Analysis of the binding of p-chlorophenyl-methoxybenzyl-ketoxime (CPMB-oxime) to mitochondrial cytochrome c reductase.

Cytochrome c reductase is inhibited by p-chlorophenyl-methoxybenzyl-ketoxime (CPMB-oxime). CPMB-oxime induces a red-shift of the reduced spectrum of cytochrome b. The inhibitor blocks the oxidation of ubihydroquinone at the QP center of this enzyme in a non-competitive way. The binding stoichiometry equals one inhibitor molecule per Qp center. The apparent Kd in a red-shift assay was 6.9 +/- 0.6 microM. All binding characteristics analysed in this study were very similar to those of the E-beta-methoxyacrylate inhibitors, although the chemical structure is different from these inhibitors. This result is interpreted as a support for the inhibitory mechanism based on the model of a 'catalytic switch' proposed recently for the E-beta-methoxyacrylate inhibitors (MOA-inhibitors (Brandt and von Jagow, Eur. J. Biochem.     

Phospholipase A2 activity in human platelets. Isolation and purification of the enzyme

The activity of phospholipase A2 in blood platelets of healthy donors and IHD patients was examined. The enzyme activity was found to be increased 3-fold in platelets possessing a high level of functional activity (IHD) and by one order of magnitude in patients with myocardial infarction as compared with healthy donors. An enzyme preparation possessing a phospholipase activity was isolated from platelets by using salt extraction (KCl) and sonication. Purification of the enzyme by affinity chromatography resulted in two protein peaks both having a phospholipase A2 activity, the purification and molecular masses of these fractions being 768- and 2200-fold, and 13.5 and 15 kDa, respectively. It was supposed that these proteins are substrate-specific forms of phospholipase A2.     

Detection and characterization of mitochondrial DNA rearrangements in Pearson and Kearns-Sayre syndromes by long PCR

We used a strategy based on long PCR (polymerase chain reaction) for detection and characterization of mitochondrial DNA (mtDNA) rearrangements in two patients with clinical signs suggesting Pearson syndrome and Kearns-Sayre syndrome (KSS), respectively, and one patient with myopathic symptoms of unidentified origin. Mitochondrial DNA rearrangements were detected by amplification of the complete mitochondrial genome (16.6 kb) using long PCR with primers located in essential regions of the mitochondrial genome and quantified by three-primer PCR. Long PCR with deletion-specific primers was used for identification and quantitative estimation of the different forms of rearranged molecules, such as deletions and duplications. We detected significant amounts of a common 7.4-kb deletion flanked by a 12-bp direct repeat in all tissues tested from the patient with Pearson syndrome. In skeletal muscle from the patient with clinical signs of KSS we found significant amounts of a novel 3.7-kb rearrangement flanked by a 4-bp inverted repeat that was present in the form of deletions as well as duplications. In the patient suffering from myopathic symptoms of unidentified origin we did not detect rearranged mtDNA in blood but found low levels of two rearranged mtDNA populations in skeletal muscle, a previously described 7-kb deletion flanked by a 7-bp direct repeat and a novel 6.6-kb deletion with no repeat. These two populations, however, were unlikely to be the cause of the myopathic symptoms as they were present at low levels (10–40 ppm). Using a strategy based on screening with long PCR we were able to detect and characterize high as well as low levels of mtDNA rearrangements in three patients. Received: 10 March 1997 / Accepted: 20 May 1997     

A rRNA-mRNA base pairing model for UGA-dependent termination.

A series of site-directed mutations has been constructed in E coli 16S rRNA and shown to suppress UGA-dependent translational termination. With the exception of the C726 to G base change, all were constructed in helix 34. Characterization of these mutations is reviewed here and from these data and mRNA-rRNA base pairing model for the termination event is presented. The interaction functions via antiparallel base pairing between either 1 of the 2 UCA motifs in helix 34 and the complementary UGA stop codon on the message, thus forming a quasicontinuous A-type helical structure that is further stabilized by stacking enthalpy. Finally, rRNA motifs potentially required for UAA and UAG-dependent translational termination are discussed.     

Randomised,double blind,placebo controlled trial of penicillin V and amoxycillin in treatment of acute sinus infections in adults.

OBJECTIVES--To compare the effectiveness of penicillin V and amoxycillin with placebo in treatment of adult patients with acute sinusitis. DESIGN--Randomised, double blind, placebo controlled trial. SETTING--Norwegian general practice. SUBJECTS--130 adult patients with a clinical diagnosis of acute sinusitis confirmed by computed tomography. MAIN OUTCOME MEASURES--Subjective status after three and 10 days of treatment, difference in clinical severity score between day 0 and day 10 as evaluated by the general practitioner, difference in score from computed tomography on day 0 and day 10, and duration of sinusitis. RESULTS--Amoxycillin and penicillin V led to significantly faster and better recovery than placebo. By day 10, 71 patients receiving antibiotic treatment- (86%) considered themselves to be recovered or much better compared with 25 (57%) receiving placebo. The mean (95% confidence interval) reductions in clinical severity scores by day 10 were 5.4 (5.0 to 5.8) for penicillin V, 5.5 (4.9 to 6.0 for amoxycillin, and 3.4 (2.8 to 4.0) for placebo. For the antibiotic groups combined the number of patients with the greatest degree of improvement on computed tomography (scale 0-16)-that is, score 5-16 on day 10-was 31/83 (37%) compared with 10/44 (23%) receiving placebo. The median duration of the sinusitis was nine days in the amoxycillin group, 11 days in the penicillin V group, and 17 days in the placebo group. CONCLUSION--Penicillin V and amoxycillin are significantly more effective than placebo in the treatment of acute sinusitis.