Case series of haemothorax secondary to avulsed bullae vessel.

Haemothorax refer to the bleeding in the pleural space. It is commonly due to iatrogenic, blunt or penetrating chest trauma. Non-traumatic haemothorax is a rare entity that can potentially lead to life threatening complications. The initial management of both traumatic and non-traumatic haemothorax includes resuscitation and stabilisation of the patient. We would like to present two cases of non-traumatic haemothorax secondary to an avulsed bullae vessel.

Prevalence of metabolic syndrome in 8-18-year-old school-going children of Srinagar city of Kashmir India.

AIM: Obesity is the most common cause of insulin resistance and metabolic syndrome (MS). These are the most important risk factors for coronary heart disease (CHD). No evidence exists regarding the prevalence of the MS in children in sSrinagar city of Kashmir India. We aimed to evaluate the prevalence of MS in 8-18-year-old school-going children of Kashmir, India. MATERIALS AND METHODS: In this cross-sectional study, 758 respondents in 8-18 years of age were randomly selected using a simple random sampling method. The self-designed questionnaire was individually completed after receiving a written informed consent. The weight, height, waist circumference (WC), body mass index (BMI), and blood pressure were measured using standard tools. Ten milliliters of blood was taken for measuring lipid profile and fasting blood sugar (FBS) of the school children. We determined MS according to the modified Adult Treatment Panel III (ATP III) criteria. RESULTS: The prevalence of the MS was 3.8% (boys: 3.9%, girls: 3.8%) and the prevalence of obesity was 9.9% (boys: 9.9%, girls: 10.6%) among the studied children. Obese subjects had the highest proportion of MS compared with those at risk for overweight and those with normal weight (30.7% vs. 2.5% and 0.5%, respectively; P = 0.000). CONCLUSION: The MS is prevalent even in young children, so we suggest screening programs for children aged 8-18 years to control obesity and MS in the developing world.

Structure of the active core of human stem cell factor and analysis of binding to its receptor kit.

Stem cell factor (SCF) is an early-acting hematopoietic cytokine that elicits multiple biological effects. SCF is dimeric and occurs in soluble and membrane-bound forms. It transduces signals by ligand- mediated dimerization of its receptor, Kit, which is a receptor tyrosine kinase related to the receptors for platelet-derived growth factor (PDGF), macrophage colony-stimulating factor, Flt-3 ligand and vascular endothelial growth factor (VEGF). All of these have extracellular ligand-binding portions composed of immunoglobulin-like repeats. We have determined the crystal structure of selenomethionyl soluble human SCF at 2.2 A resolution by multiwavelength anomalous diffraction phasing. SCF has the characteristic helical cytokine topology, but the structure is unique apart from core portions. The SCF dimer has a symmetric 'head-to-head' association. Using various prior observations, we have located potential Kit-binding sites on the SCF dimer. A superimposition of this dimer onto VEGF in its complex with the receptor Flt-1 places the binding sites on SCF in positions of topographical and electrostatic complementarity with the Kit counterparts of Flt-1, and a similar model can be made for the complex of PDGF with its receptor.

Engineering a soluble extracellular erythropoietin receptor (EPObp) in Pichia pastoris to eliminate microheterogeneity, and its complex with erythropoietin.

The extracellular ligand-binding domain (EPObp) of the human EPO receptor (EPOR) was expressed both in CHO (Chinese Hamster Ovary) cells and in Pichia pastoris. The CHO and yeast expressed receptors showed identical affinity for EPO binding. Expression levels in P. pastoris were significantly higher, favoring its use as an expression and scale-up production system. Incubation of EPO with a fourfold molar excess of receptor at high protein concentrations yielded stable EPO-EPObp complexes. Quantification of EPO and EPObp in the complex yielded a molar ratio of one EPO molecule to two receptor molecules. Residues that are responsible for EPOR glycosylation and isomerization in Pichia were identified and eliminated by site-specific mutagenesis. A thiol modification was identified and a method was developed to remove the modified species from EPObp. EPObp was complexed with erythropoietin (EPO) and purified. The complex crystallized in two crystal forms that diffracted to 2.8 and 1.9 A respectively. (Form 1 and form 2 crystals were independently obtained at AxyS Pharmaceuticals, Inc. and Amgen, Inc. respectively.) Both contained one complex per asymmetric unit with a stoichiometry of two EPObps to one EPO.

NMR structure of human erythropoietin and a comparison with its receptor bound conformation.

The solution structure of human erythropoietin (EPO) has been determined by nuclear magnetic resonance spectroscopy and the overall topology of the protein is revealed as a novel combination of features taken from both the long-chain and short-chain families of hematopoietic growth factors. Using the structure and data from mutagenesis studies we have elucidated the key physiochemical properties defining each of the two receptor binding sites on the EPO protein. A comparison of the NMR structure of the free EPO ligand to the receptor bound form, determined by X-ray crystallography, reveals conformational changes that may accompany receptor binding.

Efficiency of signalling through cytokine receptors depends critically on receptor orientation.

Human erythropoietin is a haematopoietic cytokine required for the differentiation and proliferation of precursor cells into red blood cells. It activates cells by binding and orientating two cell-surface erythropoietin receptors (EPORs) which trigger an intracellular phosphorylation cascade. The half-maximal response in a cellular proliferation assay is evoked at an erythropoietin concentration of 10 pM, 10(-2) of its Kd value for erythropoietin-EPOR binding site 1 (Kd approximately equal to nM), and 10(-5) of the Kd for erythropoietin-EPOR binding site 2 (Kd approximately equal to 1 microM). Overall half-maximal binding (IC50) of cell-surface receptors is produced with approximately 0.18 nM erythropoietin, indicating that only approximately 6% of the receptors would be bound in the presence of 10 pM erythropoietin. Other effective erythropoietin-mimetic ligands that dimerize receptors can evoke the same cellular responses but much less efficiently, requiring concentrations close to their Kd values (approximately 0.1 microM). The crystal structure of erythropoietin complexed to the extracellular ligand-binding domains of the erythropoietin receptor, determined at 1.9 A from two crystal forms, shows that erythropoietin imposes a unique 120 degrees angular relationship and orientation that is responsible for optimal signalling through intracellular kinase pathways.