Cytoskeletal interactions determine the electrophysiological properties of human EAG potassium channels

The electrophysiological properties of ether a go-go (EAG) potassium channels are modified during the cell cycle when they are expressed in heterologous systems. In Chinese hamster ovary (CHO) mammalian somatic cells we found that the cell-cycle-dependent modulation of human EAG (hEAG) channels occurs during the M phase. This modulation has three components: reduction in current density, increased sensitivity to block by intracellular sodium, and increased selectivity for potassium ions. In this work, these three properties have been used to define the mitotic phenotype of EAG currents. The signaling pathway leading to such changes of channel properties is unknown. We tested the hypothesis that cytoskeletal interactions might affect the electrophysiological changes observed during the cell cycle. The disruption of actin filaments induces a significant increase in current density, without inducing the cell-cycle-related phenotype. In contrast, disturbance of the microtubules, achieved by pharmacological means or by mechanical excision of the membrane patch, does induce the cell-cycle-related phenotype. Our results demonstrate that hEAG channels establish complex interactions with cytoskeletal elements, and that these interactions strongly influence the properties of the channels. We also conclude that the electrophysiological changes observed during the cell cycle are most likely due to reorganization of the cytoskeleton during the G2/M transition.

2-Hydroxyphenyl 2-methylpyrazolo[1,5-a]pyrimidin-6-yl ketone

The molecules of the title compound, C(14)H(11)N(3)O(2), form a three-dimensional soft hydrogen-bonded network involving C-H...N hydrogen bonds.

[Neuropsychology of temporal partial epilepsy: a comparison of drug resistant and pharmacologically controlled patients]

INTRODUCTION

Various factors may contribute to cognitive deterioration in temporal lobe epilepsy, and there is controversy as to which has the greatest effect.

PATIENTS AND METHODS

In this study, we establish a comparison between patients with temporal lobe epilepsy controlled by drugs and drug-resistant patients, with the object of discovering the effect of different factors in causing cognitive damage.

RESULTS

The persons whose disorder was controlled by pharmacological means had better results in memory and intelligence tests than those with drug-resistance. The latter had alterations of declarative memory for verbal material (left) and for visio-spatial material (right) in delayed free recall tests. Also, the greater proportion of symptomatic epilepsies in the drug-resistant group affected their greater cognitive deterioration.

CONCLUSIONS

Our results show that having long-standing epilepsy with great frequency of seizures and symptomatic epilepsy is correlated with cognitive alterations in memory function in temporal lobe epilepsy. Most deterioration is seen in patients with long-standing drug resistant symptomatic left mesial temporal epilepsy.

[Atrioventricular discordance. Clinico-surgical experience 1990-2000]

OBJECTIVE

To know the incidence of ventriculoarterial connections combined with atrioventricular discordance, associated lesions and surgical results, including the first case with anatomical correction.

METHOD

All patients with atrioventricular discordance by echocardiography from 1990 to March 2000 were analyzed.

RESULTS

Thirty six patients with atrioventricular discordance were found. Ages ranged from 0.1 to 46 years, with a mean 9.2 years (SD 5.9 years). Atrial chambers were situs solitus in 88.9%, inversus in 11.2%. The ventriculoarterial connections were discordant in 28 (77.7%), double outlet right ventricle in 4 (11.1%) (one of them was a "criss cross" heart), single outlet (pulmonary atresia) in 4 (11.1%), and double outlet left ventricle in 1 (2.7%). Associated lesions: Ventricular septal defect with pulmonary stenosis or atresia was present in 21 (58%), ventricular septal defect with no pulmonary obstruction was observed in 10 (28%). Five had tricuspid regurgitation with right ventricular disfunction, (two adults). Surgical results: 22 (61%) required 28 surgical procedures: 8 (36%) were palliative and 19 (86%) were corrective, one of them was our first anatomical correction. Operative mortality in all was 40.1%, postoperative atrioventricular block was observed in 9 (40.1%).

CONCLUSION

Right ventricular dysfunction is not uncommon. Surgical results revealed high mortality and high pacemaker requirement for atrioventricular block.

