A genetic background with low mutational robustness is associated with increased adaptability to a novel host in an RNA virus.

Although mutational robustness is central to many evolutionary processes, its relationship to evolvability remains poorly understood and has been very rarely tested experimentally. Here, we measure the evolvability of Vesicular stomatitis virus in two genetic backgrounds with different levels of mutational robustness. We passaged the viruses into a novel cell type to model a host-jump episode, quantified changes in infectivity and fitness in the new host, evaluated the cost of adaptation in the original host and analyzed the genetic basis of this adaptation. Lineages evolved from the less robust genetic background demonstrated increased adaptability, paid similar costs of adaptation to the new host and fixed approximately the same number of mutations as their more robust counterparts. Theory predicts that robustness can promote evolvability only in systems where large sets of genotypes are connected by effectively neutral mutations. We argue that this condition might not be fulfilled generally in RNA viruses.

Doxorubicin and cyclophosphamide followed by weekly docetaxel as neoadjuvant treatment of early breast cancer: analysis of biological markers in a GEICAM phase II study.

INTRODUCTION: To evaluate the sequential administration of doxorubicin (A) and cyclophosphamide (C) followed by weekly docetaxel in women with stage II to IIIA breast cancer. PATIENTS AND METHODS: Patients received 60 mg/m(2) of A and 600 mg/m(2) of C every three weeks for four cycles followed by 12 infusions of weekly docetaxel at a dose of 36 mg/m(2) and with a 2-week resting period. RESULTS: Sixty-three women were included. On an intention-to- treat basis, clinical response rate was 90% (95% CI: 83-98), with 46% complete responses. Breast-conserving surgery could be performed in 43 patients (68%). Complete pathological responses in the breast were confirmed in 17% of patients. No correlations between levels of expression of topoisomerase II alpha, survivin or p27 and the pathological response were detected. The study treatment was generally well tolerated. CONCLUSION: Neoadjuvant AC followed by weekly docetaxel is a feasible regimen for patients with early-stage breast cancer.

Doxorubicin and cyclophosphamide followed by weekly docetaxel as neoadjuvant treatment of early breast cancer: analysis of biological markers in a GEICAM phase II study

INTRODUCTION: To evaluate the sequential administration of doxorubicin (A) and cyclophosphamide (C) followed by weekly docetaxel in women with stage II to IIIA breast cancer. PATIENTS AND METHODS: Patients received 60 mg/m(2) of A and 600 mg/m(2) of C every three weeks for four cycles followed by 12 infusions of weekly docetaxel at a dose of 36 mg/m(2) and with a 2-week resting period. RESULTS: Sixty-three women were included. On an intention-to- treat basis, clinical response rate was 90% (95% CI: 83-98), with 46% complete responses. Breast-conserving surgery could be performed in 43 patients (68%). Complete pathological responses in the breast were confirmed in 17% of patients. No correlations between levels of expression of topoisomerase II alpha, survivin or p27 and the pathological response were detected. The study treatment was generally well tolerated. CONCLUSION: Neoadjuvant AC followed by weekly docetaxel is a feasible regimen for patients with early-stage breast cancer (AU)

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Refined analysis of genetic variability parameters in hepatitis C virus and the ability to predict antiviral treatment response.

Hepatitis C virus (HCV) infects approximately 3% of the world population. The chronicity of hepatitis C seems to depend on the level of genetic variability. We have recently (Torres-Puente et al., J Viral Hepat, 2008; 15: 188) reported genetic variability estimates from a large-scale sequence analysis of 67 patients infected with HCV subtypes 1a (23 patients) and 1b (44 patients) and related them to response, or lack of, to alpha-interferon plus ribavirin treatment.. Two HCV genome regions were analysed in samples prior to antiviral therapy, one compressing the three hypervariable regions of the E2 glycoprotein and another one including the interferon sensitive determining region and the V3 domain of the NS5A protein. Haplotype and nucleotide diversity measures showed a clear tendency to higher genetic variability levels in nonresponder than in responder patients. Here, we have refined the analysis of genetic variability (haplotype and nucleotide diversity, number of haplotypes and mutations) by considering their distribution in each of the biologically meaningful subregions mentioned above, as well as in their surrounding and intervening regions. Variability levels are very heterogeneous among the different subregions, being higher for nonresponder patients. Interestingly, significant differences were detected in the biologically relevant regions, but also in the surrounding regions, suggesting that the level of variability of the whole HCV genome, rather than exclusively that from the hypervariable regions, is the main indicator of the treatment response. Finally, the number of haplotypes and mutations seem to be better discriminators than haplotype and nucleotide diversity, especially in the NS5A region.

Metástasis en colon de un carcinoma lobulillar de mama / No disponible

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Genetic variability in hepatitis C virus and its role in antiviral treatment response.

