Choline acetyltransferase expression does not identify early pathogenic events in fetal SMA spinal cord

We investigated the expression of choline acetyltransferase, a specific marker for cholinergic neurons, in control and spinal muscular atrophy fetuses and newborns. By immunoblot we observed at 12 and 15 weeks a similar pattern of choline acetyltransferase expression in spinal muscular atrophy with respect to controls, although at 22 weeks this expression was reduced, probably due to a smaller number of motor neurons in the spinal muscular atrophy spinal cord. By immunohistochemistry, the counting of positive and negative motor neurons for choline acetyltransferase immunostaining in control and spinal muscular atrophy fetuses showed a similar proportion at all stages analyzed. The choline acetyltransferase-negative motor neurons were of similar appearance in both groups. After birth, chromatolytic motor neurons were detected in spinal muscular atrophy, all of which were choline acetyltransferase-negative. Our results in spinal muscular atrophy fetuses indicate that choline acetyltransferase immunostaining does not identify early events in neuronal pathogenesis and suggest that the spinal muscular atrophy surviving motor neurons may not be dysfunctional during this period. Furthermore, spinal muscular atrophy choline acetyltransferase-negative motor neurons showed detectable pathological changes only after birth, indicating that choline acetyltransferase is a late marker for motor neuron degeneration and not a primary contributing factor in this process.     

Partial D-amino acid substitution: Improved enzymatic stability and preserved Ab recognition of a MUC2 epitope peptide

The stability of an immunogen against enzymatic degradation is considered an important factor for the design of synthetic vaccines. For our studies, we have selected an epitope from the tandem-repeat unit of the high-molecular-weight MUC2 mucin glycoprotein, which can be underglycosylated in case of colon cancer. In this study, we prepared a MUC2 peptide containing the PTGTQ epitope of a MUC2 protein backbone-specific mAb 996 and its derivatives. In these peptides, the N- and C-terminal flanking regions were systematically substituted by up to three d-amino acids. Peptides prepared by solid-phase synthesis were tested for their mAb 996 binding in competitive ELISA experiments, and their stability was studied in serum and lysosomal preparation. Our data show that the epitope function of peptide (15)TPTPTGTQTPT(25) is retained even in the presence of two d-amino acid residues at its N-terminal flanking region and up to three at its C-terminal flanking region (tpTPTGTQtpt). Also, this partly d peptide shows high resistance against proteolytic degradation in diluted human serum and in lysosomal preparation. These findings suggest that, by appropriate combination of structural modifications (namely, d-amino acid substitution) in the flanks of an Ab epitope, it is feasible to construct a synthetic antigen with preserved recognition properties and high stability against enzymatic degradation. Peptides tPTPTGTQTpt and tpTPTGTQTpt derived from this study can be used for immunization experiments and as potential components of synthetic vaccines for tumor therapy.     

The coat protein of Rabbit hemorrhagic disease virus contains a molecular switch at the N-terminal region facing the inner surface of the capsid

To function adequately, many if not all proteins involved in macromolecular assemblies show conformational polymorphism as an intrinsic feature. This general strategy has been described for many essential cellular processes. Here we describe this structural polymorphism in a viral protein, the coat protein of Rabbit hemorrhagic disease virus (RHDV), which is required during virus capsid assembly. By combining genetic, structure modeling, and cryo-electron microscopy and image processing analysis, we have established the mechanism that allows RHDV coat protein to switch among quasi-equivalent conformational states to achieve the appropriate curvature for the formation of a closed shell. The RHDV capsid structure is based on a T = 3 lattice, containing 180 copies of identical subunits, similar to those of other caliciviruses. The quasi-equivalent interactions between the coat proteins are achieved by the N-terminal region of a subset of subunits, which faces the inner surface of the capsid shell. Mutant coat protein lacking this N-terminal sequence assembles into T = 1 capsids. Our results suggest that the polymorphism of the RHDV T = 3 capsid might bear resemblance to that of plant virus T = 3 capsids.     