Simultaneous supercritical fluid derivatization and extraction of formaldehyde by the Hantzsch reaction

A study where the Hantzsch reaction is used to produce the chemical derivatization of formaldehyde in a supercritical medium is presented in this paper. Pressure, temperature and other parameters such as static and dynamic extraction time must be optimized to increase the yield of this kinetically controlled reaction. A 2(5-1) (resolution V) factorial design was used to study the significant parameters affecting the supercritical process in terms of resolution and sensitivity. A subsequent central composite design was employed to find the conditions of maximum response. Ultraviolet-visible spectrophotometry was used as the detection technique. The optimum conditions were used for the determination of formaldehyde in real finger-paints by means of the previous addition of known quantities of this analyte to the paint. Results were compared with those obtained with supercritical fluid extraction and subsequent chemical derivatization and an improvement of sensitivity as well as a reduction of time of analysis, solvent waste and reagents consumption were observed.

A QTL on pig chromosome 4 affects fatty acid metabolism: evidence from an Iberian by Landrace intercross

Three Iberian boars were bred to 31 Landrace sows to produce 79 F1 pigs. Six F1 boars were mated to 73 F1 sows. The F2 progeny from 33 full-sib families (250 individuals) were genotyped for seven microsatellites spanning the length of chromosome 4. Least squares procedures for interval mapping were used to detect quantitative trait loci (QTL). A permutation test was used to establish nominal significance levels associated with QTL effects, and resulting probability levels were corrected to a genomewide basis. Observed QTL effects were (genomewide significance, position of maximum significance in centimorgans): percentage of linoleic acid in subcutaneous adipose tissue (< 0.01, 81); backfat thickness (< 0.01, 83); backfat weight (< 0.01, 80); longissimus muscle area (0.02, 83); live weight (0.19, 88); and percentage of oleic acid in subcutaneous adipose tissue (0.25, 81). Gene action was primarily additive. The Iberian genotypes were fatter, slower growing, and had lower linoleic and higher oleic acid contents than Landrace genotypes. The interval from 80 to 83 cM contains the FAT1 and A-FABP loci that have been shown previously to affect fat deposition in pigs. This is the first report of a QTL affecting fatty acid composition of subcutaneous adipose tissue in pigs and provides a guide for the metabolic pathways affected by candidate genes described in this region of chromosome 4.

Epidermal growth factor impairs the cytochrome C/caspase-3 apoptotic pathway induced by transforming growth factor beta in rat fetal hepatocytes via a phosphoinositide 3-kinase-dependent pathway

Transforming growth factor beta (TGF-beta)-mediated apoptosis is one of the major death processes in the liver. We have previously shown that epidermal growth factor (EGF) is an important survival signal for TGF-beta-induced apoptosis in fetal hepatocytes (Fabregat et al., FEBS Lett 1996;384:14-18). In this work we have studied the intracellular signaling implicated in the protective effect of EGF. We show here that EGF activates p42 and p44 mitogen-activated protein kinases (MAPK). However, mitogen extracellular kinase (MEK) inhibitors do not block the survival effect of EGF. EGF also activates phosphoinositide 3-kinase (PI 3-kinase) and protein kinase B (PKB/AKT) in these cells. The presence of PI 3-kinase inhibitors blocks the protective effect of EGF on cell viability, DNA fragmentation, and caspase-3 activity. We have found that TGF-beta disrupts the mitochondrial transmembrane potential (DeltaPsi(m))( )and activates the release of cytochrome c, this effect being blocked by EGF, via a PI 3-kinase-dependent pathway. A detailed study on bcl-2 superfamily gene expression shows that TGF-beta produces a decrease in the messenger RNA (mRNA) and protein levels of bcl-x(L), an antiapoptotic member of this family, capable of preventing cytochrome c release. EGF is able to maintain bcl-x(L) levels even in the presence of TGF-beta. PI 3-kinase inhibitors completely block the protective effect of EGF on TGF-beta-induced bcl-x(L )down-regulation. We conclude that PI 3-kinase mediates the survival effect of EGF on TGF-beta-induced death by acting upstream from the mitochondrial changes, i.e., preventing bcl-x(L) down-regulation, cytochrome c release, and activation of caspase-3.

