Deletion ΔF508 and haplotype analysis of CFTR gene region in Slovak CF patients

Summary Analysis of a sample of 50 unrelated cystic fibrosis (CF) patients and 46 nuclear families from Slovakia (Czechoslovakia) by the polymerase chain reaction and Southern hybridization revealed that the proportion of the F508 mutation was 58% in this population, and that the frequency of the B (i.e., KM19/XV2c [1–2]) haplotype was increased in both F508 and nonF508 CF chromosomes (98% and 46%, respectively). These results support the view that the trans-European gradient of the F508 frequency is of a geographical rather than of an ethnic origin, and that in Slavonic populations, there exists an as yet unidentified but frequent CF mutation other than F508, associated with the B haplotype.     

HLA gene and haplotype frequencies in galicia (NW Spain)

The genetic structure of six populations of Iran (Turks, Kurds, Lurs, Zabolis, Baluchis and Zoroastrians) was examined using data on blood groups, serum proteins and cell enzymes. Our results show conclusively that there are genetic differences among the six populations and the analysis of superimposed R and S matrices defined by Harpending & Jenkins (1973) show that the dispersion of some of the alleles correspond to the dispersion of the populations. The F_ST estimates are not large enough to favour selection on any of the loci studied. The F_IT and F_IS estimates are positive and moderately high suggesting that the genetic differentiation to some extent is influenced by inbreeding.     

Effect of Zeitgeber Intensity Reduction on a Simulated Dual-Oscillator Human Circadian System: Classical and Dynamic Analysis

The two-oscillator model of human circadian rhythmicity was analyzed when a zeitgeber relative intensity of 1, 0.5, or 0.1 was introduced into the equations. Fourier analysis was compared with dynamic analysis such as attractor reconstruction or Liapunov exponent calculation. After a 50 or 90% reduction in zeitgeber intensity, the dynamics of the system became equivalent and differed significantly from those of a system with maximal zeitgeber intensity. When 10% aleatory noise was added to the data, the analysis was still applicable, and the results obtained were essentially the same as in the absence of noise. Dynamic analysis could thus provide a distinct classification for periodic data, based on the type of analysis.     

Influence of age and gamma irradiation on the proliferative activity in regenerating rat liver.

The effect of aging (2-14 months) and total body irradiation (5.7 Gy of gamma radiation) on liver regeneration was investigated in rats 30 h after partial hepatectomy. Exposure of rats to irradiation 30 min before partial hepatectomy caused latent injury in the remaining liver cells. During the course of liver regeneration this became manifested as a delay in increasing the nucleic acid concentration and content and liver weight and, furthermore, as inhibition of the increase in the mitotic index and cellularity and pronounced increase in the frequency of chromosome aberrations in the postmetaphase. The pattern of age-related changes during liver regeneration was the same as that after irradiation, so that the differences between irradiated and nonirradiated animals became smaller with age.     

Benzodiazepines in the brain

Great progress has been made in the last 5 yr in demonstrating the presence of benzodiazepines (BDZs) in mammalian tissues, in beginning studies on the origin of these natural compounds, and in elucidating their possible biological roles. Many unanswered questions remain regarding the sources and biosynthetic pathways responsible for the presence of BDZs in brain and their different physiological and/or biochemical actions. This essay will focus on recent findings supporting that: (1) BDZs are of natural origin; (2) mammalian brain contains BDZs in concentrations ranging between 5.10⁻¹⁰–10⁻⁸ M; (3) dietary source of BDZs might be a plausible explanation for their occurrence in animal tissues, including man; (4) the formation of BDZ-like molecules in brain is a possibility, experimentally supported; (5) BDZ-like molecules including diazepam andN-desmethyldiazepam are elevated in hepatic encephalopathy; and (6) natural BDZs in the brain are involved in the modulation of memory processes. Future studies using the full range of biochemical, physiological, behavioral, and molecular biological techniques available to the neuroscientist will hopefully continue to yield exciting and new information concerning the biological roles that BDZs might play in the normal and pathological functioning of the brain.     

Identification and characterization of sex-linked proteins of Schistosoma mansoni.

