Acute nonspecific carditis in adolescents presenting with Stokes-Adams attacks.

Three patients, aged between 12 and 17 years presented with Stokes-Adams attacks as a result of atrioventricular block, atrioventricular silence and ventricular arrhythmias, complicating acute myocarditis. All the patients required temporary pacing for a few days. One patient required hemodialysis for anuria. All the patients made complete recovery.

Molecular analysis of the promoter region of the gene encoding the beta-amyloid precursor protein.

The amyloid beta-peptide (approximately 4 kDa-M(r)) is generated by the proteolytic cleavage of a larger beta-amyloid precursor protein (beta APP) encoded by a gene on chromosome 21. The abnormality in gene regulation of beta APP may be an important factor in the neuropathology of Alzheimer's disease. The control of transcription is mediated by different DNA regulatory elements (cis-acting) present in the promoter of the gene. There are about 26 DNA motifs, present in the immediate 5'-flanking region of the beta APP gene, through which various cell/tissue-specific factors (trans-acting) can exert their influence on transcription. Here, the effects of nerve growth factor (NGF), basic fibroblast growth factor (bFGF), phorbol 12-myristate 13-acetate (PMA), interleukin-1 (IL-1) and retinoic acid (RA) on promoter activity of the beta APP gene were analyzed. To investigate the effect of these factors on promoter activity, a recombinant plasmid which contained sequences of -489 base pairs (bp) from the 5'-flanking region of the beta APP gene was used. The truncated region of the promoter was linked upstream to a reporter gene, chloramphenicol acetyl transferase (CAT). Promoter activity was tested by transient transfection of the fusion plasmid in PC12 cells using the electroporation method (960 microF at 350 V). The treatment of PC12 cells with either NGF, bFGF, PMA, IL-1 or RA stimulated the activity of the beta APP promoter. Treatment of cells with either NGF or bFGF resulted in a higher level of stimulation in the basal level of promoter activity than when cells were treated with either PMA, IL-1 or RA. The pre-treatment of cells with these factors for a duration of 4 days prior to transfection with the promoter plasmid was necessary for the stimulatory effect. The cells that were treated with either of these factors after transfection showed no significant change in the basal level of promoter activity. Thus, certain growth factors and a cytokine could enhance the basal level of promoter activity of the beta APP gene, suggesting a possible participation of a growth-factor (s)-mediated transcriptional element in the control of gene expression of beta APP.

Presence of precursor ribosome in the ribosomal preparation from chloramphenicol-treated Escherichia coli ΑΒ301/Ι05 (RNase III – ).

On sucrose gradient centrifugation, the ribosomal preparation from chloramphenicoltreated 32P labelled Escherichia coli AB301/105 (RNase III¯ ) showed the presence of a radioactive peak moving slower than the 70S ribosome; this peak disappeared on treatment with RNase III. The presence of precursor 30S RNA was shown in such preparations by affinity chromatography on a lysine-sepharose 4B column as well as polyacrylamide gel electrophoresis. Dialysis against low Mg2± concentration followed by sucrose density gradient electrophoresis. Dialysis against dissociation of 70S ribosome into its subunits, did not lead to the dissociation of the precursor ribosome. However, the dissociation took place upon treatment with RNase III. A tentative model of coupled rRNA transcription and ribosome assembly has been presented.

Immunoprecipitation of 70S, 50S and 30S ribosomes of Escherichia coli.

Antibodies were raised in rabbits against 70S ribosomes, 50S and 30S ribosomal subunits individually. Purified immunoglobulins from the antiserum against each of the above ribosomal entities were tested for their capabilities of precipitating 70S, 50S and 30S ribosomes. The observations revealed the following: (i) The antiserum (IgG) raised against 70S ribosomes precipitates 70S ribosomes completely, while partial precipitation is seen with the subunits, the extent of precipitation being more with the 50S subunits than with 30S subunits; addition of 50S subunits to the 30S subunits facilitates the precipitation of 30S subunits by the antibody against 70S ribosomes. (ii) Antiserum against 50S subunits has the ability to immunoprecipitate both 50S and 70S ribosomes to an equal extent. (iii) Antiserum against 30S subunits also has the property of precipitating both 30S and 70S ribosomes. The differences in the structural organisation of the two subunits may account for the differences in their immunoprecipitability.