[Immediate results in percutaneous mitral valvuloplasty with the Nucleus balloon]

We present the immediate results of mitral valvuloplasty in 10 patients using Nucleus balloon. Several publications show highly successful results obtained with the Inoue balloon and double balloon technique. There are no publications of Nucleus balloon. We consider that this device could offer several advantages according to its physical and technical characteristics. We performed the procedure in 10 female patients, with severe mitral valve stenosis, with an average age of 44.8 years (23-70) and an average Wilkins score of 7.5 (6-9), using a combined technique. The increase in mitral valve area with Gorlin equation was 1.03 +/- .13 to 2.6 +/- .67 cm2, the decrease in transmitral gradient from 15 +/- 4.1 to 3.42 +/- 2.6 mm Hg, and decrease in systolic pulmonary pressure from 54.1 +/- 18.8 to 24.9 +/- 5.1 mm Hg. One patient developed grade I mitral insufficiency after the procedure, and another non significant interatrial shunt.

CONCLUSIONS

Good results are obtained with this balloon, the valvuloplasty technique is more simple than with double balloon, it is much cheaper than Inoue balloon and we consider it could be useful in moderately calcified valves.

Detection of the fragile X syndrome protein for the evaluation of FMR1 intermediate alleles

Molecular screening programs in mentally retarded individuals have been performed in several populations worldwide. One finding has been an excess of FMR1 intermediate alleles in a population with learning difficulties. However, other published reports with similar characteristics did not corroborate those previous results. In order to contribute additional data from our population, we studied 563 patients affected with nonspecific mental retardation (MRX) that did not present a CGG expansion in the FMR1 gene and 208 individuals as a control population. Forty MRX patients presented alleles within the intermediate range. Among them, one case showed a pattern of expression of the FMR1 protein (FMRP) concordant with a fragile X syndrome case with an intermediate allele/full mutation mosaicism, although it was not detected by Southern blot analysis. Statistical analysis was performed again showing no statistically significant difference regarding the intermediate allele frequency in the MRX and control populations. This finding is in agreement with the hypothesis that the incidence of intermediate FMR1 alleles in MRX populations does not seem to be higher than in control populations, and it emphasizes the importance of FMRP detection as a diagnostic tool for fragile X syndrome.

Highly enantioselective esterification of racemic ibuprofen in a packed bed reactor using immobilised Rhizomucor miehei lipase

A systematic study of the enantioselective resolution of ibuprofen by commercial Rhizomucor miehei lipase (Lipozyme(R) IM20) has been carried out using isooctane as solvent and butanol as esterificating agent. The main variables controlling the process (temperature, ibuprofen concentration, ratio butanol:ibuprofen) have been studied using an orthogonal full factorial experimental design, in which the selected objective function was enantioselectivity. This strategy has resulted in a polynomial function that describes the process. By optimizing this function, optimal conditions for carrying out the esterification of racemic ibuprofen have been determined. Under these conditions, enantiomeric excess and total conversion values were 93.8% and 49.9%, respectively, and the enantioselectivity was 113 after 112 h of reaction. These conditions have been considered in the design of a continuous reactor to scale up the process. The esterification of ibuprofen was properly described by pseudo first-order kinetics. Thus, a packed bed reactor operating as a plug-flow reactor (PFR) is the most appropriate in terms of minimizing the residence time compared with a continuous stirred tank reactor (CSTR) to achieve the same final conversion. This reactor shows a similar behavior in terms of enantioselectivity, enantiomeric excess, and conversion when compared with batch reactors. A residence-time distribution (RTD) shows that the flow model is essentially a plug flow with a slight nonsymmetrical axial dispersion (Peclet number = 43), which was also corroborated by the model of CSTR in series. The stability of the system (up to 100 h) and the possibility of reutilization of the enzyme (up to four times) lead to consider this reactor as a suitable configuration for scale up of the process.

