Influence of the curvature on the water structure in the headgroup region of phospholipid bilayer studied by the solvent relaxation technique

Solvent relaxation (SR) in 1,2-dioleoyl-palmitoyl-sn-glycero-3-phosphocholine (DOPC) unilamellar vesicles of different size was probed by 6-hexadecanoyl-2-(((2-(trimethylammonium)ethyl)methyl)amino)naphthalene chloride (Patman), 6-propionyl-2-dimethylaminonaphthalene (Prodan) and 4-[(n-dodecylthio)methyl]-7-(N,N-dimethylamino)-coumarin (DTMAC). Patman probes the amount and mobility of the bound water molecules located at the carbonyl region of the bilayer. Membrane curvature significantly accelerates the solvent relaxation process, but does not influence the total Stokes shift, showing that membrane curvature increases the mobility, without affecting the amount of water molecules present in the headgroup region. This pattern was also verified for other phosphatidylcholines. Prodan is located in the phosphate region of the bilayer and probes a more polar, mobile and heterogeneous environment than Patman. The influence of membrane curvature on SR probed by Prodan is similar, however, less pronounced compared to Patman. DTMAC (first time used in SR) shows a broad distribution of locations along the z-axis. A substantial amount of the coumarin chromophores face bulk water. No effect of curvature on SR probed by DTMAC is detectable.     

A potential double role of anti-Lewis X antibodies in Helicobacter pylori-associated gastroduodenal diseases

In this study, we found Lewis X (Le(x)) determinants on 68% of Helicobacter pylori isolates from patients with chronic gastroduodenal diseases. Anti-Le(x) IgG were detected more frequently in the sera from dyspeptic children and adults (45 and 46%), with or without proved (culture) H. pylori infection, than in the sera from healthy individuals (14% and 25%). In contrast, the prevalence of anti-Le(x) IgM was higher in the groups of healthy individuals than in the groups of dyspeptic patients. Moreover, anti-Le(x) monoclonal antibody of IgM class enhanced the uptake of Le(x)(+) but not Le(x)(-) H. pylori isolates by phagocytes. In the sera from some dyspeptic patients, we detected Le(x)-anti-Le(x) IgG immune complexes (Le(x) ICs). There was a great difference between children and adults as regards the presence of Le(x) ICs. The immune complexes were found in the sera from nine out of 29 (27%) H. pylori-infected and three out of eight (37%) uninfected adult dyspeptic patients. In comparison, Le(x)-anti-Le(x) IgG ICs were detected only for two out of 18 (11%) H. pylori-infected children. Le(x) ICs were not found in the sera from healthy individuals. Our results suggest that anti-Le(x) IgM may play a protective role in H. pylori infections. In contrast, anti-Le(x) IgG and particularly Le(x)-anti-Le(x) IgG ICs might contribute to the pathogenesis of chronic H. pylori infections.     

Naturally occurring V1-env region variants mediate simian immunodeficiency virus SIVmac escape from high-titer neutralizing antibodies induced by a protective subunit vaccine

Macaques which developed high-titer neutralizing antibodies (htNAb) after immunization with a virion-derived oligomeric envelope glycoprotein subunit vaccine were protected against a homologous simian immunodeficiency virus SIVmac challenge. Here we demonstrate that the htNAb could be overcome by V1-env region variants isolated ex vivo from an SIVmac-infected macaque. The results further suggest that the development of V1-env region neutralization escape mutants is also necessary for survival of the virus in infected macaques. The immunological capacity of a single variable region to induce neutralizing antibodies in vaccinated and infected macaques initiate new ideas for a successful vaccine strategy.     

Molecular diagnosis of and carrier screening for the neuronal ceroid lipofuscinoses

The neuronal ceroid lipofuscinoses (NCLs) are a large group of autosomal recessive lysosomal storage disorders with both enzymatic deficiency and structural protein dysfunction. Three typical forms, the infantile (INCL), late-infantile (LINCL), and juvenile (JNCL), are among the most common childhood-onset neurodegenerative disorders. They result from mutations on genes CLN1, CLN2, and CLN3, respectively. We determined that the mutations 223A --> G and 451C --> T in CLN1, T523-1G --> C, and 636 C --> T in CLN2, and deletion of a 1.02-kb genomic fragment in CLN3 are the five common mutations for NCL. To offer clinical genetic testing for the NCLs, we have developed simple and quick PCR-based molecular tests for detecting INCL-, LINCL-, and JNCL-affected individuals from 180 NCL families (27 INCL, 76 LINCL, and 77 JNCL). The sensitivity of testing to detect NCL patients among clinically suspected individuals was determined to be 78% (21/27) for INCL, 66% (54/76) for LINCL, and 75% (58/77) for JNCL. When molecular screening for carriers was conducted among the normal siblings or parents of the probands, we identified two carriers out of three individuals tested for INCL, 20/56 (35.7%) carriers for LINCL, and 48/106 (45.3%) carriers for JNCL families. In addition, 5% (9/180) of NCL patients revealed genetic heterogeneity and were reclassified. Seven patients previously diagnosed as having JNCL were now found to carry mutations of CLN2 (5/7) or CLN1 (2/7) and 2 with late-infantile onsets were identified as carrying mutations of CLN1. Our data demonstrate the importance of DNA testing to detect accurately both affected individuals and carriers in NCL families.     

