Circadian Rhythm of Cardiac Output, Peripheral Vascular Resistance, and Related Variables by a Beat-to-Beat Monitoring

This study aimed to explore the 24-h patterns of stroke volume, cardiac output, and peripheral vascular resistance along with other correlated variables, such as left ventricular ejection time, ejection velocity index, thoracic fluid index, heart rate, and blood pressure. The study was performed on 12 clinically healthy subjects by means of a noninvasive beat-to-beat monitoring using the thoracic electric bioimpedance technique associated with the automated sphygmomano-metric recording. Time data series were analyzed by means of chronobiological procedures. The results documented the occurrence of a circadian rhythm for all the variables investigated, giving relevance to the beat-to-beat bioperiodicity of cardiac output and peripheral vascular resistance. Temporal quantification of the investigated variables may be useful for a better insight of the chronophysiology of the cardiovascular apparatus.     

Somatic frameshift mutations in the Bloom syndrome BLM gene are frequent in sporadic gastric carcinomas with microsatellite mutator phenotype

Background  

Genomic instability has been reported at microsatellite tracts in few coding sequences. We have shown that the Bloom syndrome BLM gene may be a target of microsatelliteinstability (MSI) in a short poly-adenine repeat located in its coding region. To further characterize the involvement of BLM in tumorigenesis, we have investigated mutations in nine genes containing coding microsatellites in microsatellite mutator phenotype (MMP) positive and negative gastric carcinomas (GCs).     

Influence of galls of Phanacis taraxaci on carbon partitioning within common dandelion, Taraxacum officinale

We examined how leaf galls, induced by the cynipid wasp Phanacis taraxaci, influence the partitioning of photoassimilates within the host, the common dandelion, Taraxacum officinale. Galled and ungalled plants were exposed to ¹⁴CO₂ and the labelled photoassimilates accumulating within galls and other parts of the host were measured. During the growth phase of the gall they were physiological sinks for photoassimilates, accumulating 9% to 70% of total carbon produced by the host, depending upon the number of galls per plant. High levels of ¹⁴C assimilation in the leaves of galled plants compared to controls, suggest that galls actively redirect carbon resources from unattacked leaves of their host plant. This represents a significant drain on the carbon resources of the host, which increases with the number and size of galls per plant. Active assimilation of ¹⁴C by the gall is greatest in the growth phase and is several orders of magnitude lower in the maturation phase. This finding is consistent with physiological and anatomical changes that occur during the two phases of gall development and represents a key developmental strategy by cynipids to ensure adequate food resources before larval growth begins.     

8-[2-(4-Aryl-1-piperazinyl)ethyl]-2H-1,4-benzoxazin-3(4H)-ones: Dual-acting 5-HT1 receptor antagonists and serotonin reuptake inhibitors—Part II

8-[2-(4-Aryl-1-piperazinyl)ethyl]-2H-1,4-benzoxazin-3(4H)-ones have been identified as highly potent 5-HT_1A/B/D receptor antagonists with and without additional SerT activity and a high degree of selectivity over hERG potassium channels. Modulation of the different target activities gave compounds with a range of profiles suitable for further in vivo characterization.     

Functional Complementation in Yeast Allows Molecular Characterization of Missense Argininosuccinate Lyase Mutations

Deficiency of argininosuccinate lyase (ASL) causes argininosuccinic aciduria, an urea cycle defect that may present with a severe neonatal onset form or with a late onset phenotype. To date phenotype-genotype correlations are still not clear because biochemical assays of ASL activity correlate poorly with clinical severity in patients. We employed a yeast-based functional complementation assay to assess the pathogenicity of 12 missense ASL mutations, to establish genotype-phenotype correlations, and to screen for intragenic complementation. Rather than determining ASL enzyme activity directly, we have measured the growth rate in arginine-free medium of a yeast ASL^null strain transformed with individual mutant ASL alleles. Individual haploid strains were also mated to obtain diploid, “compound heterozygous” yeast. We show that the late onset phenotypes arise in patients because they harbor individual alleles retaining high residual enzymatic activity or because of intragenic complementation among different mutated alleles. In these cases complementation occurs because in the hybrid tetrameric enzyme at least one active site without mutations can be formed or because the differently mutated alleles can stabilize each other, resulting in partial recovery of enzymatic activity. Functional complementation in yeast is simple and reproducible and allows the analysis of large numbers of mutant alleles. Moreover, it can be easily adapted for the analysis of mutations in other genes involved in urea cycle disorders.Argininosuccinic aciduria (ASAuria, MIM 207900)³ is an autosomal recessive disorder of the urea cycle caused by mutations of the ASL gene (hASL, MIM 608310), encoding argininosuccinate lyase (ASL; EC 4.3.2.1.) (1). This enzyme is ubiquitously expressed and catalyzes the reversible breakdown of argininosuccinate to arginine and fumarate. ASL belongs to a superfamily of hydrolases that includes adenylosuccinate lyase and fumarase, which share a homotetrameric structure and a similar catalytic mechanism. The tetrameric structure of ASL accounts for the phenomenon of intragenic complementation. This particular situation occurs when a multimeric protein is formed from subunits produced by differently mutated alleles of the same gene. On complementation, a partially functional hybrid protein is produced from the two distinct types of mutant subunits, neither of which individually has appreciable enzymatic activity (2).ASL participates to the urea cycle, and in humans it is essential for ammonia detoxification, whereas in lower organisms it is required for the biosynthesis of arginine. Saccharomyces cerevisiae strains harboring a deletion of the homolog of human ASL (ARG4) cannot grow on media lacking arginine (3).ASAuria is characterized by accumulation of argininosuccinic acid (ASA) in body fluids, and severe hyperammonaemia. The disease displays clinical heterogeneity with two main clinical phenotypes: the acute/neonatal onset form, with symptoms rapidly progressing to deep coma, apnea, and death (1), and the subacute/late onset type, which is diagnosed in infancy or childhood (4). Such patients may present simply with mental retardation or an epileptic disorder. In both types the diagnosis is established unambiguously by measuring plasma levels of ammonia (not always elevated in the late onset form), ASA, and its anhydrides by plasma amino acids assay (1). Over 40 mutations of the ASL gene have been reported, both amino acid substitutions and truncating variants, which are scattered throughout the gene (5, 6).We have previously reported the identification of novel mutations of the ASL gene in a cohort of Italian patients (7). In this study we employed a yeast model to validate the pathogenicity of missense ASL mutations found in our cohort, to study the effects of different allelic combinations, and to establish possible genotype-phenotype correlations.     

