Structural similarity of DNA-binding domains of bacteriophage repressors and the globin core

BACKGROUND: In recent years, the determination of large numbers of protein structures has created a need for automatic and objective methods for the comparison of structures or conformations. Many protein structures show similarities of conformation that are undetectable by comparing their sequences. Comparison of structures can reveal similarities between proteins thought to be unrelated, providing new insight into the interrelationships of sequence, structure and function. RESULTS: Using a new tool that we have developed to perform rapid structural alignment, we present the highlights of an exhaustive comparison of all pairs of protein structures in the Brookhaven protein database. Notably, we find that the DNA-binding domain of the bacteriophage repressor family is almost completely embedded in the larger eight-helix fold of the globin family of proteins. The significant match of specific residues is correlated with functional, structural and evolutionary information. CONCLUSION: Our method can help to identify structurally similar folds rapidly and with high-sensitivity, providing a powerful tool for analyzing the ever-increasing number of protein structures being elucidated.     

Presence of cholesterol ester synthetase activity in guinea pig gallbladder epithelium.

This study is the first to demonstrate the presence of cholesteryl ester synthetase activity in the gallbladder epithelium. Using epithelium of the guinea pig gallbladder, the study demonstrated that the enzyme was localized mainly in the particulate fraction. The enzyme required CoA and ATP for activity and displayed a pH optimum of 7.0. The uptake of biliary cholesterol by gallbladder (shown by other investigators) and the presence of cholesteryl ester synthetase activity (demonstrated in this study) suggest that the gallbladder epithelium has an active role which might be important in conditions of cholesterol supersaturation in bile.     

9-beta-D-Arabinofuranosyl-8-n-butylaminoadenine, a C-8 substituted nucleoside in the anti conformation. Crystallographic and NMR studies

The protein NMR spectrum of 9-beta-D-arabinofuranosyl-8-n-butylaminoadenine shows an unusually low-field 5'-hydroxyl proton resonance, which has been interpreted in terms of an anti glycosidic conformation together with an 05' ... N8 intramolecular hydrogen bond. Confirmatory evidence for this was obtained by an X-ray crystallographic study; in the crystal, the glycosidic angle chi is 52.7 degrees and the sugar pucker is C3' endo-C4' exo.     

Loss Mechanisms in Thick‐Film Low‐Bandgap Polymer Solar Cells

Polymer bulk heterojunction solar cells based on low bandgap polymer:fullerene blends are promising for next generation low‐cost photovoltaics. While these solution‐processed solar cells are compatible with large‐scale roll‐to‐roll processing, active layers used for typical laboratory‐scale devices are too thin to ensure high manufacturing yields. Furthermore, due to the limited light absorption and optical interference within the thin active layer, the external quantum efficiencies (EQEs) of bulk heterojunction polymer solar cells are severely limited. In order to produce polymer solar cells with high yields, efficient solar cells with a thick active layer must be demonstrated. In this work, the performance of thick‐film solar cells employing the low‐bandgap polymer poly(dithienogermole‐thienopyrrolodione) (PDTG‐TPD) was demonstrated. Power conversion efficiencies over 8.0% were obtained for devices with an active layer thickness of 200 nm, illustrating the potential of this polymer for large‐scale manufacturing. Although an average EQE > 65% was obtained for devices with active layer thicknesses > 200 nm, the cell performance could not be maintained due to a reduction in fill factor. By comparing our results for PDTG‐TPD solar cells with similar P3HT‐based devices, we investigated the loss mechanisms associated with the limited device performance observed for thick‐film low‐bandgap polymer solar cells.     

Targetted localisation and imaging of a murine lymphoma using 131I-labelled monoclonal antibody

In vivo tumor targetting with radiolabelled monoclonal antibodies is a promising approach for the diagnosis and therapy of tumors. A specific monoclonal antibody (mAb), DLAB was generated to the Dalton's lymphoma associated antigen (DLAA) from Haemophilus paragallinarum-induced spontaneous fusion. In order to study the tumor localisation and biodistribution properties of the monoclonal antibody, scintigraphic studies were performed using the radiolabelled DLAB. 131-labelled DLAB was administered intravenously into Swiss mice bearing Dalton's lymphoma and external scintiscanning was performed at different time intervals. Clear tumor images were obtained which revealed selective and specific uptake of radiolabel and the results were compared with biodistribution data. The radioiodinated monoclonal antibody showed fast tumor uptake which increased significantly to 14.6% injected dose (ID)/g at 12 hr post-injection. Enhanced blood clearance of radioactivity resulted in higher tumor/blood ratio of 5.96 at 48 hr. 131I-labelled DLAB resulted in selective and enhanced uptake of the radioactivity by the tumor compared to the non-specific antibody and the results suggest the potential use of spontaneous fusion for producing specific monoclonal antibodies for tumor detection and therapy.     

