Cognitive behaviour therapy for adolescents with chronic fatigue syndrome: randomised controlled trial

Objective To evaluate the efficacy of cognitive behaviour therapy for adolescents aged 10-17 years with chronic fatigue syndrome.Design Randomised controlled trial.Setting Department of child psychology.Participants 71 consecutively referred patients with chronic fatigue syndrome; 36 were randomly assigned to immediate cognitive behaviour therapy and 35 to the waiting list for therapy.Intervention 10 sessions of therapy over five months. Treatment protocols depended on the type of activity pattern (relatively active or passive). All participants were assessed again after five months.Main outcome measures Fatigue severity (checklist individual strength), functional impairment (SF-36 physical functioning), and school attendance.Results 62 patients had complete data at five months (29 in the immediate therapy group and 33 on the waiting list). Patients in the therapy group reported significantly greater decrease in fatigue severity (difference in decrease on checklist individual strength was 14.5, 95% confidence interval 7.4 to 21.6) and functional impairment (difference in increase on SF-36 physical functioning was 17.3, 6.2 to 28.4) and their attendance at school increased significantly (difference in increase in percentage school attendance was 18.2, 0.8 to 35.5). They also reported a significant reduction in several accompanying symptoms. Self reported improvement was largest in the therapy group.Conclusion Cognitive behaviour therapy is an effective treatment for chronic fatigue syndrome in adolescents.     

Mutational and computational analysis of the role of conserved residues in the active site of a family 18 chitinase.

Glycoside hydrolysis by retaining family 18 chitinases involves a catalytic acid (Glu) which is part of a conserved DXDXE sequence motif that spans strand four of a (betaalpha)8 barrel (TIM barrel) structure. These glycoside hydrolases are unusual in that the positive charge emerging on the anomeric carbon after departure of the leaving group is stabilized by the substrate itself (the N-acetyl group of the distorted -1 sugar), rather than by a carboxylate group on the enzyme. We have studied seven conserved residues in the catalytic center of chitinase B from Serratia marcescens. Putative roles for these residues are proposed on the basis of the observed mutational effects, the pH-dependency of these effects, pKa calculations and available structural information. The results indicate that the pKa of the catalytic acid (Glu144) is 'cycled' during catalysis as a consequence of substrate-binding and release and, possibly, by a back and forth movement of Asp142 between Asp140 and Glu144. Rotation of Asp142 towards Glu144 also contributes to an essential distortion of the N-acetyl group of the -1 sugar. Two other conserved residues (Tyr10 and Ser93) are important because they stabilize the charge on Asp140 while Asp142 points towards Glu144. Asp215, lying opposite Glu144 on the other side of the scissile glycosidic bond, contributes to catalysis by promoting distortion of the -1 sugar and by increasing the pKa of the catalytic acid. The hydroxyl group of Tyr214 makes a major contribution to the positioning of the N-acetyl group of the -1 sugar. Taken together, the results show that catalysis in family 18 chitinases depends on a relatively large number of (partly mobile) residues that interact with each other and the substrate.     

Progressive formation of DNA lesions during treatment with anti-metabolites without incorporation of the drugs into DNA

Anti-metabolites, such as methotrexate, 5-fluoropyrimidines or hydroxyurea, induced progressive formation of DNA lesions. 5-Fluoropyrimidines induce DNA lesions either by incorporation of the drug into DNA or by a mechanism not involving incorporation. The second mechanism, not involving incorporation, is also seen with methotrexate and hydroxyurea. The three anti-metabolites have in common their ability to reduce intracellular levels of nucleotides, resulting in reduced efficiency of repair of DNA lesions. The lesions probably appear spontaneously, independently of the drug treatment.     

S-adenosylmethionine decarboxylase from Leishmania donovani. Molecular, genetic, and biochemical characterization of null mutants and overproducers.

The polyamine biosynthetic enzyme, S-adenosylmethionine decarboxylase (ADOMETDC) has been advanced as a potential target for antiparasitic chemotherapy. To investigate the importance of this protein in a model parasite, the gene encoding ADOMETDC has been cloned and sequenced from Leishmania donovani. The Delta adometdc null mutants were created in the insect vector form of the parasite by double targeted gene replacement. The Delta adometdc strains were incapable of growth in medium without polyamines; however, auxotrophy could be rescued by spermidine but not by putrescine, spermine, or methylthioadenosine. Incubation of Delta adometdc parasites in medium lacking polyamines resulted in a drastic increase of putrescine and glutathione levels with a concomitant decrease in the amounts of spermidine and the spermidine-containing thiol trypanothione. Parasites transfected with an episomal ADOMETDC construct were created in both wild type and Delta adometdc parasites. ADOMETDC overexpression abrogated polyamine auxotrophy in the Delta adometdc L. donovani. In addition, ADOMETDC overproduction in wild type parasites alleviated the toxic effects of 5'-(((Z)-4-amino-2-butenyl)methylamino)-5'-deoxyadenosine (MDL 73811), but not pentamidine, berenil, or methylglyoxyl bis(guanylhydrazone), all inhibitors of ADOMETDC activities in vitro. The molecular, biochemical, and genetic characterization of ADOMETDC establishes that it is essential in L. donovani promastigotes and a potential target for therapeutic validation.     

Aspects of floral structure and phenology in the genusConophytum (Mesembryanthemaceae)

The complex floral structure in the southern African genusConophytum (Mesembryanthemaceae; 77 spp.) is described in detail and assigned to three basic floral types, two of which can be divided into two subtypes. Correlations between structural features and phenological patterns are demonstrated and discussed in the family context as well as in relation to the systematic subdivision of the genus.     

Microtubule formation on the nuclear surface during meiosis inAcetabularia acetabulum

Summary Microtubules (MT) are a feature of all eukaryotic cells. However, they have not been observed in the cytoplasm of the vegetative phase ofAcetabularia acetabulum. Previous investigators have reported that, in the propagative phase, MTs function as anchors in the transport of secondary nuclei to the cap. They also form elaborate arrays around nuclei during cyst formation. The life history ofA. acetabulum is marked by changes in chromatin, the nucleolus, and the perinuclear cytoplasm. In this study light microscopical features of the nucleolus and changes in chromatin, labelled with anti-histon antibodies, were used to define the developmental stages. Anti-tubulin antibodies have been used to trace the origin and development of MTs, MTs are formed on the surface of the primary nucleus. They are organized first into short thick sticks and then later elongate into thinner strands which enclose the nucleus in a dense network. Following these events on the surface of the nucleus, the spindle develops inside the nuclear membrane which remains intact throughout the mitotic division.