Clinical associations of autoantibodies to a p155/140 kDa doublet protein in juvenile dermatomyositis.

OBJECTIVES: Myositis-specific autoantibodies (MSAs) may define homogeneous clinical subsets of adult patients with dermatomyositis (DM). Recently, there have been descriptions of novel autoantibodies in DM. This study was conducted to establish the clinical significance of anti-p155/140 autoantibodies in juvenile DM (JDM). METHODS: The first 116 children recruited to the JDM National Registry and Repository (UK and Ireland) were studied. Comprehensive clinical features were recorded and sera screened for anti-p155/140 autoantibodies using radio-immunoprecipitation. Sera from adults with DM (n = 20), PM (n = 25), SSc (n = 150), SLE (n = 40) and healthy subjects (n = 50) were used for comparison. Immunodepletion experiments were used to establish whether the p155/140 kDa targets recognized by JDM sera were the same as adult DM sera. RESULTS: Twenty-seven out of 116 (23%) JDM cases were positive for anti-p155/140 in comparison with 6/20 (30%) adults with DM. Immunodepletion confirmed that the 155/140 kDa proteins recognized by JDM and adult DM sera were the same targets. All other adult control sera were negative for anti-p155/140 autoantibodies. There was a higher frequency of males in the anti-p155/140-positive JDM group (P = 0.02). JDM patients with anti-p155/140 autoantibodies had significantly more cutaneous involvement including Gottron's papules (P = 0.003), ulceration (P = 0.005) and oedema (P = 0.013). The distribution of skin lesions was more extensive particularly periorbitally (P = 0.014) and over the small (P < 0.001) and large joints (P = 0.003). CONCLUSIONS: Anti-p155/140 autoantibodies are clinically significant in JDM and may define a clinical subset in terms of disease severity and outcome. The same autoantigen target is detected in adult DM patients.

HLA class II haplotype and autoantibody associations in children with juvenile dermatomyositis and juvenile dermatomyositis-scleroderma overlap.

OBJECTIVES: To investigate a large cohort of children with juvenile dermatomyositis (JDM), and those with JDM-scleroderma (JDM-SSc) overlap, using detailed serological analysis, HLA class II genotyping and clinical characterization. METHODS: Children (114) with JDM were recruited, and clinical data collected, through the JDM National Registry and Repository (UK and Ireland). Sera were assayed for ANA using standard immunofluorescence techniques and specific antibodies characterized using ELISA, immunodiffusion and radioimmunoprecipitation. Patients and controls (n = 537) were genotyped at the HLA-DRB1 and DQB1 loci, and then the DQA1 locus data was derived. RESULTS: Over 70% of the patients were ANA-positive. Clear differences in serological and genetic data were demonstrated between JDM and JDM-SSc overlap groups. Strong associations were seen for HLA-DRB1*03 (all cases vs controls, P(corr) = 0.02; JDM-SSc vs controls, P(corr) = 0.001) and HLA-DQA1*05 (all cases vs controls, P(corr) = 0.01; JDM-SSc vs controls, P(corr) = 0.005). The frequency of the HLA-DRB1*03-DQA1*05-DQB1*02 haplotype was significantly increased in the JDM-SSc (P = 0.003) and anti-PM-Scl antibody (P = 0.002) positive groups. All anti-U1-RNP antibody-positive patients had at least one copy of HLA-DRB1*04-DQA1*03-DQB1*03 haplotype. Associations were observed between serology and specific clinical features. CONCLUSIONS: We present clinical data, HLA genotyping and serological profiling on a large cohort of JDM patients and a carefully characterized subset of patients with JDM-SSc overlap. The results confirm known HLA associations and extend the knowledge by stratification of data in serological and clinical subgroups. In the future, a combination of serological and genetic typing may allow for better prediction of clinical course and disease subtype in JDM.

Signalling functions of protein palmitoylation.

