Peptide analysis,stability studies,and structural modeling explain contradictory peptide motifs and unique properties of the NOD mouse MHC class II molecule H2-A(g7)

The MHC class II molecule H2-A(g7) is the chief genetic determinant in insulin-dependent diabetes mellitus of the non-obese diabetic (NOD) mice. Poor peptide binding ability, as well as presentation of a unique subset of peptides by this molecule was suggested to promote autoimmunity in this strain. However, several laboratories have presented results in favor of an H2-A(g7) molecule that can avidly bind many different peptides. The crystal structures of H2-A(g7) in complex with two different peptides did not completely resolve this issue. To analyze the peptide binding capacity and the motif requirements of H2-A(g7), we eluted natural ligands from purified H2-A(g7) molecules isolated from the H2-A(g7)-transfected M12-C3 cells. A low peptide yield dominated by a few peptide ligands was found. Pool sequencing and alignment of individual ligands on the basis of molecular modeling revealed a peptide-binding motif with basic/aliphatic/small hydrophilic amino acids at relative position 1 (p1), aliphatic amino acids at p4, Ala at p6, and acidic amino acids and Ser/Gly at p9, as well as acidic residues at p10/11. Though weak, the binding of individual ligands, as well as the importance of an acidic C-terminal residue was confirmed by peptide binding studies to isolated H2-A(g7) molecules. Furthermore, the H2-A(g7) molecule incompletely dissociated into its constituent chains in SDS-electrophoresis under nonreducing conditions. This provides additional evidence of its weak affinity for peptides, which probably arises from the combination of beta56His/beta57Ser/beta78Ala and other unique H2-A(g7) residues in contact with the antigenic peptide. These results allow a better understanding of the role of this molecule in the development of autoimmunity and the identification of epitopes relevant to diabetes.     

Study of the carrying angle of the human elbow joint in full extension: a morphometric analysis

This study measured the carrying angle of the elbow joint in full extension in 600 students, using the supplementary angle to that between the longitudinal axis of the arm and that of the forearm. The mean carrying angle was 12.88°±5.92: 10.97°±4.27 in men and 15.07°±4.95 in women. The carrying angle changes with skeletal growth and maturity. The angle is always greater on the side of the dominant hand. We confirmed the inverse relationship between the carrying angle and the intertrochanteric diameter. Also, the type of constitution influences the value of the carrying angle, especially in women.     

Adamantinoma of tibia: a case of late local recurrence along with lung metastases

Adamantinomas of long bones are rare primary low-grade malignant tumours composed of cells with epithelial and fibrous characteristics. Local recurrence, though scarce, occurs 5-15 years after the onset of diagnosis. We report a case of local recurrence of an adamantinoma localised in tibia, along with the presence of two lung metastases, 24 years after diagnosis and surgical therapy of the primary tumour. The local recurrence and the lung metastases were removed surgically. The patient remains free of the disease for 3 years.     

Expression of costimulatory molecules in peripheral blood mononuclear cells of atopic asthmatic children during virus-induced asthma exacerbations

BACKGROUND: Respiratory viruses are the most frequent triggers of acute asthma exacerbations. Herein we investigate costimulatory molecule expression on peripheral blood mononuclear cells (PBMC) during such exacerbations. METHODS: Eleven children with atopic asthma were followed prospectively and respiratory symptoms were recorded on diary cards. A blood sample and nasopharyngeal wash (NPW) were obtained at baseline and subsequently during an exacerbation. PBMC were immunophenotyped using flow cytometry. NPW samples were examined for the presence of respiratory viruses by RT-PCR. RESULTS: A virus was detected in 73% of exacerbations and none at baseline. A drop of NK cells and a marginal increase of monocytes were the only changes of cell count during the exacerbation. A significant downregulation of B7-2 on NK cells and of B7-1 on monocytes was also observed during exacerbations. CONCLUSIONS: The above observations are in contrast to in vitro findings showing an upregulation of costimulatory molecules after exposure of blood cells to viruses or allergens. It is possible that activated immune cells leave the blood stream to migrate to the inflammation site during acute asthma exacerbations.     

