Evidence of a functional CFTR Cl(-) channel in adult alveolar epithelial cells

The cystic fibrosis transmembrane conductance regulator (CFTR) is expressed in the fetal lung, but during lung development it gradually disappears in cells of future alveolar spaces. Recent studies have implicated the CFTR in fluid transport by the adult alveolar epithelium, but its presence has not been demonstrated directly. This study re-evaluated CFTR expression and activity in the adult pulmonary epithelium by using freshly isolated rat alveolar type II (ATII) cells. CFTR mRNA was detected by semiquantitative polymerase chain reaction on the day of cell isolation but was rapidly reduced by 60% after 24 h of cell culture. This was paralleled by a similar decrease of surfactant protein A expression and alkaline phosphatase staining, markers of the ATII cell phenotype. CFTR expression increased significantly on day 4 in cells grown on filters at the air-liquid interface compared with cells submerged or grown on plastic. Significantly higher CFTR expression was detected in distal lung tissue compared with the trachea. The CFTR was also found at the protein level in Western blot experiments employing lysates of freshly isolated alveolar cells. Whole cell patch-clamp experiments revealed cAMP-stimulated, 5-nitro-2-(3-phenylpropylamino)-benzoate-sensitive Cl(-) conductance with a linear current-voltage relationship. In cell-attached membrane patches with 100 microM amiloride in pipette solution, forskolin stimulated channels of approximately 4 pS conductance. Our results indicate that 50-250 of functional CFTR Cl(-) channels occur in adult alveolar cells and could contribute to alveolar liquid homeostasis.     

Synthesis and biological activity of water-soluble maleimide derivatives of the anticancer drug carboplatin designed as albumin-binding prodrugs

Four platinum (II) complexes (13-16) were synthesized by reacting either [Pt trans-DACH](NO(3))(2) with a 6-maleimidocaproic acid, a 15-maleimido-4,7,10,13-tetroxapentadecanoic acid, and a 6-maleimido-4-oxacaproic ester derivative of cyclobutane-1,1-dicarboxylic acid (CDBA) or [Pt(NH(3))(2)](NO(3))(2) with a 6-maleimido-4-oxacaproic ester derivative of CBDA. Both complexes containing the 6-maleimido-4-oxacaproic ester (15, 16) showed good water solubility (>/=8 mg/mL) and CE experiments revealed rapid binding to human serum albumin and the formation of biadducts with dGMP and dAMP. In the MaTu xenograft model in nude mice, both complexes showed an improved antitumor effect at their maximum tolerated dose (2 x 50 mg/kg carboplatin equivalents) compared to therapy with carboplatin at equimolar dose or at its optimal dose (2 x 75 mg/kg).     

The T-stem determines the cytosolic or mitochondrial localization of trypanosomal tRNAsMet

The mitochondrion of Trypanosoma brucei lacks tRNA genes. Organellar translation therefore depends on import of cytosolic, nucleus-encoded tRNAs. Except for the cytosol-specific initiator tRNA(Met), all trypanosomal tRNAs function in both the cytosol and the mitochondrion. The initiator tRNA(Met) is closely related to the imported elongator tRNA(Met). Thus, the distinct localization of the two tRNAs(Met) must be specified by the 26 nucleotides, which differ between the two molecules. Using transgenic T. brucei cell lines and subsequent cell fractionation, we show that the T-stem is both required and sufficient to specify the localization of the tRNAs(Met). Furthermore, it was shown that the tRNA(Met) T-stem localization determinants are also functional in the context of two other tRNAs. In vivo analysis of the modified nucleotides found in the initiator tRNA(Met) indicates that the T-stem localization determinants do not require modified nucleotides. In contrast, import of native tRNAs(Met) into isolated mitochondria suggests that nucleotide modifications might be involved in regulating the extent of import of elongator tRNA(Met).     

