SHARPIN forms a linear ubiquitin ligase complex regulating NF-κB activity and apoptosis

SHARPIN is a ubiquitin-binding and ubiquitin-like-domain-containing protein which, when mutated in mice, results in immune system disorders and multi-organ inflammation. Here we report that SHARPIN functions as a novel component of the linear ubiquitin chain assembly complex (LUBAC) and that the absence of SHARPIN causes dysregulation of NF-κB and apoptotic signalling pathways, explaining the severe phenotypes displayed by chronic proliferative dermatitis (cpdm) in SHARPIN-deficient mice. Upon binding to the LUBAC subunit HOIP (also known as RNF31), SHARPIN stimulates the formation of linear ubiquitin chains in vitro and in vivo. Coexpression of SHARPIN and HOIP promotes linear ubiquitination of NEMO (also known as IKBKG), an adaptor of the IκB kinases (IKKs) and subsequent activation of NF-κB signalling, whereas SHARPIN deficiency in mice causes an impaired activation of the IKK complex and NF-κB in B cells, macrophages and mouse embryonic fibroblasts (MEFs). This effect is further enhanced upon concurrent downregulation of HOIL-1L (also known as RBCK1), another HOIP-binding component of LUBAC. In addition, SHARPIN deficiency leads to rapid cell death upon tumour-necrosis factor α (TNF-α) stimulation via FADD- and caspase-8-dependent pathways. SHARPIN thus activates NF-κB and inhibits apoptosis via distinct pathways in vivo.

Lung cancer statistics in Luxembourg from 1981 to 2008

Lung cancer is the leading cause of cancer-related death in the world and in Luxembourg. As a part of "The health science initiative focused on personalized medicine", Luxembourg aims to participate by developing diagnostics to improve the detection and treatment of lung cancer. In line with this objective, this study made a review of evolution of lung cancer in Luxembourg from 1981 to 2008 and compared this statistics to the situation in the Nordic countries, Europe in general and the World. Incidence data of the national morphological tumour registry and mortality data of the service of statistics of the national ministry of health is depicted in charts with trend lines, in the framework of a statistical evaluation of relevant parameters. The data indicate that while male lung cancer incidence decreased in Luxembourg, the incidence in women and its mortality have doubled over the 28-year span considered. Notwithstanding this increase, the female lung cancer incidence and mortality remain low compared to the Nordic countries and Europe. Interestingly, the study also potentially suggests that the lung cancer pattern follows the smoking pattern in incidence and mortality.

Structure of the archaeal Na+/H+ antiporter NhaP1 and functional role of transmembrane helix 1

We have determined the structure of the archaeal sodium/proton antiporter NhaP1 at 7 Å resolution by electron crystallography of 2D crystals. NhaP1 is a dimer in the membrane, with 13 membrane-spanning α-helices per protomer, whereas the distantly related bacterial NhaA has 12. Dimer contacts in the two antiporters are very different, but the structure of a six-helix bundle at the tip of the protomer is conserved. The six-helix bundle of NhaA contains two partially unwound α-helices thought to harbour the ion-translocation site, which is thus similar in NhaP1. A model of NhaP1 based on detailed sequence comparison and the NhaA structure was fitted to the 7 Å map. The additional N-terminal helix 1 of NhaP1, which appears to be an uncleaved signal sequence, is located near the dimer interface. Similar sequences are present in many eukaryotic homologues of NhaP1, including NHE1. Although fully folded and able to dimerize, NhaP1 constructs without helix 1 are inactive. Possible reasons are investigated and discussed.