The proteins of adults worms (male and female) of two isolates (BH and RJ) of Schistosoma mansoni were extracted using Triton X-114 phase separation. The SDS-polyacrilamide gel electrophoresis profiles of the three phases (detergent, aqueous and insoluble proteins) obtained were compared after Coomassie blue and silver staining, surface radioiodination and Western blotting. No major differences were detected between the 2 isolates. Of the 25 or more proteins which partitioned into the detergent phase, only about 8 proteins could be surface radiodinated on live adult worms. A comparison was also made between the profiles of male and females worms, isolated from bisexually infected mice. Two major female-specific and one male-specific band were detected by silver and/or Coomassie staining. The female bands, 32 KDa and 18 KDa, partitioned into the detergent and aqueous phase, respectively. The male-specific band of 42 KDa remained in the insoluble phase. Antigenic differences between male and females proteins were detected by Western blotting using a sera from infected Nectomys squamipes.     

Structure of the HLA-A*0204 antigen,found in South American Indians. Spatial clustering of HLA-A2 subtype polymorphism

The primary structure of the HLA-A2 subtype A^*0204 (isoelectric focusing variant A2.A) has been determined. cDNA encoding this subtype was amplified by the polymerase chain reaction. Four independent full-lenght cDNA clones encoding A^*0204 were analyzed to obtain a consensus sequence for this subtype. A^*0204 differs from A^*0201 by a single nucleotide change of G to T through the coding regions, resulting in an Arg to Met change at position 97. This substitution accounts for the isoelectric focusing pattern of the subtype. The same change occurs in other HLA-A specificities in association with other changes in its vicinity. The absence of additional substitutions in A^*0204 suggests that it could have arisen from A^*0201 by point mutation, and that recurrent mutations may take place during HLA diversification. The spatial location of this change implies that A^*0204 must be a functional variant. Comparison of its sequence with other HLA-A2 subtypes reveals that much of the HLA-A2 subtype polymorphism is generated by variations in four neighboring positions, including position 97, which are located in two adjacent -strands on the floor of the peptide binding site of the molecule.The nucleotide sequence data reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession number X57954. Address correspondence and offprint requests to: J. A. López de Castro.     

Enzymatic hydrolysis of 2,2,2,-trifluoroethyl α-chloro-α-phenylacetate in organic media

Summary 2,2,2-Trifluoroethyl -chloro--phenylacetate is succesfully hydrolysed in organic solvent in the presence of aniline andCandida cylindracea orPseudomonas cepacia lipase as catalysts.     

A semiempirical study of the prototropic tautomerism of hypoxanthine

The total and relative energies, bond order matrices and localized MOs for the eight possible tautomers of hypoxanthine (HYP) have been calculated, with full geometry optimization, using both AM1 and MNDO methods. The AM1 relative energies show that HYP(9,1), HYP(7,1) and HYP (9,10) are the predominant species at room temperature, the two former being in larger concentration that the latter. The calculated IR spectra for these species agree well with the reported spectrum in an isolated matrix, which has been interpreted in terms of the presence of these three tautomeric forms. The MNDO method does not predict the right order, and the more stable tautomer would be HYP(9,10). The calculated structure for the HYP(9,1) species shows that the molecule is essentially planar. The bond distances compare well with those of hypoxanthine hydrochloride and guanine and also correlate well with the calculated bond orders. The proton affinities for the three more stable tautomers have also been calculated. For HYP(9,1) the prefered site of protonation is N7, whereas for HYP(7,1) the protonation occurs rather at N9. These results agree well with¹⁵N and¹³C NMR studies in DMSO.     

Nuclear location of phosphoglycerate mutase BB isozyme in rat tissues

Summary We have previously reported (Ureña et al. Eur. J. Cell Biol. 1990) that in skeletal muscle, type MM phosphoglycerate mutase isozyme is present in the nucleus as well as in the cytosol. To determine whether type BB phosphoglycerate mutase isozyme is also present in nucleus, the subcellular location of this isozyme was studied in different rat tissues by cell fractionation and immunogold techniques. With the aid of high affinity-purified anti-phosphoglycerate mutase BB isozyme antibodies, the isozyme was located in the nucleus of neuronal, astroglial and liver cells but not in the nucleus of oligodendroglial and endothelial cells. Biochemical studies on purified nuclear fractions also demonstrated the presence of phosphoglycerate mutase activity in the nucleus. Both immunocytochemical and biochemical techniques showed that nuclear phosphoglycerate mutase-specific activity depended on the type of cell.Abbreviations PGAM phosphoglycerate mutase - PGAM-M(M) muscle specific subunit (isozyme) of PGAM - PGAM-B(B) brain type subunit (isozyme) of PGAM - ssDNA single stranded DNA - PBS 0.001 M phosphate buffer, pH 7.4, containing 0.15 M NaCl - kDa kilodalton