Inhibition of C5 or absence of C6 protects from sepsis mortality

Inhibiting complement anaphlytoxin C5a during sepsis may prevent sepsis mortality. Although human anti-C5 antibodies exist, their therapeutic use in microbial sepsis has been avoided because of the hypothesis that inhibiting C5b will prevent formation of the bactericidal membrane attack complex (MAC) and worsen clinical outcome. We wished to test the hypothesis that inhibition of C5 would improve outcomes in sepsis. Sepsis was induced in rats by laparotomy and cecal ligation and puncture (CLP) by an IACUC-approved protocol. Sham animals underwent laparotomy without CLP. Following CLP rats were randomized to receive a single IV dose of purified IgG ant-C5 antibody (Ab) or control IgG Ab. Anti-C5 Ab treated rats (n = 20) had significantly lower mortality vs. controls (n = 21), 20% vs. 52% (P = 0.019, log-rank). Analysis of bacterial load by culture of spleen and liver homogenates showed a reduction in colony forming units in anti-C5 Ab treated rats vs. control IgG (P = 0.003 and 0.009, respectively). Anti-C5 treatment reduced lung injury as measured by total MPO content of lung tissue (P = 0.024). Finally, rats genetically deficient in C6 production, unable to form MAC but capable of producing C5a and C5b, were protected from CLP-induced sepsis mortality. Our results show that in anti-C5 antibody therapy prevents CLP sepsis-induced mortality and improves lung injury. Inhibition of the complement MAC does not increase bacterial load or mortality, therefore, the use of anti-C5 therapy may be beneficial rather than detrimental in sepsis.     

Deletion of the mental retardation gene Gdi1 impairs associative memory and alters social behavior in mice

Non-specific mental retardation (NSMR) is a common human disorder characterized by mental handicap as the only clinical symptom. Among the recently identified MR genes is GDI1, which encodes alpha Gdi, one of the proteins controlling the activity of the small GTPases of the Rab family in vesicle fusion and intracellular trafficking. We report the cognitive and behavioral characterization of mice carrying a deletion of Gdi1. The Gdi1-deficient mice are fertile and anatomically normal. They appear normal also in many tasks to assess spatial and episodic memory and emotional behavior. Gdi1-deficient mice are impaired in tasks requiring formation of short-term temporal associations, suggesting a defect in short-term memory. In addition, they show lowered aggression and altered social behavior. In mice, as in humans, lack of Gdi1 spares most central nervous system functions and preferentially impairs only a few forebrain functions required to form temporal associations. The general similarity to human mental retardation is striking, and suggests that the Gdi1 mutants may provide insights into the human defect and into the molecular mechanisms important for development of cognitive functions.     

Detection of sheep poxvirus in skin biopsy samples by a multiplex polymerase chain reaction

The development of a multiplex polymerase chain reaction (PCR) method with amplification of capripoxvirus in a single-step procedure from skin biopsies using three primer pairs, two specific for capripoxvirus and one specific for alpha-tubulin is described. A sensitive multiplex PCR was achieved by optimization of parameters such as the primer concentrations, magnesium and dNTPs concentrations. False negative results that sometimes arise due to inhibitors of DNA amplification may be avoided by the inclusion in the assay of alpha-tubulin primers. The results reported on 42 skin biopsies from sheep suspected to have poxvirus infection, indicated that the assay could monitor simultaneously DNA extraction from skin biopsy samples and allow improved detection of capripoxvirus within 24 h of specimen receipt in the laboratory.     

Postoperative prognosis of pulmonary adenocarcinoma subtypes correlates with HLA-DR expression and the number of tumor-infiltrating cells

Human pulmonary adenocarcinomas (AC) can be divided into two types with special morphologic and immunohistologic properties and a different number of tumor-infiltrating cells as shown by previous investigations. In the present study the relevance of this subdivision for patients' survival was investigated. 42 surgically resected pulmonary AC of stage I and II were subclassified using light and electron microscope. For immunohistologic phenotypization, reactions with monoclonal antibodies against HLA-DR, CD1 and CD3 were studied on fresh tumor specimens. Postoperative survival was evaluated after at least 24 months. AC of type I (N=23) with mucin production and ultrastructural properties of goblet cells showed almost no HLA-DR expression. Infiltration by CD1-positive dendritic cells Langerhans cells and CD3-positive T lymphocytes was significantly lower than in AC of type II (N=19), which expressed HLA-DR homogeneously and showed, ultrastructurally, Clara cell and/or type II pneumocyte properties. Patients' outcome was similar in stage I AC of both types: about 70% of patients were still alive after 24 months. However, significant differences were found between the two types in stage II AC with regional lymph node metastases: survival of patients with AC of type II corresponded roughly with stage I tumors (67%) but only 20% of patients with type I AC were still alive after 24 months. These results indicate that postoperative prognosis for patients with pulmonary AC of type II is more favourable than for mucinous AC of type I. This may be due to the homogeneous HLA-DR expression and higher number of immunologically competent tumor-infiltrating cells which possibly results in better tumor surveillance.