Structural and functional abnormalities in lungs in patients with achalasia

Dilatation and oesophageal body aperistalsis in achalasia can lead to stasis which in turn can induce repeated microaspiration. It is therefore conceivable that patients with achalasia may also have abnormalities in lungs secondary to repeated episodes of microaspiration. There is a lack of systematic study on involvement of lungs in patients with achalasia. Thirty patients with achalasia underwent pulmonary function tests (spirometry, and carbon mono-oxide diffusion capacity) and high resolution computerized tomography (HRCT) of the chest. The mean age of patients and mean duration of disease were 33.5 +/- 10.9 years and 28.1 +/- 27.3 months respectively. Regurgitation was present in 22 (73.3%) of them. Respiratory symptoms in them were dry cough in 17 (56.6%), and chest pain in 18 (60%). The oesophagus was dilated in 26 (86.6%) and 13 (43.3%) had residue in oesophagus. Sixteen (53.3%) patients had either anatomical changes as seen on HRCT or functional changes as observed on pulmonary function tests. Of those with functional abnormalities, five (16.6%) and one (3.3%) had restrictive and obstructive airways disease respectively. While evidence of tracheo-bronchial compression by dilated oesophagus was present in eight (26.6%), 10 (33.3%) patients had parenchymal lung disease [nodular opacities in five (16.6%), ground glass appearance six (20%), patchy pulmonary fibrosis five (16.6%), air trapping two (6.6%), consolidation and bronchiectasis one (3.3%) each]. There was a significant association between presence of regurgitation and dilatation of oesophagus (P = 0.032). More than half (53.3%) of patients with achalasia have structural and/or functional abnormalities in lungs.

Klebsiella meningitis. A case report

Acute bacterial meningitis is a severe CNS infection occurring mostly in infants and older children. Bacterial meningitis caused by gram-negative bacteria is usually fatal. Klebsiella pneumoniae is an uncommon gram-negative bacteria causing meningitis with a poor outcome. Though the commonest presentation of bacterial meningitis is fever, patients usually seek medical attention for uncontrolled seizure and features of raised ICP. The commonest complications of gram-negative bacterial meningitis including Klebsiella meningitis are subdural hygroma / empyema, hydrocephalus, infarcts (both arterial and venous) and cortical blindness due to hypoxic ischaemic insult. MRI is the best modality for evaluating these patients for early diagnosis. Early institution of treatment significantly reduces the mortality and morbidity. We describe a case of acute bacterial meningitis caused by Klebsiella pneumoniae with MR evidence of sinus thrombosis, venous infarcts and subdural hygroma.

Chronic Tuberculous Retropharyngeal Abscess Due to Vertebral Tuberculosis with Associated Calvarial Tuberculosis

The occurrence of chronic tuberculous retropharyngeal abscess and calvarial tuberculosis is rare, even in isolated form. Chronic tuberculous retropharyngeal abscess is usually due to vertebral tuberculosis in adults. Calvarial tuberculosis is a rare manifestation of extra-pulmonary tuberculosis with limited reports in medical literature. We describe a rare case of chronic tuberculous retropharyngeal abscess due to vertebral tuberculosis with associated calvarial tuberculosis.

The autoantibody rheumatoid factor may be an independent risk factor for ischaemic heart disease in men

BACKGROUND

Subjects with rheumatoid arthritis have an increased prevalence of ischaemic heart disease (IHD). This is most likely in those people with the autoantibody rheumatoid factor (RF). RF is strongly associated with rheumatoid arthritis (RA) but is also present in up to 15% of all adults.

OBJECTIVE

To determine whether RF might identify people in a general population who also share an increased likelihood of developing IHD.

METHODS

Subjects from the Hertfordshire Cohort Study were investigated for the presence of RF. Subjects completed a questionnaire and attended a clinic where a history of IHD was recorded (ECG, coronary artery bypass grafting, Rose chest pain). Associations between the presence of RF, antinuclear antibodies (ANA), anticardiolipin antibodies (ACA) and IHD in 567 men and 589 women were investigated and compared with traditional risk factors for IHD.

RESULTS

RF was associated with an increased likelihood of IHD in men (odds ratio (OR) = 3.1, 95% CI 1.7 to 5.4, p<0.001). This increased risk could not be explained by traditional risk factors for IHD (mutually adjusted OR for RF 2.9 (95% CI 1.6 to 5.3), p<0.001). There was no significant association between RF in women or between ANA or ACA with IHD in men or women.

CONCLUSION

This work suggests that RF is an independent risk factor for IHD in the general population. It lends support to the importance of inflammation in atherosclerosis and suggests that autoimmune processes may be involved. In addition, it raises the intriguing possibility that RF may have a direct role in the pathogenesis of IHD in some subjects.