Hepatitis C virus (HCV) is a major health problem worldwide, infecting an estimated 170 million people. The high genetic variability of HCV contributes to the chronicity of hepatitis C. Here, we report results from a large-scale sequence analysis of 67 patients infected with HCV genotype 1, 23 with subtype 1a and 44 with subtype 1b. Two regions of the HCV genome were analysed in samples prior to combined therapy with alpha interferon plus ribavirin, one compressing the hypervariable regions (HVR1, HVR2 and HVR3) of the E2 glycoprotein and another one including the interferon-sensitive determining region (ISDR) and the V3 domain of the NS5A protein. Genetic diversity measures showed a clear tendency to higher genetic variability levels in nonresponder patients to antiviral treatment than in responder patients, although highly disperse values were present within each response group for both subtypes. A more detailed analysis of amino acid composition revealed the presence of several subtype-specific variants in a few positions, but no discriminating positions between responder and nonresponder patients were detected. Our results also revealed that most amino acid positions were highly conserved, especially for subtype 1a. We conclude that the outcome of the antiviral treatment might depend not only on the nature of one or a few independent positions, but more likely on the combination of several positions along the HCV genome. Moreover, the own host's ability to generate an appropriate systemic response, in combination with the action of antivirals, is also likely to be essential for treatment outcome.

Utilidad de la resonancia magnética en la evaluación local del cáncer de mama: impacto en el cambio de actitud terapéutica en una serie prospectiva de 338 pacientes / No disponible

Introducción: la estadificación del cáncer de mama implicareunir información no sólo sobre el tamaño del tumor principal,sino también sobre la presencia de multifocalidad, multicentricidad,bilateralidad, componente intraductal extenso oextensión al complejo areola-pezón. El objetivo de nuestro estudioes validar la técnica en nuestro entorno asistencial y evaluarel impacto que la RM de mama con contraste ha tenido sobre338 pacientes consecutivas con diagnóstico de cáncer demama en el proceso de la toma de decisión del modelo de tratamiento.Como objetivo secundario se plantea la correlaciónde los hallazgos de la RM con los hallazgos histopatológicos.Material y métodos: estudiamos con RM a 338 pacientesconsecutivas con diagnóstico de cáncer de mama antes de decidircuál era el abordaje terapéutico más adecuado. La intenciónterapéutica se registró antes y después de cada estudio deRM. Se calculó la sensibilidad, la especificidad, el valor predictivopositivo y el valor predictivo negativo de la RM para lesionesadicionales, así como el coeficiente de correlación linealde Pearson para el diámetro del tumor índice o principal.Resultados: en 145 pacientes (42%) se identificaron 164lesiones adicionales, de las cuales 87 (53%) fueron malignas,28 (17%) fueron benignas, 35 (21,3%) se catalogaron comoprobablemente benignas, en 6 (3,6%) no se alcanzó un diagnósticofinal y 8 (4,9%) no quedaron incluidas en la pieza quirúrgicao bien desaparecieron tras la quimioterapia neoadyuvante.Estos hallazgos implicaron un cambio en la actitudterapéutica en 82 pacientes (24,2%). Este cambio se confirmócon los resultados de la anatomía patológica como correcto en69 paciente (20,4%) y como incorrecto o innecesario en 13pacientes (3,8%). El coeficiente de correlación de Pearson resultóser fuertemente positivo (r = 0,784) cuando se compararonlos resultados de la RM y la anatomía patológica...(AU)

Background: breast cancer staging implies gathering informationnot only on the size of the main tumour, but also onmultifocality, multicentricity, bilaterality, presence of an extensiveintraductal component and extension to the nipple-areolarcomplex. The objective of our study is to demonstrate thatbreast magnetic resonance (MR) is the modality of choice inthe staging of breast cancer patients due to the fact that it addsinformation capable of modifying the therapeutic approach inthese patients. A secondary objective is to validate our resultsin our clinical environment.Material and methods: 338 consecutive patients with abreast cancer diagnosis were studied with breast MR beforedeciding the most appropiate therapeutic approach. Therapeuticintention was registered before and after each MRstudy. Sensibility, specificity, postive predictive value (PPV)and negative predictive value (NPV) of MR for additional lesionswas calculated and Pearson's linear correlation coefficientwas calculated for the index lesion diameter.Results: 164 additional lesions were found in 145 patients(42%) of which 87 (53%) were malignant, 28 (17%) were benign,35 (21,3%) were probable benign, 6 (3,6%) had no diagnosisand 8 (4,9%) were not included in the surgical specimenor else dissappeared after neoadjuvant chemotherapy. Thesefindings implied change in therapeutic approach in 82 patients(24,2%). These change was pathologically validated ascorrect in 69 patients (20,4%) and as unnecessary or incorrectin 13 patients (3,8%). Pearson's linear correlation coefficientwas strongly positive (r = 0,784) when MR and pathology resultswere compared. Sensibility, specificity, PPV and NPV ofMR for additional lesions was 90,6, 55,2, 75,7 and 79,5%respectively...(AU)

Evolution of RNA virus in spatially structured heterogeneous environments.

