Crystal structures of Escherichia coli topoisomerase IV ParE subunit (24 and 43 kilodaltons): a single residue dictates differences in novobiocin potency against topoisomerase IV and DNA gyrase

Topoisomerase IV and DNA gyrase are related bacterial type II topoisomerases that utilize the free energy from ATP hydrolysis to catalyze topological changes in the bacterial genome. The essential function of DNA gyrase is the introduction of negative DNA supercoils into the genome, whereas the essential function of topoisomerase IV is to decatenate daughter chromosomes following replication. Here, we report the crystal structures of a 43-kDa N-terminal fragment of Escherichia coli topoisomerase IV ParE subunit complexed with adenylyl-imidodiphosphate at 2.0-A resolution and a 24-kDa N-terminal fragment of the ParE subunit complexed with novobiocin at 2.1-A resolution. The solved ParE structures are strikingly similar to the known gyrase B (GyrB) subunit structures. We also identified single-position equivalent amino acid residues in ParE (M74) and in GyrB (I78) that, when exchanged, increased the potency of novobiocin against topoisomerase IV by nearly 20-fold (to 12 nM). The corresponding exchange in gyrase (I78 M) yielded a 20-fold decrease in the potency of novobiocin (to 1.0 micro M). These data offer an explanation for the observation that novobiocin is significantly less potent against topoisomerase IV than against DNA gyrase. Additionally, the enzyme kinetic parameters were affected. In gyrase, the ATP K(m) increased approximately 5-fold and the V(max) decreased approximately 30%. In contrast, the topoisomerase IV ATP K(m) decreased by a factor of 6, and the V(max) increased approximately 2-fold from the wild-type values. These data demonstrate that the ParE M74 and GyrB I78 side chains impart opposite effects on the enzyme's substrate affinity and catalytic efficiency.     

Dietary habits in Japanese patients with psoriasis and psoriatic arthritis: Low intake of meat in psoriasis and high intake of vitamin A in psoriatic arthritis

Psoriasis is characterized by T‐helper 17 cell‐dominant abnormal immunity, and hyperproliferation and abnormal differentiation of epidermal keratinocytes. Some patients are associated with arthritis. Dietary habits can modulate the pathogenesis of psoriasis. Previous studies in Western countries showed higher body mass indices, higher intake of fat and lower intake of fish or vegetables in psoriatic patients compared with the reference groups. We evaluated dietary habits in adult Japanese psoriatic patients, using a validated brief‐type self‐administered dietary history questionnaire, and compared the results to those of age‐ and sex‐matched healthy controls. The results in psoriatic patients with arthritis were compared with those in the patients without. Japanese psoriatic patients showed higher body mass indices, higher intake of fish/shellfish, pulses, sugar/sweeteners, vitamin B₁₂ and vitamin D, and lower intake of meat, compared with those of healthy controls. The logistic regression analysis showed that psoriasis was associated with high body mass index and low intake of meat. The intake of confection in patients with high Psoriasis Area and Severity Index was higher than that in those with low index. The intake of β‐carotene, vitamin A and green/yellow vegetables in psoriatic patients with arthritis were higher than those in the patients without. The dietary habits in Japanese psoriatic patients are rather different from those in Western patients. This is the first study showing the differences in dietary habits between psoriatic patients with arthritis and those without. Further studies should elucidate the relationships of these results with skin and joint lesions in psoriatic patients.     

Acute interstitial pneumonia induced by ONO-1078 (pranlukast), a leukotriene receptor antagonist

A 62-year-old woman treated with pranlukast for 2 months developed interstitial pneumonitis with a high fever. A lymphocyte stimulation test was reactive to pranlukast. Her clinical symptoms improved with discontinuation of pranlukast and administration of systemic corticosteroid. To our knowledge, this is the first reported case of drug-induced lung disease involving a leukotriene. The steps that can be taken to promptly reach a diagnosis and to successfully treat this life-threatening condition are described.     

Fibrin deposition and fibrinolysis in the pathogenesis of pulmonary fibrosis

Fibrin deposition is prominent in the course of several forms of pulmonary fibrosis. To elucidate the role of fibrin deposition and fibrinolysis in the process of pulmonary fibrosis, we studied bleomycin-induced fibrosis and the effect of urokinase on it. Beagle dogs were injected intramuscularly 20 times with bleomycin in doses of 2 and 6 mg/kg body weight every other day. Intravenous urokinase treatment was subsequently performed with 3,000 units daily for 40 days and 9,000 units twice daily for 70 days. Histopathologic examination of the lungs of dogs receiving bleomycin alone revealed fibrosis. The lungs of bleomycin-treated dogs which received urokinase had less severe fibrosis and this was confirmed by morphometry with planimetry and the point counting method. Urokinase treatment also diminished the increase of hydroxyproline content of the lung of bleomycin-treated dogs. Decrease of lung tissue fibrinolytic activity assayed by fibrin plate method in bleomycin-treated dogs was also prevented by urokinase. Intravenous urokinase, 24,000 units per day in divided doses, was administered daily in cancer patients with bleomycin treatment. Incidence of pulmonary fibrosis was decreased by urokinase. These data indicate that fibrin deposition and fibrinolysis may have an important influence on the fibrotic process in the lung.     

Toll-like receptor in salivary glands from patients with Sjögren's syndrome: functional analysis by human salivary gland cell line

OBJECTIVE: We investigated expression of toll-like receptor (TLR) in labial salivary glands of patients with Sj?gren's syndrome (SS) and functional TLR expression in the cultured salivary gland cell line. METHODS: Expression of TLR2, TLR3, TLR4, and myeloid differentiation factor 88 (MyD88) in labial salivary glands was examined by immunohistochemistry. Human salivary gland (HSG) cell-line cells were cultured with TLR ligands [peptidoglycan, poly (I:C) and lipopolysaccharide], and CD54 expression and interleukin 6 (IL-6) production was studied. Phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and Akt was examined by Western blotting. Activation of nuclear factor-kappaB (NF-kappaB) p65 in HSG cells was studied by NF-kappaB p65 nuclear translocation by microscopic immunofluorescence or chemiluminescent electrophoretic mobility shift assay and detection of NF-kappaB p65 phosphorylation. RESULTS: TLR2, TLR3, TLR4, and MyD88 were more strongly expressed in the labial salivary glands of SS patients (n =12) than in control subjects (n = 4), and were found in salivary-infiltrating mononuclear cells as well as acinar cells and ductal epithelial cells. In cultured HSG cells, a similar expression pattern was observed, and TLR ligands stimulated CD54 expression and IL-6 production. TLR ligands induced phosphorylation of ERK, JNK, and p38 in HSG cells, but not Akt phosphorylation or activation of NF-kappaB p65. CONCLUSION: Although the putative ligands remain to be determined, our study indicated the activation of the TLR-mediated immune response in SS, and suggested that the TLR effect is mediated through the mitogen-activated protein kinase pathway.     

Risk factors for failure of resolving optic disc pit maculopathy after primary vitrectomy without laser photocoagulation

Japanese Journal of Ophthalmology - To determine factors significantly correlated with the failure of macular reattachment by pars plana vitrectomy (PPV) without laser photocoagulation of the optic...     

Intraoperative optical coherence tomography-assisted displacement of prepapillary membrane in eyes with optic disc pit maculopathy

Graefe's Archive for Clinical and Experimental Ophthalmology - To determine the efficacy of displacing a prepapillary membrane during vitrectomy assisted by intraoperative optical coherence...