -1.2 +/- 1.3 at baseline, -1.7 +/- 1.8 at the 1-year visit, and -1.9 +/- 2.2 at the final visit (P < 0.0001). Radiographic progression was greater during the first year (mean +/- SD -0.5 +/- 1.1) than between the 1-year visit and the final visit (-0.2 +/- 1.3). The mean yearly radiographic progression during the entire study period was -0.1 +/- 0.4. Logistic regression analysis revealed that radiographic progression during the first year was the only baseline parameter that was predictive of all 3 study outcomes. The final Poznanski score was also predicted by the baseline Poznanski score, whereas female sex was protective against radiographic progression. CONCLUSION: We identified the prognostic factors for poorer outcome in polyarticular-course JIA. The changes in the early Poznanski score can be used to predict long-term joint damage and physical disability.

Adolescent↗
PubMed1987

Systemic lupus erythematosus with Jaccoud's arthropathy mimicking juvenile rheumatoid arthritis.

We describe a girl who presented at age 5 with objective signs of arthritis and was initially diagnosed as having juvenile rheumatoid arthritis. Over the following years, she developed slowly progressive joint deformities indicative of Jaccoud's arthropathy. When she was 11 years old, symptoms typical of systemic lupus erythematosus appeared, accompanied by anti-DNA antibodies. This case illustrates that in children also, Jaccoud's arthropathy may be a precocious manifestation of systemic lupus erythematosus.

Adolescent↗
PubMed2005

Patients with antinuclear antibody-positive juvenile idiopathic arthritis constitute a homogeneous subgroup irrespective of the course of joint disease.

OBJECTIVE: We recently hypothesized that in the International League of Associations for Rheumatology (ILAR) classification of juvenile idiopathic arthritis (JIA), the presumably homogeneous patient group characterized by early onset of disease, a female predilection, the presence of antinuclear antibodies (ANA), asymmetric arthritis, and the risk for iridocyclitis is classified into different categories. We sought to investigate whether ANA-positive patients belonging to the ILAR categories of oligoarthritis and rheumatoid factor (RF)-negative polyarthritis share homogeneous features and to compare these features with those of ANA-negative patients with JIA in the same categories. METHODS: We identified patients who were followed up during a 15-year period. All patients had JIA according to the ILAR criteria, with oligoarticular or polyarticular onset. ANA positivity was defined as 2 or more positive results at a titer of >or=1:160. Demographic and clinical features, including the number of joints involved over time and measures of JIA severity at the last followup visit, were recorded retrospectively. RESULTS: A total of 256 patients were included: 190 were ANA positive (109 had persistent oligoarthritis, 48 had extended oligoarthritis, and 33 had RF-negative polyarthritis), and 66 were ANA negative (35 had RF-negative polyarthritis, and 31 had oligoarthritis). All patients who were positive for ANA were similar in terms of age at disease presentation, female-to-male ratio, and frequency of symmetric arthritis and iridocyclitis. Compared with ANA-positive patients with polyarticular disease, ANA-negative patients with polyarticular arthritis were older at disease presentation and had a lower frequency of iridocyclitis, a higher frequency of symmetric arthritis, a greater cumulative number of joints affected over time, and a different pattern of joint disease, with a greater frequency of shoulder and hip involvement. The strong relationship between the presence of ANA and younger age at disease presentation, asymmetric arthritis, and development of iridocyclitis was confirmed by multivariate regression analysis. CONCLUSION: Our results support the hypothesis that patients with similar characteristics are currently classified into different JIA categories. The value of ANA positivity as a possible modifier of the current classification system deserves consideration.

Antibodies, Antinuclear↗
PubMed2005

Development and validation of a clinical index for assessment of long-term damage in juvenile idiopathic arthritis.