Fatal Chytridiomycosis in the Tyrrhenian Painted Frog

Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosis, is an important factor in the global decline of amphibians. Within Europe, animals that exhibit clinical signs of the disease have only been reported in Spain despite the pathogen’s wide, but patchy, distribution on the continent. Recently, another occurrence of chytridiomycosis was reported in Euproctus platycephalus, the Sardinian brook newt, on the Mediterranean island of Sardinia, but without any evidence of fatal disease. We report further evidence of the emergence of Bd on Sardinia and the first evidence of lethal chytridiomycosis outside of Spain. Unusual mortalities of the Tyrrhenian painted frog (Discoglossus sardus) were found at three sites in the Limbara mountains of northern Sardinia. Molecular and histological screens of corpses, frogs, and tadpoles from these sites revealed infection with Bd. Infection and mortality occurred at locations that are unusual in terms of the published habitat requirements of the pathogen. Given the endemicity, the IUCN Red List status of the amphibian species on Sardinia, and the occurrence of infection and mortality caused by chytridiomycosis, there is serious reason for concern for the impact that disease emergence may have on the conservation of the amphibians of the island.     

Binding of aflatoxins to the 20S proteasome: effects on enzyme functionality and implications for oxidative stress and apoptosis

Aflatoxins (AF) are contaminants of improperly stored foods; they are potent genotoxic and carcinogenic compounds, exerting their effects through damage to DNA. They can also induce mutations that increase oxidative damage. The goal of this study was to evaluate the possibility that a third mechanism could be involved in the carcinogenic action of aflatoxins, namely, direct binding to key enzymes involved in the regulatory pathways of the cell cycle, thereby modulating enzyme functionality. The 20S constitutive and immunoproteasome peptidase and proteolytic activities were assayed in the presence of aflatoxins B1, G1 and M1. All three toxins activated multiple peptidase activities of the proteasome. Aflatoxin (AF) M1 was the most potent activator of proteasome activity, while the constitutive 20S proteasome was specifically stimulated by AFG1. Furthermore, the effects of AFB1 on cultured hepatoma cells were investigated and the various proteasomal activities determined with cell lysates were differently affected. Taking into account the key role of the proteasome in cellular defense against oxidative stress, the carbonyl group content and the activities of antioxidant enzymes in cell lysates were analyzed. The proapoptotic effect of AFB1 was also investigated by measuring caspase-3 activity and cellular levels of p27 and IkappaBalpha.     

CXC chemokine receptor 4 is expressed in uveal malignant melanoma and correlates with the epithelioid-mixed cell type

PURPOSE: Although relatively rare, uveal melanoma is the most common ocular tumor of adults. Up to half of uveal melanoma patients die of metastatic disease. CXCR4, a chemokine receptor, is a prognostic factor in cutaneous melanoma involved in angiogenesis and metastasis formation. The aim of this study was to evaluate the expression of CXCR4 in uveal melanoma. METHODS: CXCR4 was detected by immunohistochemistry in 44 samples of uveal melanoma. Staining was categorized into three semiquantitative classes based on the rate of stained (positive) tumor cells: absence of staining, <50% of cell (+) and >50% (++). Correlations between CXCR4 expression, data on patient and tumor features were studied by contingency tables and the chi2 test. Time-to-event curves were studied using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test. Ninety-five percent confidence intervals (95% CI) of hazard ratios were also reported. RESULTS: Staining for CXCR4 protein was absent in 18 tumors (40.9%), present in <50% of cells in 19 (43.2%) and in >50% of cells in 7 (15.9%) tumors. CXCR4 expression correlated to the epithelioid-mixed cell type (P=0.030). No statistically significant relation emerged between CXCR4 expression, largest tumor diameter (LTD) and extracellular matrix patterns as evaluated through histological patterns stained with periodic acid-Schiff (PAS). Events occurred in 2 out of 18 patients (11.1%) with negative tumors (2 deaths), in 3 out of 19 patients (15.8%) with <50% of positive tumor cells (2 deaths and 1 occurrence of metastases) and in 1 out of 7 patients (14.3%) with >50% of positive tumor cells (1 occurrence of metastases). The cell type (P=0.0457) but not CXCR4 showed prognostic value at univariate analysis. CONCLUSION: This study shows that CXCR4 is commonly expressed in uveal melanoma and correlates with cell type a well-established prognostic factor.