The hemagglutinin-neuraminidase protein of Newcastle disease virus determines tropism and virulence

The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) plays a crucial role in the process of infection. However, the exact contribution of the HN gene to NDV pathogenesis is not known. In this study, the role of the HN gene in NDV virulence was examined. By use of reverse genetics procedures, the HN genes of a virulent recombinant NDV strain, rBeaudette C (rBC), and an avirulent recombinant NDV strain, rLaSota, were exchanged. The hemadsorption and neuraminidase activities of the chimeric viruses showed significant differences from those of their parental strains, but heterotypic F and HN pairs were equally effective in fusion promotion. The tissue tropism of the viruses was shown to be dependent on the origin of the HN protein. The chimeric virus with the HN protein derived from the virulent virus exhibited a tissue predilection similar to that of the virulent virus, and vice versa. The chimeric viruses with reciprocal HN proteins either gained or lost virulence, as determined by a standard intracerebral pathogenicity index test of chickens and by the mean death time in chicken embryos (a measure devised to classify these viruses), indicating that virulence is a function of the amino acid differences in the HN protein. These results are consistent with the hypothesis that the virulence of NDV is multigenic and that the cleavability of F protein alone does not determine the virulence of a strain.     

Time course studies on the functional evaluation of experimental chronic myocardial infarction in rats

In vivo models of myocardial infarction induced by coronary artery ligation (CAL) in rats usually suffer from high early mortality and a low rate of induction. This study investigated the time course initiation of chronic myocardial infarction (CMI) in albino rats and the possibility of reducing early mortality rate due to myocardial infarction by modification of the surgical technique. CAL was carried out by passing the suture through the epicardial layer around the midway of the left anterior descending coronary artery including a small area of the myocardium to avoid mechanical damage to the heart geometry. In addition, the role of endothelin-1 (ET-1) in rat heart with congestive heart failure was critically assessed. Time course initiation experiments were designed by sacrificing the animals at different time intervals and by carrying out physiological, biochemical, histopathological, electron microscopical and immunohistochemical studies. Specific markers of myocardial injury, viz. cardiac troponin-T (cTnT), high sensitivity C-reactive protein, lactate dehydrogenase and fibrinogen were measured at different time points. Serum marker enzymes and activities of lysosomal hydrolases were found to be elevated on the eighth day post-ligation. Histopathological studies demonstrated focal areas showing fibrovascular tissue containing fibroblasts, collagenous ground substance and numerous small capillaries replacing cardiac muscle fibers. Transmission electron micrographs exhibited mitochondrial changes of well-developed irreversible cardiac injury, viz. swelling, disorganization of cristae, appearance of mitochondrial amorphous matrix densities, significant distortion of muscle fibers and distinct disruption of the intercalated discs. Immunoblotting studies confirmed the presence of alpha 2-macroglobulin which supported the inflammatory response. The severity of the CMI was inferred by the measurement of the level of ET-1 in plasma and left ventricle which was significantly higher in the CMI rats than in the sham-operated rats. Immunohistochemical studies at different time intervals showed that there was a significant immunoexpression of ET-1 on the eighth day post-ligation. This study conclusively showed that ligation of left anterior descending artery minimized mortality and ET-1 was expressed during CMI.     

SP600125, an inhibitor of c-jun N-terminal kinase,activates CREB by a p38 MAPK-mediated pathway

SP600125, an anthrapyrazolone inhibitor of c-jun N-terminal kinase (JNK), has been used to characterize the role of JNK in apoptotic pathways. In this study, we have demonstrated an additional novel anti-apoptotic action of this inhibitor in MIN6 cells, a mouse beta cell line. SP600125 induced CREB-dependent promoter activation by 2.8-fold at 20 microM, the concentration at which it inhibited c-jun-dependent promoter activation by 51%. There was a significant (P<0.01) increase in CREB phosphorylation (serine 133) at 5 min, which persisted for a period of 2h. Examination of signaling pathways upstream of CREB showed a 2.5-fold increase in the active phospho form of p38 MAPK. This finding was further confirmed by an in vitro kinase assay using ATF-2 as substrate. SB203580, an inhibitor of p38 MAPK, partially blocked SP600125-mediated activation of CREB. These observations suggest that SP600125 could be used as a small molecular weight activator of CREB.