Covalent lipid modifications anchor numerous signalling proteins to the cytoplasmic face of the plasma membrane. These modifications mediate protein-membrane and protein-protein interactions and are often essential for function. Protein palmitoylation, due to its reversible nature, may be particularly important for modulating protein function during cycles of activation and deactivation. Despite intense investigation, the exact functions of protein palmitoylation are not well understood. However, it is clear that palmitoylation can affect a protein's affinity for membranes, subcellular localization, and interactions with other proteins. In this review, recent advances in understanding the functions and mechanisms of protein palmitoylation are discussed, with particular emphasis on how this lipid affects the biochemistry and cell biology of signalling proteins.

Differential effects of acyl-CoA binding protein on enzymatic and non-enzymatic thioacylation of protein and peptide substrates.

Both enzymatic and autocatalytic mechanisms have been proposed to account for protein thioacylation (commonly known as palmitoylation). Acyl-CoA binding proteins (ACBP) strongly suppress non-enzymatic thioacylation of cysteinyl-containing peptides by long-chain acyl-CoAs. At physiological concentrations of ACBP, acyl-CoAs, and membrane lipids, the rate of spontaneous acylation is expected to be too slow to contribute significantly to thioacylation of signaling proteins in mammalian cells (Leventis et al., Biochemistry 36 (1997) 5546-5553). Here we characterized the effects of ACBP on enzymatic thioacylation. A protein S-acyltransferase activity previously characterized using G-protein alpha-subunits as a substrate (Dunphy et al., J. Biol. Chem., 271 (1996) 7154-7159), was capable of thioacylating short lipid-modified cysteinyl-containing peptides. The minimum requirements for substrate recognition were a free cysteine thiol adjacent to a hydrophobic lipid anchor, either myristate or farnesyl isoprenoid. PAT activity displayed specificity for the acyl donor, efficiently utilizing long-chain acyl-CoAs, but not free fatty acid or S-palmitoyl-N-acetylcysteamine. ACBP only modestly inhibited enzymatic thioacylation of a myristoylated peptide or G-protein alpha-subunits under conditions where non-enzymatic thioacylation was reduced to background. Thus, protein S-acyltransferase remains active in the presence of physiological concentrations of ACBP and acyl-CoA in vitro and is likely to represent the predominant mechanism of thioacylation in vivo.

Tissue distribution of rat glucagon receptor and GLP-1 receptor gene expression.

The regulation of glucose metabolism by glucagon and GLP-1 is well established, but novel functions for these and other proglucagon-derived peptides are less well defined. This paper highlights the diversity of both GLP-1 and glucagon activity by studying the tissue distribution of glucagon and GLP-1 receptor gene expression by both Southern blot analysis of RT-PCR products and nuclease protection assays. By Southern blot analysis of RT-PCR products, GLP-1 receptor mRNA was detected in lung, hypothalamus, hippocampus, cerebral cortex, kidney, pancreas, and throughout the gastrointestinal tract. Glucagon receptor expression was detected in liver, kidney, spleen, thymus, adrenal glands, pancreas, cerebral cortex, lung, and throughout the gastrointestinal tract. Nuclease protection assay revealed glucagon receptor expression to be highest in liver and kidney, whereas GLP-1 receptor expression was only detected by protection assay in lung, stomach, and large bowel. Despite previous evidence that other receptors for proglucagon-derived peptides may exist, no evidence of novel receptors or multiple isoforms of the glucagon and GLP-1 receptors was found, indicating that the two cloned receptors may mediate all the effects of proglucagon-derived peptides, or that novel receptors may share less homology with the glucagon and GLP-1 receptors than previously anticipated.

Significance of lymph node metastasis in differentiated thyroid cancer.