Comparative in vitro activities of linezolid, quinupristin-dalfopristin, moxifloxacin, and trovafloxacin against erythromycin-susceptible and -resistant streptococci

The in vitro activities of the new agents linezolid, quinupristin-dalfopristin, moxifloxacin, and trovafloxacin were determined and compared with those of penicillin, clindamycin, and four macrolides against 53 erythromycin-resistant Streptococcus pneumoniae, 117 S. pyogenes (64 erythromycin-susceptible and 53 -resistant), and 101 S. agalactiae (53 erythromycin-susceptible and 48 -resistant) isolates. Differentiation of macrolide resistance phenotypes was performed by the double-disk method. The genetic basis for macrolide resistance in 52 strains was also determined. The M phenotype was found in 84.9, 6.3, and 1.9% of S. pyogenes, S. agalactiae, and S. pneumoniae isolates, respectively. These strains were susceptible to miocamycin and clindamycin. Strains with the inducible phenotype accounted for 27.1% of S. agalactiae isolates and 9.4% each of S. pyogenes and S. pneumoniae isolates. All erythromycin-resistant isolates were also resistant to the 14- and 15-membered macrolides tested. Strains with all three phenotypes were susceptible to </=2 microgram of linezolid per ml. Quinupristin-dalfopristin exhibited good in vitro activity against all strains, irrespective of their resistance to erythromycin (MICs at which 90% of the isolates tested were inhibited [MIC(90)s], 0.2 to 1 microgram/ml). Against the erythromycin-resistant S. pyogenes and S. agalactiae strains, moxifloxacin and trovafloxacin were the most active agents (MIC(90)s, 0.1 microgram/ml). The new antimicrobials evaluated may be alternative agents to treat infections caused by macrolide-resistant as well as macrolide-susceptible streptococci.

The SRY gene HMG-box in micro- and megabats

Sex determination in mammals is controlled by the Y-linked SRY gene, which encodes a transcription factor with a DNA-binding motif of the HMG type. The only conserved region in this gene is the HMG-box, whose nucleotide sequence is currently available in a number of mammalian taxa. However, nothing is known about this gene in bats. Here, we report partial sequences of the SRY HMG-box from four microbat and four megabat species. We used the SRY HMG- box sequences from micro- and megabats to test the phylogenetic relationships between microbats, megabats, and primates. In maximum parsimony and maximum-likelihood trees, mega- and microbat branches start in the same internal node, which is consistent with a monophyletic origin of this mammalian group.

Variability of invariant mouse CD3epsilon chains detected by anti-CD3 antibodies

Current models of the TCR / CD3 complex assume that, in mature peripheral T lymphocytes, variability is restricted to the alpha beta (or gamma delta) chains of the TCR heterodimer responsible for antigen recognition, whereas the CD3 polypeptides involved in signal transmission are invariant. Here we show that mouse CD4(+) T lymphocytes and T cell lines are bound with different avidity by anti-CD3 monoclonal antibodies. These findings cannot be accounted for by allelic differences between CD3 chains, by the nature of the TCR chains, or by the ratio of CD3epsilon delta to CD3epsilon gamma chain pairing. Rather, they are linked to heterogeneity of the N-terminal region of CD3epsilon chains, as detected by peptide-specific antibodies. In turn, these differences among CD3epsilon chains correlate with variations in the strength of TCR / CD3 interaction. N-terminal CD3epsilon heterogeneity is not due to alternative splicing mechanisms, but rather involves digestion by metalloproteases, as suggested by reverse transcription-PCR amplification and by the effect of protease inhibitors, respectively. Based on these data, we propose a model linking CD3epsilon N-terminal variability with altered CD3 recognition by monoclonal antibodies and TCR / CD3 interaction. This model suggests the possibility of distinct spatial arrangements of the TCR / CD3 complex.