Hypothesis of a proton switch in QM/MM modelling of interaction of dUMP analogues with thymidylate synthase

Quantum mechanical, molecular mechanics and molecular dynamics (MD) methods were used to investigate initial steps of 2′-deoxyuridine-5′-monophosphate (dUMP) methylation catalysed by the thymidylate synthase (TS) enzyme. The amino acid residues surrounding the active site within a 10 Å radius sphere were modelled with the combined quantum mechanical (B3LYP/LANL2DZ) and molecular mechanics ONIOM double-layer method. The results indicated the initial nucleophilic attack of Cys146 on dUMP to be concerted with formation of a hydrogen bond to the oxygen O4 of dUMP. Moreover, the proton in the vicinity of the O4 atom appears to act as a ‘proton switch’: if a proton is present near O4, it stabilises the S(Cys146)–C6(dUMP) sulphur–carbon bond, but if it is absent, the sulphur–carbon bond does not form. If the O4 oxygen is replaced by sulphur atom, the ‘switch effect’ does not occur. The suggested correlation between the strength of hydrogen bond involving O4 oxygen and the ability of dUMP to form bonds at C6 corresponds well to the crystal structures of TS complexes available in the Protein Data Bank. In the vast majority of crystal structures, the presence of the S(Cys146)–C6(dUMP) bond was coupled with the presence of hydrogen bond between the dUMP O4 atom and the conserved Asn177. The ‘proton switch’ hypothesis is supported also by the results of MD studies of TS binary complexes, suggesting that average distance separating S(Cys146) and C6(dUMP) becomes distinctly shorter in the presence of hydrogen bonding between Asn177 and O4.     

Mild Zellweger syndrome due to a novel <Emphasis Type="Italic">PEX6</Emphasis> mutation: correlation between clinical phenotype and in silico prediction of variant pathogenicity

Zellweger syndrome (ZS) is a consequence of a peroxisome biogenesis disorder (PBD) caused by the presence of a pathogenic mutation in one of the 13 genes from the PEX family. ZS is a severe multisystem condition characterized by neonatal appearance of symptoms and a shorter life. Here, we report a case of ZS with a mild phenotype, due to a novel PEX6 gene mutation. The patient presented subtle craniofacial dysmorphic features and slightly slower psychomotor development. At the age of 2 years, he was diagnosed with adrenal insufficiency, hypoacusis, and general deterioration. Magnetic resonance imaging showed a symmetrical hyperintense signal in the frontal and parietal white matter. Biochemical tests showed elevated liver transaminases, elevated serum very long chain fatty acids, and phytanic acid. After the death of the child at the age of 6 years, molecular diagnostics were continued in order to provide genetic counseling for his parents. Next generation sequencing (NGS) analysis with the TruSight One? Sequencing Panel revealed a novel homozygous PEX6 p.Ala94Pro mutation. In silico prediction of variant severity suggested its possible benign effect. To conclude, in the milder phenotypes, adrenal insufficiency, hypoacusis, and leukodystrophy together seem to be pathognomonic for ZS.     

Stimulation of healing of chronic wounds by epidermal growth factor.

We evaluated the effect of topical epidermal growth factor treatment on healing of chronic wounds in a prospective, open-label, crossover trial. Five males and four females who ranged in age from 40 to 72 years (average 57 +/- 9 years) were enrolled. Four patients had adult-onset diabetes mellitus, two had rheumatoid arthritis, two had old burn scars, and one had a failed abdominal incision. The average duration of the ulcers prior to treatment with epidermal growth factor was 12 +/- 5 months (range 1 to 48 months). Following failure of the wounds to heal with conventional therapies, including debridement, skin graphs, and vascular reconstruction, wounds were treated twice daily with Silvadene alone for periods ranging from 3 weeks to 6 months. No evidence of healing was observed in any of the patients' wounds during Silvadene treatment, and patients were crossed over to twice a day treatment with Silvadene containing 10 micrograms epidermal growth factor per gram. Wounds of eight patients healed completely with epidermal growth factor-Silvadene treatment in an average of 34 +/- 26 days (mean +/- SD, range 12 to 92 days) and did not reoccur for periods ranging from 1 to 4 years. One patient failed therapy. These results suggest that topical treatment of chronic wounds with epidermal growth factor may stimulate healing.     

Influence of castration of the neonatal rat on the contractile effects of barium chloride and adrenaline in isolated vas deferens: the role of calcium

Time-response curves to maximal concentrations of barium chloride (BaCl2) (3 X 10(-2) M) and adrenaline (10(-4) M) were studied in vasa deferentia from 3-month-old rats castrated at birth. Either barium or adrenaline was left in the organ baths for 5-min periods, at intervals of about 30 min, and the corresponding isotonic contractions recorded. Two types of effects were measured: the fade response (Jurkiewicz et al., 1977) and the rate at which responses were reduced after Ca2+ withdrawal from nutrient solution. The fade response for BaCl2 was strikingly greater than that in controls. When calcium was removed from the nutrient solution, an almost complete loss of the response to BaCl2 was achieved in less than 3 min for preparations of 3-day castrates, in about 40 min for the organs of 15-day castrates, and in more than 140 min for normal preparations. Treatment with testosterone, 1 week before the experiments, abolished the fade response to BaCl2 and antagonized the loss of responsiveness observed for this substance in a calcium-deficient solution. These data suggest that the production of testosterone by the testis during the critical period of neonatal differentiation is important for the translocation of calcium ions in the isolated vas deferens of the adult rat.