Detecting molecular interactions that stabilize, activate and guide ligand-binding of the sodium/proton antiporter MjNhaP1 from Methanococcus jannaschii

Integral membrane proteins are involved in virtually every cellular process. Precisely regulating these machineries would allow controlling many human and vertebrate diseases. Embedded into cellular membranes, membrane proteins establish molecular interactions that sensitively react to environmental changes and to molecular compounds, such as ligands or inhibitors. We applied atomic force microscopy (AFM) to image the Na(+)/H(+) antiporter MjNhaP1 from Methanococcus jannaschii, and single-molecule force spectroscopy (SMFS) to probe molecular interactions that drive the protein structure-function relationship. High-resolution AFM topographs showed the dimeric assembly of MjNhaP1 being reconstituted into a lipid bilayer. SMFS of MjNhaP1 unraveled molecular interactions stabilizing individual structural domains. Transmembrane domains exhibited certain probabilities to unfold individually or cooperatively with other domains resulting in different unfolding pathways. Helices VIII and X established pH sensitive interactions altering significantly upon MjNhaP1 activation, while removal of the ligand (Na(+)) destabilized the entire antiporter except helix VIII. It is assumed that Asp234/235 of helix VIII are involved in the ligand-binding site and that helix X plays a functional role in the activation of the transporter.

Pyomyositis: a diagnostic problem

A case of a 45-year-old lady presenting with symptoms suggestive of pancreatitis is described. Initially the findings on Imaging were ambiguous while the enzyme studies were against the diagnosis of pancreatitis. Recurrence of symptoms and with Increased intensity prompted repeated imaging and further investigations. Finally, by a combination of CT scan, MR imaging and muscle biopsy the rare diagnosis of pyomyositis was established. The fact that this case was difficult to diagnose because of its rarity and its mimicking pencreatitis is discussed.

Structure of the monomeric outer-membrane porin OmpG in the open and closed conformation

OmpG, a monomeric pore-forming protein from Escherichia coli outer membranes, was refolded from inclusion bodies and crystallized in two different conformations. The OmpG channel is a 14-stranded beta-barrel, with short periplasmic turns and seven extracellular loops. Crystals grown at neutral pH show the channel in the open state at 2.3 A resolution. In the 2.7 A structure of crystals grown at pH 5.6, the pore is blocked by loop 6, which folds across the channel. The rearrangement of loop 6 appears to be triggered by a pair of histidine residues, which repel one another at acidic pH, resulting in the breakage of neighbouring H-bonds and a lengthening of loop 6 from 10 to 17 residues. A total of 151 ordered LDAO detergent molecules were found in the 2.3 A structure, mostly on the hydrophobic outer surface of OmpG, mimicking the outer membrane lipid bilayer, with three LDAO molecules in the open pore. In the 2.7 A structure, OmpG binds one OG and one glucose molecule as sugar substrates in the closed pore.

Growth and infectious exposure during infancy and the risk of rheumatoid factor in adult life

BACKGROUND

The contribution of the environment to rheumatoid arthritis (RA) remains uncertain. Intrauterine and early postnatal life may be important. Rheumatoid factor (RF) found in around 10% of the normal population confers a risk of developing RA and may be present years before onset of clinical disease. The immune pathology leading to RA and RF may have similar genetic and environmental influences.

OBJECTIVE

To measure RF in people for whom data on birth weight, infant growth, and markers of infectious exposure during infancy and childhood, had been previously recorded.

METHODS

675 men and 668 women aged 59-67 years, born and still resident in Hertfordshire, UK, were studied. RF was measured with an ELISA. Associations between presence of RF, early growth, and markers of hygiene in infancy, were investigated.

RESULTS

RF was detected in 112/675 (16.6%) men and 79/668 (11.8%) women. No significant relationships existed between early growth and presence of RF in men or women. Among women, sharing a bedroom during childhood was associated with a lower risk of RF positivity (OR = 0.48, 95% CI 0.30 to 0.78, p = 0.003).

CONCLUSIONS

A developing immune system exposed to increased infectious exposure is less likely to produce RF in adult life; this may reduce the pathological process which leads to RA.

A case of disseminated hydatidosis

A young lady initially found to have hydatid cysts in the lung only, subsequently within a very short period was found to develop cysts in the liver. Soon after, she developed cysts in the subcutaneous tissue over the anterolateral chest wall, which, on investigation, revealed hepatic cysts herniating through the chest wall defects caused by previous operations. The unique features of this case include the degree of dissemination, the multiplicity of sites and the peculiar nature of herniation of the hepatic cysts into the parietes.