Inhaled nebulized nitrite is a hypoxia-sensitive NO-dependent selective pulmonary vasodilator

The blood anion nitrite contributes to hypoxic vasodilation through a heme-based, nitric oxide (NO)-generating reaction with deoxyhemoglobin and potentially other heme proteins. We hypothesized that this biochemical reaction could be harnessed for the treatment of neonatal pulmonary hypertension, an NO-deficient state characterized by pulmonary vasoconstriction, right-to-left shunt pathophysiology and systemic hypoxemia. To test this, we delivered inhaled sodium nitrite by aerosol to newborn lambs with hypoxic and normoxic pulmonary hypertension. Inhaled nitrite elicited a rapid and sustained reduction ( approximately 65%) in hypoxia-induced pulmonary hypertension, with a magnitude approaching that of the effects of 20 p.p.m. NO gas inhalation. This reduction was associated with the immediate appearance of NO in expiratory gas. Pulmonary vasodilation elicited by aerosolized nitrite was deoxyhemoglobin- and pH-dependent and was associated with increased blood levels of iron-nitrosyl-hemoglobin. Notably, from a therapeutic standpoint, short-term delivery of nitrite dissolved in saline through nebulization produced selective, sustained pulmonary vasodilation with no clinically significant increase in blood methemoglobin levels. These data support the concept that nitrite is a vasodilator acting through conversion to NO, a process coupled to hemoglobin deoxygenation and protonation, and evince a new, simple and inexpensive potential therapy for neonatal pulmonary hypertension.     

Age at acquisition of Helicobacter pylori infection: comparison of two areas with contrasting risk of gastric cancer

Background. Helicobacter pylori infection is usually acquired during childhood and is a known risk factor for the development of gastric malignancies in adulthood. It has been reported that early age at first infection may determine a neoplastic outcome in adults. The purpose of this study was to determine the prevalence of Helicobacter pylori infection in children residing in areas with high (Pasto) and low risk (Tumaco) of gastric cancer in Colombia to evaluate whether differences in the age of acquisition of H. pylori infection were present in the two populations. Materials and Methods. The study sample was based on a census taken in 1999. Using the ¹³C‐urea breath test, we compared the prevalence of H. pylori infection among children aged 1–6 years. Results. Among 345 children in Pasto, 206 (59.7%) were H. pylori‐positive, compared with 188 (58.6%) among 321 children in Tumaco. The two populations share a common pattern of very early age at infection and marked increase in prevalence during the first 4 years of life. No differences in any one year were observed when comparing the two groups. Conclusions. The prevalence of infection was similarly high and increased with age in both populations. In these populations the age of acquisition of H. pylori after 1 year of age does not appear to be a primary factor responsible for the differences in the rates of gastric cancer incidence in adults. Previous findings in adults showed lower prevalence of the most virulent genotypes in Tumaco compared to Pasto, and bacterial virulence may play a key role in determining cancer outcome.     

On the physics of the symbol--matter problem in biological systems and the origin of life: affine Hilbert spaces model of the robustness of the internal quantum dynamics of biological systems

In the present paper, some physical considerations of the biological symbol-matter problem is exposed. First of all, the physical concept of quantum dynamical internal measuremental robustness is discussed. In this context, the significance of introducing affine molecular Hilbert spaces, the original (primordeal) internal quantum measurement, and the global constraining nature of time-inversion symmetry restoring, as a special restoration force, is discussed at some length. It is pointed out, as a summary, that global robustness of the internal dynamics of quantum measurements is due to two basic factors: on one hand, the global constraining nature of the chosen specific (symmetry-) restoring force, and on the other, the individual robustness of the discrete local internal measuremental interactions. The second condition is supposed to follow from a system-internalised ("objective") Bohr-type Copenhagen interpretation of quantum mechanics, corresponding, in an external context, to the Generalized Complementarity Principle of Bohr and Elsasser. It is not claimed, however, that this latter problem has been, as yet, satisfactorily settled physically. In fact, if it were, it would amount to a specifically biological quantum theory of internal measurement, which had to be rooted in the original primordeal global internal measurement, amounting to the origin of the genetic code.     