OBJECTIVE: To develop and validate a clinical measure of articular and extraarticular damage in patients with juvenile idiopathic arthritis (JIA). METHODS: The Juvenile Arthritis Damage Index (JADI), which is derived from physical examination and a brief review of the patient's clinical history, is composed of 2 parts: assessments of articular damage (JADI-A) and extraarticular damage (JADI-E). Instrument validation was accomplished by evaluating 158 JIA patients with disease duration of at least 5 years, seen consecutively over 21 months. The instrument's feasibility, face and content validity, construct and discriminative ability, internal consistency, and interrater reliability were examined. RESULTS: Among the 158 JIA patients, 47% and 37% had articular and extraarticular damage, respectively. The JADI was found to be feasible and to possess both face and content validity. The JADI-A score correlated highly with the number of joints with limited range of motion (Spearman's r [r(S)] = 0.72) and correlated moderately with the Childhood Health Assessment Questionnaire score (r(S) = 0.41), Steinbrocker functional classification (r(S) = 0.50), and Poznanski's score of radiographic damage (r(S) = -0.54), thereby demonstrating good construct validity. Correlations with the JADI-E score were lower, owing to the heterogeneity of its items. The JADI-A discriminated well among different levels of disability. The internal consistency (Chronbach's alpha) of the JADI-A and JADI-E was 0.93 and 0.59, respectively. The intraclass correlation coefficients between pairs of independent observers ranged from 0.85 to 0.97. CONCLUSION: The JADI exhibited good reliability, construct validity, and discriminative ability and is therefore a valid instrument for the assessment of long-term damage in patients with JIA, in the context of both clinical management and research settings.

Arthritis, Juvenile↗
PubMed2024

Adeno-Associated Virus Type 5 Infection via PDGFR&#x3b1; Is Associated With Interstitial Lung Disease in Systemic Sclerosis and Generates Composite Peptides and Epitopes Recognized by the Agonistic Immunoglobulins Present in Patients With Systemic Sclerosis.

OBJECTIVE: The etiopathogenesis of systemic sclerosis (SSc) is unknown. Platelet-derived growth factor receptors (PDGFRs) are overexpressed in patients with SSc. Because PDGFR&#x3b1; is targeted by the adeno-associated virus type 5 (AAV5), we investigated whether AAV5 forms a complex with PDGFR&#x3b1; exposing epitopes that may induce the immune responses to the virus-PDGFR&#x3b1; complex. METHODS: The binding of monomeric human PDGFR&#x3b1; to the AAV5 capsid was analyzed by in silico molecular docking, surface plasmon resonance (SPR), and genome editing of the PDGFR&#x3b1; locus. AAV5 was detected in SSc lungs by in situ hybridization, immunohistochemistry, confocal microscopy, and molecular analysis of bronchoalveolar lavage (BAL) fluid. Immune responses to AAV5 and PDGFR&#x3b1; were evaluated by SPR using SSc monoclonal anti-PDGFR&#x3b1; antibodies and immunoaffinity-purified anti-PDGFR&#x3b1; antibodies from sera of patients with SSc. RESULTS: AAV5 was detected in the BAL fluid of 41 of 66 patients with SSc with interstitial lung disease (62.1%) and in 17 of 66 controls (25.75%) (P <&#x2009;0.001). In SSc lungs, AAV5 localized&#x2009;in type II pneumocytes and in interstitial cells. A molecular complex formed of spatially contiguous epitopes of the AAV5 capsid and of PDGFR&#x3b1; was identified and characterized. In silico molecular docking analysis and binding to the agonistic anti-PDGFR&#x3b1; antibodies identified spatially contiguous epitopes derived from PDGFR&#x3b1; and AAV5 that interacted with SSc agonistic antibodies to PDGFR&#x3b1;. These peptides were also able to bind total IgG isolated from patients with SSc, not from healthy controls. CONCLUSION: These data link AVV5 with the immune reactivity to endogenous antigens in SSc and provide a novel element in the pathogenesis of SSc.

Humans↗