Protein kinase A increases electrical stimulation-induced neuronal nitric oxide release in rat mesenteric artery

The aim of this study was to analyse the possible influence of cyclic AMP-protein kinase A (cAMP-PKA) activation on neuronal nitric oxide (NO) release induced by electrical field stimulation in mesenteric arteries from Wistar Kyoto (WKY) rats. Western blot experiments demonstrated the expression of neuronal NO synthase (nNOS) in mesenteric artery from WKY rats; however, electrical field stimulation alone did not induce detectable NO release. Preincubation with forskolin allowed NO release induced by electrical field stimulation, which was abolished by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or N(omega)-propil-l-arginine (NPLA), and the PKA inhibitors N-(2-(p-Bromocinnamylamino) ethyl 5-isoquinolinesulfonamide hydrochloride (H-89) or (9R,10S,12S)-2,3,9,10,11, 12-Hexahydro-10-9-methyl-1-oxo-9,12-epoxy-1H-diindolo(1,2,3-fg:3,2,1k)pyrrolo(3,4-l)(1,6) benzodiazocine-10-carboxylic acid hexyl ester (KT-5720). Preincubation with prostacyclin also allowed the NO release induced by electrical field stimulation which was significantly decreased by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or NPLA, and the PKA inhibitors H-89 or KT-5720. The NOS inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) did not modify the vasoconstrictor response induced by electrical field stimulation. However, in the presence of forskolin or prostacyclin, l-NAME increased the vasoconstrictor response to electrical field stimulation. These results indicate that forskolin and prostacyclin allow neuronal NO release induced by electrical field stimulation through a mechanism involving cAMP-PKA activation in rat mesenteric arteries.     

A comparative pharmacokinetic study of micronized estradiol valerate administered alone and in combination with medroxyprogesterone acetate in postmenopausal women

The objective of this study was to evaluate a possible pharmacokinetic interaction between 17beta-estradiol (E2) and medroxyprogesterone (MP) when administered together in a combined tablet because both hormones have common metabolic routes of biotransformation. The study assessed the mean pharmacokinetics parameters of E2 found after 1-dose administration of 2 different tablets containing E2, 1 containing 2 mg of micronized 17beta-estradiol valerate (E2V) and the other, administered after 2 weeks, 2 mg of E2V in combination with 5 mg of medroxyprogesterone acetate (MPA). The subjects were 15 healthy postmenopausal women with normal laboratory and clinic tests. The study was randomized, double blind, crossover, with 2 periods and 2 sequences. The blood samples were obtained at 0, 1, 2, 3, 4, 6, 8, 10, 12, and 24 hours after each administration. The E2 serum concentrations were determined by electrochemoluminiscence assay. From these data, the following pharmacokinetic parameters were calculated for E2 alone and E2 in combination with MPA (E2V/MPA): Cmax = 104.89 +/- 26.96, 103.27 +/- 44.40; AUC0-24 =1900.30 +/- 392.23, 1783.70 +/- 756.39; AUC0-infinity = 5576.06 +/- 4065.87, 5317.89 +/- 3702.54; ka = 1.06 +/- 0.31, 1.09 +/- 0.13; t1/2 = 35.65 +/- 20.62, 36.12 +/- 18.04; MRT = 16.29 +/- 8.77, 16.27 +/- 4.88; V/F = 16.29 +/- 8.76, 16.27 +/- 4.88. No significant differences between the pharmacokinetic parameters of E2 and E2/MPA were found, which led us to conclude that there is no pharmacokinetic interaction.     

Experiences in the invasive treatment of acute coronary syndrome

INTRODUCTION: Primer percutaneous coronary intervention is a very powerful tool in the treatment of acute coronary syndrome. The aim of the authors was to work out and analyse the methods of making the upto-date percutaneous coronary intervention available for patients living far from the Heart Institute. PATIENT AND INTERVENTIONS: Between 1st January 2000 and 31st October 2002, 221 patients with acute coronary syndrome were sent to intensive treatment from Kaposvár to the Heart Institute in Pécs partly by helicopter. The average age of patients was 54 years. 103 of them with acute myocardial infarction and 118 others with unstable angina were catheterised. Revascularization was achieved in 133 cases, and coronary operation in 63 cases. Primary intensive therapy was applied on 34 patients with infarction. RESULTS: No lethal complications arose during transport or operation. Mortality rate coming from cardial complications was only 4% during the first two years. These results are based on well organised cooperation between the Department of Internal Medicine Kaposvár and Heart Institute Pécs. CONCLUSION: Given suitable logistic background and adequate indication the risk of transporting patients can be taken. The percutaneous coronary intervention proved to be successful.