Repair of a minimal DNA double-strand break by NHEJ requires DNA-PKcs and is controlled by the ATM/ATR checkpoint

Mammalian cells primarily rejoin DNA double-strand breaks (DSBs) by the non-homologous end-joining (NHEJ) pathway. The joining of the broken DNA ends appears directly without template and accuracy is ensured by the NHEJ factors that are under ATM/ATR regulated checkpoint control. In the current study we report the engineering of a mono-specific DNA damaging agent. This was used to study the molecular requirements for the repair of the least complex DSB in vivo. Single-chain PvuII restriction enzymes fused to protein delivery sequences transduce cells efficiently and induce blunt end DSBs in vivo. We demonstrate that beside XRCC4/LigaseIV and KU, the DNA-PK catalytic subunit (DNA-PKcs) is also essential for the joining of this low complex DSB in vivo. The appearance of blunt end 3′-hydroxyl and 5′-phosphate DNA DSBs induces a significantly higher frequency of anaphase bridges in cells that do not contain functional DNA-PKcs, suggesting an absolute requirement for DNA-PKcs in the control of chromosomal stability during end joining. Moreover, these minimal blunt end DSBs are sufficient to induce a p53 and ATM/ATR checkpoint function.     

Servers for sequence-structure relationship analysis and prediction

We describe several algorithms and public servers that were developed to analyze and predict various features of protein structures. These servers provide information about the covalent state of cysteine (CYSREDOX), as well as about residues involved in non-covalent cross links that play an important role in the structural stability of proteins (SCIDE and SCPRED). We also discuss methods and servers developed to identify helical transmembrane proteins from large databases and rough genomic data, including two of the most popular transmembrane prediction methods, DAS and HMMTOP. Several biologically interesting applications of these servers are also presented. The servers are available through http://www.enzim.hu/servers.html.     

Genetic demography of Antioquia (Colombia) and the Central Valley of Costa Rica

We report a comparative genetic characterization of two population isolates with parallel demographic histories: the Central Valley of Costa Rica (CVCR) and Antioquia (in northwest Colombia). The analysis of mtDNA, Y-chromosome and autosomal polymorphisms shows that Antioquia and the CVCR are genetically very similar, indicating that closely related parental populations founded these two isolates. In both populations, the male ancestry is predominantly European, whereas the female ancestry is mostly Amerind. In agreement with their isolation, the Amerindian mtDNA diversity of Antioquia and the CVCR is typical of ethnically-defined native populations and is markedly lower than in other Latin American populations. A comparison of linkage disequilibrium (LD) at 18 marker pairs in Antioquia and the CVCR shows that markers in LD in both populations are located at short genetic distances (相似文献   

Maternal aging and chromosomal abnormalities: new data drawn from in vitro unfertilized human oocytes

The effect of maternal age on the incidence of chromosomal abnormalities was investigated on a large sample of 3,042 in vitro unfertilized human oocytes II obtained from 792 women aged 19-46 years and participating in an in vitro fertilization program for various indications. The chromosomal analysis combined a gradual fixation of oocytes and an adapted R-banding technique. A total of 1,397 interpretable karyotypes were obtained. Various types of numerical aberration were observed, involving conventional chromosome nondisjunction (3.5%), single-chromatid nondisjunction (5.9%), complex (0.8%) or extreme aneuploidy (0.5%), diploidy (5.4%), and set of single chromatids (3.8%). No significant difference was found in the mean age of women according to the various types of chromosomal abnormalities. A positive relationship was found between maternal age and the global rate of aneuploidy, in agreement with the findings of epidemiological studies. The incidence of both whole-chromosome nondisjunction and precocious chromatid separation were correlated to maternal aging but the most significant correlation was found between maternal aging and single-chromatid nondisjunction. The rate of diploidy was also correlated to a slight extent to maternal aging, whereas no correlation was found between maternal age and the rate of single-chromatid sets. These data reveal that single-chromatid malsegregation is an essential factor in the age-dependent occurrence of nondisjunction in human oocytes. Disturbance in sister-chromatid cohesion might be a causal mechanism predisposing to premature chromatid separation and subsequently to nondisjunction in female meiosis.