Continuous non-invasive blood pressure monitoring in patients with sleep disorders.

Sleep related breathing disorders are of high prevalence and are often associated with essential hypertension. It is therefore necessary to study blood pressure continuously in all patients with sleep related breathing disorders and arterial hypertension as well as in all patients with essential hypertension and suspected sleep apnoea. To investigate the usefulness of a non-invasive continuous volume-clamp method during sleep we used this technique in parallel with 130 sleep recordings and performed a validation study of the Finapres instrument on a subgroup where continuous invasive blood pressure recordings were available. Absolute pressure values of Finapres are valid when the position and the movement of the sensor were carefully observed and only appropriate segments of the recordings were taken for further evaluation. The high beat to beat resolution of the systolic and diastolic pressure is the main advantage of this non-invasive technique because it reflects rapid blood pressure variations as they occur in sleep related breathing disorders. This could be investigated only invasively until now.     

Isolation and expression of linked zinc finger gene clusters on human chromosome 11q

Proteins that share conserved "zinc finger" motifs represent a class of DNA-binding proteins that have been shown to play a fundamental role in regulating gene expression and to be involved in a number of human hereditary and malignant disease states. We have isolated, characterized, and mapped zinc finger-encoding genes specific to human chromosome 11q to investigate their possible association in the molecular pathogenesis of several disease loci mapped to this chromosome. An arrayed chromosome 11q cosmid library was screened using a degenerate oligonucleotide corresponding to the H/C link consensus sequence of the Drosophila Kruppel zinc finger gene, resulting in the isolation of six putative zinc finger genes. Three of the genes (ZNF123, ZNF125, and ZNF126) were analyzed and shown to contain tandemly repeated zinc finger motifs of the C2-H2 class. All three novel genes were found to be expressed in normal adult human tissues, although the tissue-specific pattern of expression differs markedly. Isolated zinc finger genes were regionally mapped on chromosome 11 using fluorescence in situ suppression hybridization and demonstrated clustering of the genes at 11q13.3-11q13.4 and 11q23.1-11q23.2. Analysis of in situ hybridization to interphase nuclei demonstrated a maximum distance of 1 Mb separating distinct finger genes. This analysis defines two linked multigene families of zinc finger genes to chromosome bands associated with a high frequency of specific translocations associated with malignancies.     

The problem of natural antibodies, 1894–1905

As we have seen, natural antibodies first emerged as an experimental phenomenon without a plausible theoretical explanation. They were originally denied the status of antibody; then, adjustments to the side-chain theory transformed them from a curiosity into a foundation of the theory. However, in accommodating natural antibodies, Ehrlich had opened several holes in his mechanism of antibody formation.Thus, by 1905, natural antibodies were clearly established as problematic. From the practical standpoint, it seemed unwise to maintain an identity between normal and immune antibodies, given the therapeutic differences in their avidity. With the decline of Ehrlich's theory of antibody formation and the spread of Landsteiner's hapten technique for the production of antibodies against artificial antigens after World War I, the theoretical possibility of their existence as other than anomaly seemed more remote than ever. However, outside the theory and despite clinical considerations, natural antibodies remained a perplexing experimental phenomenon.⁴⁹     

Calcium-dependent protease of the cyanobacterium Anabaena: molecular cloning and expression of the gene in Escherichia coli, sequencing and site-directed mutagenesis

Summary It has been suggested that a calcium-dependent intracellular protease of the cyanobacterium, Anabaena sp., participates in the differentiation of heterocysts, cells that are specialized for fixation of N₂. Clones of the structural gene (designated prcA) for this protease from Anabaena variabilis strain ATCC 29413 and Anabaena sp. strain PCC 7120 were identified via their expression in Escherichia coli. The prcA gene from A. variabilis was sequenced. The genes of both strains, mutated by insertion of a drug resistance cassette, were returned to these same strains of Anabaena on suicide plasmids. The method of sacB-mediated positive selection for double recombinants was used to achieve replacement of the wild-type prcA genes by the mutated forms. The resulting mutants, which lacked Ca²⁺-dependent protease activity, were not impaired in heterocyst formation and grew on N₂ as sole nitrogen source.     

Proton and sucrose transport in isolated tonoplast vesicles from sugarcane stalk tissue

Tonoplast vesicles prepared from immature sugarcane ( Saccharum spp., hybrid cv. H65–7052) tissue and purified on a discontinuous dextran gradient take up sucrose. Uptake was stimulated by MgATP. Evidence that the mechanism is linked to proton transport is derived from "pH jump'data and from inhibition of ATP-stimulated sucrose transport by the protonophore carbonyl cyanide m -chlorophenylhydrazone (CCCP) and by the proton-channel blocker of proton-linked ATPases. N. N '-dicyclo-hexylcarbodiimide (DCCD). A saturable phase of sucrose uptake was found at low substrate concentrations, and a linear phase characterized uptake at higher concentrations. Uptake was specific for sucrose, as demonstrated by competition experiments with various sugars. Sucrose uptake by the vesicle fraction was inhibited by KNO₃, protonophores and protein modifying reagents, whereas sodium orthovanadate had no effect. Overall, the evidence suggests an ATP-hydrolysis-dependent tonoplasl antiport for sucrose transport, although a more direct influence of ATP on conformational changes in relevant tonoplast proteins cannot be ruled out.