Characterization of genetic polymorphism in the goat beta-lactoglobulin gene

Two new variants have been detected and characterized for the goat beta-lactoglobulin gene at the cDNA level and confirmed at the genomic level. The two polymorphisms are located on exon 7 of the gene. One of the polymorphic sites is produced by a single nucleotide substitution in position +4601, allowing a polymerase chain reaction--restriction fragment length polymorphism (PCR-RFLP) genotyping procedure to be developed using SacII restriction enzyme. The other polymorphic position contains a 10 bp long insertion at position +4641 that can be detected by capillary electrophoresis of the PCR product amplified with a fluorescent primer. The association of these two polymorphisms was also investigated, resulting in the description of two new alleles. Both of these contained the point mutation at the SacII site, with or without the 10 bp insertion at position +4641. The distribution of these new polymorphisms was studied in a population of males of four different goat breeds. The gene frequencies for these variants were similar in Spanish and French breeds.

[Epidemiology of leptospirosis in a livestock production area of the Andes]

A cross-sectional study was conducted to estimate the prevalence of Leptospira infection in populations of workers, cattle, and pigs in livestock operations and to explore some environmental and production system variables associated with seropositivity. The research was done between November 1997 and February 1998 in the municipality of Don Matías, in the northern part of the department of Antioquia, Colombia. The area has a cold climate, and there is a "pigs-grasses-milk" production system that utilizes pig dung to fertilize grazing pastures. A total of 23 farms were studied, and blood samples were obtained from 67 dairy and pig-raising workers, 174 dairy cows, 68 pigs for fattening, and 214 pigs for breeding. The microagglutination test (MAT) was used for six Leptospira serotypes. The seropositivity prevalence was 22.4% among the workers (95% confidence interval: 13.1% to 34.2%), 60.9% among the dairy cows (95% CI: 53.2% to 68.2%), 10.3% in the fattening pigs, and 25.7% in the breeding pigs. Four logistic regression models were constructed to identify the variables that predicted infection in the workers and in the dairy cows. A high prevalence of infection with Leptospira (serotypes pomona, bratislava, and hardjo) was found in this production system, where conditions are favorable for transmitting this microorganism to the different animal species and to humans.

Rare variants in the promoter of the fragile X syndrome gene (FMR1)

Fragile X syndrome, the most common form of familial mental retardation, is mainly caused by the expansion of an unstable region of CGG repeats in the 5' untranslated region of the FMR1 (Fragile X Mental Retardation-1) gene. Molecular tools to detect an abnormal CGG expansion in FMR1 include Southern blot hybridization and PCR amplification. Southern blotting with the StB12.3 probe and Eco RI/Eag I double digestion is widely used as a routine test for fragile X syndrome diagnosis in laboratories around the world. A patient with mental retardation of unknown origin showed absence of digestion for Eag I due to a -149C-->G substitution in the CpG island of the FMR1 gene, which destroys that restriction enzyme site. Screening for other changes around that region also detected a -154insGGC in a patient with a phenotype highly suggestive of fragile X syndrome but without CGG expansion. Expression studies did not show any abnormal changes in FMR1 function. In summary, we have identified two different changes (a C to G substitution at -149 and a GGC insertion at -154) in the promoter of the FMR1 gene. These are the first variants described in the promoter of the FMR1 gene.

Photobiological properties of nabumetone (4-[6-methoxy-2-naphthalenyl]-2-butanone), a novel non-steroidal anti-inflammatory and analgesic agent

The photolability of nabumetone (NB, 1, 4-[6-methoxy-2-naphthalenyl]-2-butanone) and its photobiological properties were studied under aerobic and anaerobic conditions using a variety of in vitro phototoxicity assays: photohemolysis, photoperoxidation of linoleic acid, and photosensitized degradation of histidine and thymine. The photodegradation rate of NB in methanol and phosphate buffered saline (PBS) was enhanced under oxygenated media. NB was phototoxic in vitro. The photohemolysis rate was enhanced by deuterium oxide and inhibited by the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO), butylated hydroxyanisole (BHA), sodium azide (NaN3) and reduced gluthathione (GSH). The induced photoperoxidation of linoleic acid was inhibited significantly by sodium azide and reduced gluthathione. Histidine and thymine were photodegraded by a photosensitized reaction induced by NB. A mechanism involving singlet oxygen, radicals and photoproducts is suggested for the observed photoxicity.