The cyclooxygenases

Cyclooxygenases (COXs) catalyze the rate-limiting step in the production of prostaglandins, bioactive compounds involved in processes such as fever and sensitivity to pain, and are the target of aspirin-like drugs. COX genes have been cloned from coral, tunicates and vertebrates, and in all the phyla where they are found, there are two genes encoding two COX isoenzymes; it is unclear whether these genes arose from an early single duplication event or from multiple independent duplications in evolution. The intron-exon arrangement of COX genes is completely conserved in vertebrates and mostly conserved in all species. Exon boundaries largely define the four functional domains of the encoded protein: the amino-terminal hydrophobic signal peptide, the dimerization domain, the membrane-binding domain, and the catalytic domain. The catalytic domain of each enzyme contains distinct peroxidase and cyclooxygenase active sites; COXs are classified as members of the myeloperoxidase family. All COXs are homodimers and monotopic membrane proteins (inserted into only one leaflet of the membrane), and they appear to be targeted to the lumenal membrane of the endoplasmic reticulum, where they are N-glycosylated. In mammals, the two COX genes encode a constitutive isoenzyme (COX-1) and an inducible isoenzyme (COX-2); both are of significant pharmacological importance.     

'Navius' kissing stents for coronary bifurcation stenosis,recreating a new metallic carina: an IVUS-assessed case report

We report a case of implantation of a new design of stent which allows creation of a double-hemispheric lumen for the treatment of a bifurcational stenosis. The unfavourable outcome following the implantation of this stent is described.     

Targeting hepatitis B virus-infected cells with a T-cell receptor-like antibody

Virus-specific CD8 T cells are activated when their T-cell receptors (TCRs) recognize the specific viral peptide/major histocompatibility complex (MHC) class I (pMHC) complexes present on the surface of infected cells. Antibodies able to recognize the specific pMHC can mimic TCR specificity and both represent a valuable biological tool to visualize pMHC complexes on infected cells and serve as a delivery system for highly targeted therapies. To evaluate these possibilities, we created a monoclonal antibody able to specifically recognize a hepatitis B virus (HBV) envelope epitope (Env at positions 183 to 91 [Env183-91]) presented by the HLA-A201 molecule, and we tested its ability to recognize HBV-infected hepatocytes and to deliver a cargo to a specific target. We demonstrate that this antibody detects and visualizes the processed product of HBV proteins produced in naturally HBV-infected cells, is not inhibited by soluble HBV proteins present in patient sera, and mediates the intracellular delivery of a fluorescent molecule to target cells. Additionally, compared to CD8 T cells specific for the same HBV epitope, the TCR-like antibody has both a superior sensitivity and a specificity focused on distinct amino acids within the epitope. These data demonstrate that a T-cell receptor-like antibody can be used to determine the quantitative relationship between HBV replication and specific antigen presentation to CD8 T cells and serves as a novel therapeutic delivery platform for personalized health care for HBV-infected patients.     

Biosynthesis of chlorophyll P-680 of photosystem II in greening leaves of plants adapted to heat shock

In etiolated pea and maize leaves illuminated after incubation at 38 degreesC, a new dark reaction was shown manifested in the bathochromic shift of spectral bands and accompanied by esterification of the product of protochlorophyllide photochemical reduction--Chld 684/676: Chld 684/676 --> Chl 688/680. After completion of the reaction a rapid (20-30 sec) quenching of the fluorescence of the reaction product (Chl 688/680) was observed. The reaction Chld 684/676 --> Chl 688/680 is inhibited under anaerobic conditions and in the presence of cyanide; the reaction accompanied by Chl 688/680 fluorescence quenching is not observed in pea mutants with impaired function of photosystem II reaction centers. The spectral properties of the formed Chl form with the absorption maximum at 680 nm, fluorescence quenching, and simultaneous synthesis of pheophytin suggest that the reaction is connected with the chlorophyll of photosystem II reaction center--P-680.     

Late thrombotic occlusion of a malapposed stent 10 months after intracoronary brachytherapy

We report a patient who received a stent following intracoronary 3-irradiation. Despite a good initial angiographic result, the stent appeared to be not fully expanded on intravascular ultrasound imaging at 6-month follow-up. Four months later, sudden thrombotic occlusion occurred shortly after aspirin cessation.     

Lectin histochemistry for detecting cadmium-induced changes in the glycosylation pattern of rat placenta

Cadmium (Cd) is an industrial and environmental pollutant that produces toxic effects on gametogenesis, pre- and post-implantation embryos, and the placenta. Because the effects of acute Cd intoxication on the placenta are not well understood, we investigated changes in its glycosylated components in Cd treated dams at days 4, 7, 10 and 15 of gestation using lectin histochemistry. CdCl₂ was administered to pregnant rats; control animals received sterile normal saline. Placentas were processed for DBA, Con A, SBA, PNA, UEA-I, RCA-I and WGA lectin histochemistry to evaluate changes in the carbohydrate pattern of the placenta that might modify cell interactions and contribute to embryonic alterations. Lectin binding was analyzed in the yolk sac; trophoblast giant cells; trophoblast I, II and III; spongiotrophoblast cells and endovascular trophoblast cells in the chorioallantoic placenta. Our lectin binding patterns showed that Cd caused alteration of SBA and DBA labeling of trophoblast-derived cells, which suggested increased expressions of α and β GalNAc. Cd also caused decreased UEA-1 binding affinity, which indicated fewer α-L-Fuc residues in placentas of Cd treated dams. The nonreactivity in trophoblast I of the control placentas incubated with Con-A contrasted with the labeling in placentas of experimental dams, which indicated increased expression of terminal α-D-Man, and α-D-Glc residues. We found that Cd altered the reactivity of placenta to several lectins, which indicated modification of the glycotype presented by the fetal component of the placenta. We report that Cd exerts a deleterious effect on the glycosylation pattern of the placenta.