In age-matched patients with differentiated carcinoma of the thyroid, the tumor recurred in 32 per cent of those with lymph node metastases and in 14 per cent of those without lymph node metastases. Twenty-four per cent of patients with nodal involvement at the initial examination died of thyroid cancer, whereas only 8 per cent of those without nodal involvement died of thyroid cancer. In patients less than forty years old, there were no deaths in those without nodal metastases bu there were three deaths (11 per cent) in patients with nodal metastases. In patients more than forty years old, nine (41 per cent) iwth nodal metastases died of tumor, and four (15 per cent) without nodal metastases died of tumor. In the presence of positive nodes the death rate was substantially greater in the older than in the younger patients. Nodal involvement has an adverse effect on prognosis, but appears to be less important than the age of the patient.

Pancreatic tumor of mesenchymal origin presenting as obstructive jaundice.

A case of an unusual tumor occurring in the head of the pancreas is presented. Definitive diagnosis could not be made, the lesion being either a low grade myxofibrosarcoma or a benign fibrous histiocytoma. The literature is discussed and several cases believed to be pancreatic sarcomata are presented, only one of which was definitely of pancreatic origin. No other case of fibrous histiocytoma of the pancreas has been reported.

Isolation, characterisation and expression of mRNAs encoding the ovine CC chemokines, monocyte chemoattractant protein (MCP)-1alpha and -2.

CC chemokines are important mediators of immune responses, orchestrating the differential recruitment of various leukocyte populations. Despite the large number of known CC chemokines in other species, no cDNA encoding ovine CC chemokines have been isolated. A homology cloning strategy was utilised to isolate the cDNA of ovine CC chemokines. Full-length monocyte chemoattractant protein (MCP)-1alpha and -2 cDNA have been isolated. The predicted ovine MCP-1alpha amino acid sequence shares 87 and 75% identity with bovine MCP-1alpha and porcine MCP-1, respectively. The predicted ovine MCP-2 amino acid sequence shares 92 and 85% identity with bovine and porcine MCP-2, respectively. Northern blot analysis of MCP-1alpha revealed that it is strongly expressed in cells isolated from mammary lavage fluid (MAL) of ewes given intramammary infusions of Haemonchus contortus. Weak signals were detected in mammary and abomasal tissue. Southern blot analysis of reverse transcriptase-polymerase chain reaction (RT-PCR) products indicates that MCP-1alpha mRNA levels increase in abomasum after challenge with H. contortus. MCP-1alpha mRNA levels were also increased in bronchoalveolar lavage (BAL) cells and lung tissue after house dust mite extract (HDME) challenge. Similarly, MCP-2 mRNA was detected by Northern blot analysis at high levels in MAL cells after H. contortus intramammary infusion, and increased in BAL cells and lung tissue in HDME-challenged sheep. MCP-2 mRNA was not detected by Northern blots in whole mammary or abomasal tissue, but Southern blot analysis of RT-PCR products also indicates that MCP-2 mRNA increases in abomasal tissue after challenge with H. contortus. Hence, two ovine CC chemokine mRNA have been isolated that are up-regulated in response to parasite infection and allergen challenge. Ultimately the isolation of these and other ovine CC chemokines will help elucidate a wide variety of immune responses in sheep.

Thin-layer chromatography/liquid secondary ion mass spectrometry in the determination of major bile salts in dog bile.

Positive and negative ion liquid-state secondary-ion mass spectrometry (LSIMS) was applied to several bile acids and bile salts and their spectra were measured directly from the surface of silica gel thin-layer chromatograms. Such spectra were identical to the LSIMS spectra of the pure compound at the same concentration. Three-dimensional ion images were obtained of a model mixture of cholic, chenodeoxycholic and lithocholic acids in both the positive and negative ion modes. A sample of dog bile was prepared, and the bile acids extracted from it were separated by high-performance TLC; TLC/LSIMS spectra were obtained for sodium taurocholate and sodium taurochenodeoxycholate/taurodeoxycholate, the predominant bile salts present. Quantitative estimates of the analytes were obtained by monitoring the ion intensity for the sample spot and a standard spot that had been developed in parallel on the same TLC plate. The concentration of sodium taurocholate in the bile of this particular dog was found to be 38 mg/ml.