A hallmark of the infectious cycle for many RNA viruses parasitizing multicellular hosts is the need to invade and successfully replicate in tissues that comprise a variety of cell types. Thus, multicellular hosts represent a heterogeneous environment to evolving viral populations. To understand viral adaptation to multicellular hosts, we took a double approach. First, we developed a mathematical model that served to make predictions concerning the dynamics of viral populations evolving in heterogeneous environments. Second, the predictions were tested by evolving vesicular stomatitis virus in vitro on a spatially structured environment formed by three different cell types. In the absence of gene flow, adaptation was tissue-specific, but fitness in all tissues decreased with migration rate. The performance in a given tissue was negatively correlated with its distance to the tissue hosting the population. This correlation decreased with migration rate.

Prevalence of 2314delG mutation in Spanish patients with Usher syndrome type II (USH2).

The Usher syndrome (USH) is a group of autosomal recessive diseases characterized by congenital sensorineural hearing loss and retinitis pigmentosa. Three clinically distinct forms of Usher syndrome have so far been recognized and can be distinguished from one another by assessing auditory and vestibular function. Usher syndrome type II (USH2) patients have congenital moderate-to-severe nonprogressive hearing loss, retinitis pigmentosa, and normal vestibular function. Genetic linkage studies have revealed genetic heterogeneity among the three types of USH, with the majority of USH2 families showing linkage to the USH2A locus in 1q41. The USH2A gene (MIM 276901) has been identified: three mutations, 2314delG, 2913delG, and 4353-54delC, were initially reported in USH2A patients, the most frequent of which is the 2314delG mutation. It has been reported that this mutation can give rise to typical and atypical USH2 phenotypes. USH2 cases represent 62% of all USH cases in the Spanish population, and 95% of these cases have provided evidence of linkage to the USH2A locus. In the present study, the three reported mutations were analyzed in 59 Spanish families with a diagnosis of USH type II. The 2314delG was the only mutation identified in our population: it was detected in 25% of families and 16% of USH2 chromosomes analyzed. This study attempts to estimate the prevalence of this common mutation in a homogeneous Spanish population.

The two faces of mutation: extinction and adaptation in RNA viruses.

From a population standpoint, two main features characterize the replication of RNA viruses and viruses that use RNA as a replicative intermediate: high genetic variability, and enormous fluctuations in population size. Their genetic variability mainly reflects a lack of the proof-reading and post-replicative error correction mechanisms that operate during cellular DNA replication, but recombination and segment exchange can also play an important role. Viral population size can change tremendously as a consequence of transmission between hosts or between different tissues within an infected host. A new infection can be initiated with very few particles that subsequently expand many trillion-fold. Repeated bottleneck events can lead to drastic fitness losses or even to viral extinction, whereas continuously large population sizes result in fitness gains and adaptation. Here we review experimental evidence for the effects of mutation, selection, and genetic drift on the adaptation and extinction of RNA viruses.

Identification of three novel mutations in the MYO7A gene.

Three new mutations in the myosin VIIA gene involved in the pathogenesis of Usher syndrome type Ib are reported. These mutations are K1080X in exon 25, E1170K in exon 28, and Y1719C in exon 37. It is presumed that these mutations are involved in the Usher syndrome Ib phenotype.

Detection of a novel Cys628STOP mutation of the myosin VIIA gene in Usher syndrome type Ib.

A Spanish family with three Usher I syndrome-affected members was linked to markers located on chromosome 11q. A search for mutations on the myosin VIIA gene revealed a novel mutation (Cys628STOP) on exon 16 segregating with the disorder in a homozygous state. This nonsense mutation could be responsible for the disease since it leads to a truncated protein that presumably has no function.

Comparison of the inhibitory potencies of N(G)-methyl-, N(G)-nitro- and N(G)-amino-L-arginine on EDRF function in the rat: evidence for continuous basal EDRF release.

The relative potencies of the argininolytic agents NG-methyl-L-arginine (L-NMA), NG-nitro-L-arginine (L-NNA) and NG-amino-L-arginine (L-NAA) were assayed by their inhibitory effect on both basal and stimulated release of endothelium-derived NO in vitro and in vivo. Basal NO release was indirectly assessed by the ability of the analogs to contract phenylephrine-preconstricted rat aortic rings and their ability to produce a hypertensive response in awake, unanesthetized normotensive rats. In aortic rings, the three analogs induced vasocontraction and inhibited the vasorelaxation mediated by ACh-stimulated endothelial NO release. In this latter assay, L-NNA was 30 times more potent than either L-NMA or L-NAA. In free-moving rats, the agents caused dose-dependent increases in arterial pressure due to the blockade of endogenous NO formation. Dose-response analysis indicated that L-NNA was 87 and 230 times more potent than L-NMA and L-NAA, respectively. Pretreatment with L-NNA was also found to selectively inhibit, but not abolish, the depressor effects of acetylcholine in unanesthetized and phenylephrine- or vasopressin-infused normotensive-pithed rats. These studies indicate that L-NNA is a potent antagonist of endothelium-derived relaxing factor formation in vitro and in vivo. The contractile and hypertensive effects of the argininolytic agents clearly demonstrates that a continuous basal release of endothelium-derived relaxing factor/NO occurs in both isolated vascular rings and whole animals.